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1
LMCHE010
LABORATORY MANUAL
CHE010
BASIC CHEMISTRY LABORATORY
2
LMCHE010
TABLE OF CONTENTS
S. No. Title of the Experiment Page No.
1 To detect the presence of acid radicals (oxyanions - carbonate, sulphate
and nitrate) in a given salt.
4-8
2 To detect the presence of acid radicals (halides - chloride, bromide and
iodide) in a given salt.
9-13
3 To detect the presence of basic radicals (Gp I, II Pb
+2, Cu
+2).
14-18
4 To detect the presence of basic radicals (Gp III Al
+3, Fe
+2,Cr
+3).
19-23
5 To detect the presence of basic radicals (Gp IV, V Zn
+2,Ni
+2,Ca
+2,Ba
+2).
24-30
6 To detect the presence of basic radicals (Gp VI Mg+2
, K+, NH4
+). 31-35
7 To detect the presence of one cation and one anion from a given mixture.
36-41
8 To determine Electrochemical Chemical Equivalent of Copper using
Copper sulphate solution and Copper electrodes.
42-46
9 To determine the percentage of iron in the given ferrous alloy by
potassium permanganate method.
47-50
10 To prepare phenol formaldehyde resin (bakelite). 51-53
11 To determine carbon monoxide content in emission from petrol vehicle.
54-56
12 To determine dissolved oxygen in a water sample. 57-61
3
LMCHE010
Some rules to be followed in the Lab:
GENERAL RULES:
1. Entry without lab coat in chemistry lab is strictly prohibited.
2. Mobile phones should be switched off and kept in the bag during lab hours.
3. No group discussions are allowed in the lab.
4. Clean the apparatus as well as the slab after your experiment is finished.
5. Do not do any undisciplined activity in lab as you are under strict cc-TV surveillance.
6. Do not use laptop while performing the experiments.
7. Switch off electrical apparatus after their use.
8. Do not throw filter papers in sink, dispose all waste in dustbin.
PRECAUTIONARY RULES:
1. Never pipette out strong acids and base with your mouth, it can be dangerous, therefore use
measuring cylinders for such chemicals.
2. Never try to smell the chemicals as it can be dangerous for you.
3. Cap the bottles after taking chemical as uncovered bottles can be a source of harmful fumes.
4. In case of any accidental spill over of any chemical on you, report your teacher or lab
technician immediately.
5. Report your lab technician if any breakage of glass apparatus takes place.
4
LMCHE010
EXPERIMENT NO. 1
Aim: To detect the presence of acid radicals (oxyanions: carbonate, nitrate and sulphate) in a
given salt.
Equipments to be used: Test tube, test tube holder, Bunsen burner, tripod stand, test tube and watch
glass.
Chemicals required: Inorganic salt, conc. H2SO4, Dil. H2SO4,
Learning objective: (i) Student will be able to understand that anions detected by dil. and conc.
H2SO4 tests can be detected by the evolution of different gases.
(ii) Some of the anions like SO42-
which are not evolved as gases on treatment with by dil. and
conc. H2SO4 tests, can be detected by their independent tests.
Outline of the procedure:
Preparation of Salt solution:
1. Preparation of Water extract (for water soluble salts): Dissolve a small amount of salt in 2-3 mL of
distilled water, filter it and collect the filtrate for various tests.
2. Preparation of Sodium Carbonate extract (for water insoluble salts): Boil a small amount of salt
with 300-400 mg solid sodium carbonate and add 5-6 mL of distilled water, filter and collect the
filtrate for various identification tests.
Test for detection of carbonate
S.No. Experiment Observation Inferance
1 Dilute H2SO4 test: To the small
amount of salt add 1-2 mL of dil.
H2SO4
Colourless, odourless
gas evolved with brisk
effervesnce
CO32-
present
Confirmatory test for Carbonate:
S.No. Experiment Observation Inferance
1 Lime water test: Pass the gas through
lime water
Lime water turns
milky
CO32-
confirmed
2 Pass more of the gas through lime
water
Milkiness disappears CO32-
confirmed
5
LMCHE010
Test for detection of nitrate (NO3-)
S.No. Experiment Observation Inferance
1 Dilute H2SO4 test: To the small amount
of salt add 1-2 mL of dil. H2SO4
No gas evolved CO32-
absent
2 Conc. H2SO4 test: Heat a small amount
of salt with conc. H2SO4
Colourless gas evolved NO3- present
Confirmatory test for Nitrate:
S.No. Experiment Observation Inferance
1 Add copper turnings to the above test
tube
Brown fumes intensify NO3- confirmed
2 Ring test: To water extract, add
freshly prepared ferrous sulphate
and mix thoroughly. Cool the
mixture under the tap. Add 2 mL
conc. H2SO4along the sides of
the test tube without shaking.
A dark brown ring
is formed at the
junction of the two
solutions.
NO3- confirmed
Test for detection of sulphate (SO42-
)
S.No. Experiment Observation Inferance
1 Dilute H2SO4 test: To the small amount
of salt add 1-2 mL of dil. H2SO4
No gas evolved CO32-
absent
2 Concentrated H2SO4 test : Heat a
small amount of salt with conc. H2SO4
No gas evolved NO3- absent
3 BaCl2 test: Take 1 mL water extract of
the salt in water or sodium carbonate
and after acidifying with dilute
hydrochloric acid add BaCl2 solution.
White precipitate
insoluble in conc. HCl
or conc. HNO3 is
obtained.
SO42-
present
4 Lead acetate test: To the water extract
or sodium carbonate extract add glacial
acetic acid and lead acetate solution.
Appearance of white
precipitate
SO42-
confirmed
6
LMCHE010
Required Results: The given salt contains ________________________anion.
Parameters: NA
Relationship: NA
Graphs: NA
Error Analysis: NA
Cautions:
i. Since the experiment deals with acidic and basic conditions. The acids and the bases
should be handled with care and dropper or a measuring cylinder should be used for
addition of it.
ii. Bases like NH4OH and conc. HNO3, HCl, H2SO4 should be used carefully, since they fume
in air the bottle should be corked immediately after its use.
iii. Many solution bumps out while heating; test tube should be kept in a slant position with
its mouth away from the person carrying the experiment to avoid bumping on face.
iv. Concentrated acids should be added along the sides of the testube.
Requirements for Lab Technician:
1. Inorganic salt samples (Salts containing nitrate, sulphate and carbonate)
2. Dil. H2SO4
3. Conc. H2SO4
4. BaCl2 solution
5. Lime water
6. Glacial acetic acid
7. Lead acetate solution
8. Copper turnings
7
LMCHE010
Date of Performance: ________ Worksheet of the student Registration No.______________
Aim: To detect the presence of acid radicals (oxyanions: carbonate, nitrate and sulphate) in a
given salt.
Observation table:
Sample Experiment Observation Inferance
A
B
C
8
LMCHE010
Results and Discussion:
Learning Outcomes (what I have learnt): to be written by the students in 50-70 words.
To be filled in by faculty
S.No Parameter (Scale from 1-10, 1 for
very poor and 10 excellent)
Marks Obtained Maximum
Marks
1 Understanding of the student about the
procedure/apparatus.
20
2 Observations and analysis including
learning outcomes
20
3 Completion* of experiment, Discipline
and Cleanliness
10
Signature of Faculty Total marks Obtained
9
LMCHE010
EXPERIMENT NO. 2
Aim: To detect the presence of acid radicals (halides: chloride, bromide and iodide) in a given
salt.
Equipments to be used: Test tube, test tube holder, Bunsen burner, tripod stand, test tube stand and
watch glass.
Chemicals required: Sample salt, Dil. H2SO4, Conc. H2SO4.
Learning objective: (i) To detect various halogens present in the given salt
(ii) To identify and differentiate them on the basis of Silver nitrate test
Outline of the procedure:
Preparation of Salt solution:
1. Preparation of Water extract (for water soluble salts): Dissolve a small amount of salt in 2-3 mL of
distilled water, filter it and collect the filtrate for various tests.
2. Preparation of Sodium Carbonate extract (for water insoluble salts) : Boil a small amount of salt with
300-400 mg solid sodium carbonate and add 5-6 mL of distilled water, filter and collect the filtrate for
various identification tests.
Test for detection of halides
S.No. Experiment Observation Inferance
1 Dilute H2SO4 test: To the small amount
of salt add 1-2 mL of dil. H2SO4
No gas evolved CO32-
absent
2 Concentrated H2SO4 test: Heat a small
amount of salt with conc. H2SO4
A colourless gas with
pungent smell,which
gives dense white fumes
when a rod dipped in
ammonium hydroxide is
brought near the mouth
of the test tube.
Cl- present
Reddish brown colour
gas with pungent odour
is evolved
Br- present
Violet vapours I- present
10
LMCHE010
Confirmatory test for halides:
S.No. Experiment Observation Inferance
Confirmatory test for chloride
1 MnO2 test: Add a pinch of MnO2 to
above colourless gas
greenish yellow gas
evolves
Cl- confirmed
2 AgNO3(Silver nitrate) test: To
Soda extract/ water extract, add
HNO3 till effervescence stops,
heat and then add AgNO3 solution
curdy white ppt is
obtained which is
soluble in NH4OH
and which disappear on
addition of dil. HNO3.
Cl- confirmed
Confirmatory test for bromide
3 AgNO3(Silver nitrate) test: To
Soda extract/ water extract, add
dil. HNO3 till effervescence stops,
heat and then add AgNO3 solution
yellow ppt is obtained
which is soluble in
NH4OH and which
disappear on addition of
dil. HNO3.
Br- confirmed
4 To Soda extract/ water extract,
add dil HNO3, then 3-4 mL
carbon tetrachloride/ carbon
disulphide and 1 mL of conc.
HNO3. Shake vigorously.
Organic layer turns
orange
Br- confirmed
Confirmatory test for iodide:
5 Take 1 mL of salt solution neutralised
with HCl and add 1 mL chloroform/
carbon tetrachloride/carbon
disulphide. Now add an excess of
chlorine water drop wise and shake
the test tube.
A violet colour appears
in the organic layer
I- confirmed
6 AgNO3 (Silver nitrate) test: Take
1 mL of sodium carbonate
extract acidify it with dil. HNO3
(or take water extract). Add,
silver nitrate solution.
A yellow precipitate
insoluble in NH4OH
solution is obtained.
I- confirmed
11
LMCHE010
Required Results: The given salt contains ______________anion
Parameters: NA
Relationship: NA
Graphs: NA
Error Analysis: NA
Cautions:
1. Since the experiment deals with acidic and basic conditions. The acids and the bases should be
handled with care and dropper or a measuring cylinder should be used for addition of it.
2. Bases like NH4OH and conc. HNO3, HCl, H2SO4 should be used carefully, since they fume in air
the bottle should be corked immediately after its use.
3. Many solution bumps out while heating; test tube should be kept in a slant position with its
mouth away from the person carrying the experiment to avoid bumping on face.
Requirements for Lab Technician:
1. Inorganic salt samples (Salts containing chloride, bromide and iodide)
2. Dil. H2SO4
3. Conc. H2SO4
4. AgNO3 solution
5. Manganese dioxide
6. Dil. HNO3
7. Conc. HNO3
8. Carbon disulphide
12
LMCHE010
Date of Performance: ________ Worksheet of the student Registration No.______________
Aim: To detect the presence of acid radicals (halides: chloride, bromide and iodide) in a given
salt.
Observation table:
Sample Experiment Observation Inference
A
B
C
13
LMCHE010
Results and Discussion:
Learning Outcomes (what I have learnt): to be written by the students in 50-70 words.
To be filled in by faculty
S.No Parameter (Scale from 1-10, 1 for
very poor and 10 excellent)
Marks Obtained Maximum
Marks
1 Understanding of the student about the
procedure/apparatus.
20
2 Observations and analysis including
learning outcomes
20
3 Completion* of experiment, Discipline
and Cleanliness
10
Signature of Faculty Total marks Obtained
14
LMCHE010
EXPERIMENT NO.3
Aim : To detect the presence of basic radicals (Gp I,II Pb+2
,Cu+2
)
Equipments to be used: Test tube, test tube holder, Bunsen burner, tripod stand, test tube
and watch glass.
Chemicals used: Inorganic sample, Dil. HCl, Conc. HCl, H2S.
Learning Objectives: (i) The purpose of the experiment is to make the students
understand how the basic radicals are classified into six groups.
(ii) Student shall come to know that the cations of group I are precipitated as chlorides by
adding dil. HCl.
(iii) Student will also understand that the cations of group II are precipitated only in group
II as their sulphides in the acidic medium on passing H2S.
Outline of the procedure:
Preparation of Original Solution (O.S.): Dissolve 0.1 g of salt in water, dil. HCl
or conc. HCl as per solubility
Analysis of Group I
S.No. Experiment Observation Inferance
1 To aqueous solution of salt, add 5-10
drops of dil. HCl
White ppt Gp I (Pb2+
present)
Wash the residue with water and heat. Centrifuge and collect the filterate and residue.
2. To the filtrate, add 3-5 mL of dil. H2SO4 White ppt Pb
2+ is confirmed.
3. To the filtrate, add 3-5 mL of KI and
ammonium acetate
Yellow ppt Pb
2+ is confirmed.
15
LMCHE010
Analysis of Group II
S.No. Experiment Observation Inferance
1 To Original solution (O.S) add 5-10
drops of dil. HCl
No ppt. Gp I absent
2. Pass H2S to small portion of acidic
solution (dil. HCl). Filter and collect
the residue.
Black ppt. Gp II present
(I) Boil the precipitate of Group II A with dilute nitric acid and add a few drops of alcohol and
dil. H2SO4. Filter the residue
a) White ppt. Pb2+
may be present
Dissolve the precipitate in ammonium
acetate solution. Acidify with glacial
acetic acid and divide the solution into
two parts.
(i) To the first part add potassium
chromate (K2CrO4) solution.
(ii) To the second part, add
potassium iodide solution.
Yellow ppt. of lead
chromate (PbCrO4)
Yellow ppt. of lead
iodide (PbI2)
Pb2+
confirmed
Pb2+
confirmed
(b) If no precipitate is
formed, Pb
2+ absent, Cu
2+
may be present
(i) Add excess of ammonium
hydroxide solution.
(ii) Acidify it with glacial acetic
acid and add potassium
ferrocyanide solution.
Blue solution is formed
Chocolate brown ppt
Cu2+
is confirmed
Cu2+
is confirmed
Required Results: The given salt contains _______________ cation.
Parameters: NA
Relationship: NA
Graphs: NA
16
LMCHE010
Error Analysis: NA
Cautions:
1. Since the experiment deals with acidic and basic conditions. The acids and the bases
should be handled with care and dropper or a measuring cylinder should be used for
addition of it.
2. Bases like NH4OH and conc. HNO3, HCl, H2SO4 should be used carefully, since they fume
in air the bottle should be corked immediately after its use.
3. Many solution bumps out while heating; test tube should be kept in a slant position with
its mouth away from the person carrying the experiment to avoid bumping on face.
Requirements for Lab Technician:
1. Inorganic salt samples (Salts containing Cu2+
and Pb2+
)
2. Dil. HCl
3. Dil. H2SO4
4. H2S gas
5. Potassium iodide
6. Ammonium acetate
7. Potassium chromate
8. Glacial acetic acid
9. Ammonium hydroxide
10. Potassium ferrocyanide
17
LMCHE010
Date of Performance: ________ Worksheet of the student Registration No.______________
Aim: To detect the presence of basic radicals (Gp I, II Pb+2
, Cu+2
)
Observation table:
Sample Experiment Observation Inference
A
B
18
LMCHE010
Results and Discussion:
Learning Outcomes (what I have learnt): to be written by the students in 50-70 words.
To be filled in by faculty
S.No Parameter (Scale from 1-10, 1 for
very poor and 10 excellent)
Marks Obtained Maximum
Marks
1 Understanding of the student about the
procedure/apparatus.
20
2 Observations and analysis including
learning outcomes
20
3 Completion* of experiment, Discipline
and Cleanliness
10
Signature of Faculty Total marks Obtained
19
LMCHE010
EXPERIMENT NO. 4
Aim: To detect the presence of basic radicals (Gp III Al+3
,Fe+2
,Cr+3
)
Equipments to be used: Test tube, test tube holder, Bunsen burner, tripod stand, test tube
and watch glass.
Chemicals used: Inorganic salt, dil. HCl, Conc. HCl, H2S, NH4Cl, NH4OH.
Learning Objectives: (i) Student will be able to understand how Al+3
, Fe+2
, Fe3+
and Cr+3
are precipitated as hydroxides in alkaline medium.
(ii) Student will be able to distinguish between Fe2+
and Fe3+
.
Outline of the procedure:
Preparation of O.S.: Dissolve 0.1 g of salt in water, dil. HCl or conc. HCl as per
solubility
Analysis of Cations:
S.No. Experiment Observation Inferance
1 To Original solution (O.S) add 5-10
drops of dil. HCl No ppt.
Gp I absent
2. Pass H2S to small portion of acidic
solution (dil. HCl). Filter and collect
the residue.
No ppt Gp II absent
3. Add 2-3 drops of conc. HNO3 to O.S.,
which oxidise Fe2+
ions to Fe3+
ions.
Heat the solution for a few minutes.
After cooling add a small amount of
solid ammonium chloride (NH4Cl) and
an excess of ammonium hydroxide
(NH4OH) solution till it smells of
ammonia. Shake the test tube.
Brown or white ppt Gp III present
Collect the residue and add 3-4 mL of water and then add 100 mg sodium peroxide. Separate the residue
and filtrate.
(a) To the above residue add dil. HCl and
divide the solution in 3 parts.
Brown ppt Iron Fe2+
/ Fe3+
present
20
LMCHE010
(i) To part 1, add potassium
ferricyanide K3[Fe(CN)6] solution
(ii) To part 2 add potassium
ferrocyanide K4[Fe(CN)6]
solution
(iii) To part 3 add ammonium
thiocyanate (NH4CNS)
Blue ppt
Dark blue ppt
Blood red ppt
Fe2+
confirmed
Fe3+
confirmed
Fe3+
confirmed
(b) Divide the filtrate in 2 parts. If filtrate is yellow Cr3+
is present
(i) To part 1, add 3-4 mL of
glacial acetic acid and then 3
mL of lead acetate solution
Yellow ppt Cr3+
confirmed
(ii) To part 2 of filtrate, add
NH4Cl and heat White ppt Al3+
present
Dissolve the white precipitate in dilute HCl and divide into two parts.
(i) To the first part add sodium
hydroxide solution and warm. White ppt soluble in
sodium hydroxide Al3+
confirmed
(ii) To the second part first add blue
litmus solution and then ammonium
hydroxide solution drop by drop along
the sides of the test tube.
Blue floating mass in
colourless liquid is
obtained Al
3+ confirmed
Required Results: The given salt contains ___________cation.
Parameters: NA
Relationship: NA
Graphs: NA
Error Analysis: NA
Cautions:
i. Since the experiment deals with acidic and basic conditions. The acids and the
bases should be handled with care and dropper or a measuring cylinder should be
21
LMCHE010
used for addition of it.
ii. Bases like NH4OH and conc. HNO3, HCl, H2SO4 should be used carefully, since they
fume in air the bottle should be corked immediately after its use.
iii. Many solution bumps out while heating; test tube should be kept in a slant position
with its mouth away from the person carrying the experiment to avoid bumping on
face.
Requirements for Lab Technician:
1. Inorganic salt samples (Salts containing Al3+
, Fe2+
, Fe3+
and Cr3+
)
2. Dil. HCl
3. Dil. H2SO4
4. H2S gas
5. Ammonium chloride
6. Ammonium hydroxide
7. Sodium peroxide
8. Potassium ferricyanide
9. Ammonium thiocyanate
10. Potassium ferrocyanide
11. Glacial acetic acid
12. Lead acetate
13. Sodium hydroxide
14. Blue litmus
22
LMCHE010
Date of Performance: ________ Worksheet of the student Registration No.______________
Aim: To detect the presence of basic radicals (Gp III Fe+2
, Fe+3
, Cr+3
, Al3+
)
Observation table:
Sample Experiment Observation Inference
A
B
C
23
LMCHE010
D
Results and Discussion:
Learning Outcomes (what I have learnt): to be written by the students in 50-70 words.
To be filled in by faculty
S.No Parameter (Scale from 1-10, 1 for
very poor and 10 excellent)
Marks Obtained Maximum
Marks
1 Understanding of the student about the
procedure/apparatus.
20
2 Observations and analysis including
learning outcomes
20
3 Completion* of experiment, Discipline
and Cleanliness
10
Signature of Faculty Total marks Obtained
24
LMCHE010
EXPERIMENT NO. 5
Aim: To detect the presence of basic radicals (Gp IV, V Zn+2
, Ni+2
, Ca+2
, Ba+2
)
Equipments to be used: Test tube, test tube holder, Bunsen burner, tripod stand, test tube
and watch glass.
Chemicals used: Inorganic salt, dil. HCl, Conc. HCl, H2S, NH4Cl, NH4OH and
(NH4)2CO3.
Learning Objectives: (i) Student will be able to know that group IV cations i.e. Zn+2
and
Ni+2
are precipitated as sulphides in alkaline medium on passing H2S.
(ii) Student will be able to distinguish between Zn2+
and Ni2+
by various tests.
(iii) Student will be able to know that the cations of group V are precipitated as their
carbonates in alkaline medium by the action of ammonium carbonate.
Outline of the procedure:
Preparation of O.S.: Dissolve 0.1 g of salt in water, dil. HCl or conc. HCl as per
solubility
Analysis for Gp IV cations:
S.No. Experiment Observation Inference
1 To Original solution (O.S) add 5-10
drops of dil. HCl No ppt. Gp I absent
2.
Pass H2S to small portion of acidic
solution (dil. HCl). Filter and collect
the residue.
No ppt Gp II absent
3.
Add 2-3 drops of conc. HNO3 to O.S.,
Heat the solution for a few minutes.
After cooling add a small amount of
solid ammonium chloride (NH4Cl) and
an excess of ammonium hydroxide
(NH4OH) solution till it smells of
ammonia. Shake the test tube.
No ppt Gp III absent
4 Pass H2S to above alkaline solution,
shake and filter Black or white ppt Gp IV present
25
LMCHE010
If White ppt, then Zn2+
may be present. Dissolve the precipitate in dilute HCl by boiling. Divide the
solution into two parts.
(a)
(i) To one part, add sodium hydroxide
solution.
White precipitate
soluble in excess of
sodium hydroxide
solution
Zn2+
confirmed
(ii) Neutralise the second part with
ammonium hydroxide solution and add
potassium ferrocyanide K4[Fe(CN)6]
solution
Bluish ppt Zn2+
confirmed
(b) If black ppt, then Ni2+
may be present
(i) DMG test: Dissolve the precipitate
in aqua regia (3 drops of conc. HNO3
and 6 drops of conc. HCl). Heat
thesolution to dryness and cool.
Dissolve the residue in water. Add
ammonium hydroxide solution till it
becomes alkaline. Add a few drops of
dimethyl glyoxime and shake the test
tube.
Dark red ppt Ni2+
confirmed
Analysis for Gp V cations:
S.No. Experiment Observation Inference
1 To Original solution (O.S) add 5-10
drops of dil. HCl No ppt. Gp I absent
2.
Pass H2S to small portion of acidic
solution (dil. HCl). Filter and collect
the residue.
No ppt Gp II absent
3.
Add 2-3 drops of conc. HNO3 to O.S.,
Heat the solution for a few minutes.
After cooling add a small amount of
solid ammonium chloride (NH4Cl) and
an excess of ammonium hydroxide
(NH4OH) solution till it smells of
ammonia. Shake the test tube.
No ppt Gp III absent
4 Pass H2S to above alkaline solution,
shake and filter No ppt Gp IV absent
26
LMCHE010
5
Take original solution and add a small
amount of solid NH4Cl and an excess
of NH4OH solution followed by solid
ammonium carbonate (NH4)2CO3.
White ppt Gp V present
Preserve a part of ppt for flame test and dissolve rest of the white precipitate by boiling with dilute
glacial acetic acid and divide the solution into two parts
(i) To the first part add potassium
chromate solution.
Yellow ppt Ba
2+ confirmed
(ii) Flame test: Take a platinum wire
and dip it in conc. HCl. Heat it strongly
until the wire does not impart any
colour to the non-luminous flame.Now
dip the wire in the paste of the (Group
V) precipitate in conc. HCl. Heat it in
the flame.
Grassy green flame Ba2+
confirmed
(b) If Ba2+
is absent, then Ca2+
may be present
(i) To another part of the solution, add
ammonium oxalate solution and shake
well.
White ppt Ca2+
confirmed
(ii) Flame test: Take a platinum wire
and dip it in conc. HCl. Heat it strongly
until the wire does not impart any
colour to the non-luminous flame.Now
dip the wire in the paste of the (Group
V) precipitate in conc. HCl. Heat it in
the flame.
Brick red ppt Ca2+
confirmed
Required Results: The given salt contains ___________ cation
Parameters: NA
Relationship: NA
Graphs: NA
Error Analysis: NA
Cautions:
i. Since the experiment deals with acidic and basic conditions. The acids and the
bases should be handled with care and dropper or a measuring cylinder should be
used for addition of it.
ii. Bases like NH4OH and conc. HNO3, HCl, H2SO4 should be used carefully, since they
27
LMCHE010
fume in air the bottle should be corked immediately after its use.
iii. Many solution bumps out while heating; test tube should be kept in a slant position
with its mouth away from the person carrying the experiment to avoid bumping on
face.
Requirements for Lab Technician:
1. Inorganic salt samples (Salts containing Zn2+
, Ni2+
, Ca2+
and Ba2+
)
2. Dil. HCl
3. Dil. H2SO4
4. Dil. HNO3
5. H2S gas
6. Conc. HCl
7. Ammonium chloride
8. Ammonium hydroxide
9. Ammonium carbonate
10. Potassium ferrocyanide
11. Dimethyl glyoxime
12. Potassium chromate
13. Ammonium oxalate
14. Ethanol
28
LMCHE010
Date of Performance: ________ Worksheet of the student Registration No.______________
Aim: To detect the presence of basic radicals (Gp IV, V Zn+2
, Ni+2
, Ca+2
, Ba+2
)
Observation table:
Sample Experiment Observation Inference
A
B
29
LMCHE010
C
D
30
LMCHE010
Results and Discussion:
Learning Outcomes (what I have learnt): to be written by the students in 50-70 words
To be filled in by faculty
S.No Parameter (Scale from 1-10, 1 for
very poor and 10 excellent)
Marks Obtained Maximum
Marks
1 Understanding of the student about the
procedure/apparatus.
20
2 Observations and analysis including
learning outcomes
20
3 Completion* of experiment, Discipline
and Cleanliness
10
Signature of Faculty Total marks Obtained
31
LMCHE010
EXPERIMENT NO. 6
Aim: To detect the presence of basic radicals (Gp VI Mg+2
, K+, NH4
+)
Equipments to be used: Test tube, test tube holder, Bunsen burner, tripod stand,test tube
and watch glass.
Chemicals used: Inorganic salt, dil. HCl, Conc. HCl, H2S, NH4Cl, NH4OH and
(NH4)2CO3.
Learning Objectives: (i) Students will be able to understand that the cations of group VI
i.e. Mg+2
, K+, NH4
+ are neither precipitated as chlorides, sulphides and carbonates.
(ii) Student will be able to detect the presence of independent cations namely Mg+2
, K+,
NH4+.
Outlines of the procedure:
Preparation of O.S.: Dissolve 0.1 g of salt in water, dil. HCl or conc. HCl as per
solubility
Analysis for Gp VI cations:
S.No. Experiment Observation Inference
1 To Original solution (O.S) add 5-10
drops of dil. HCl No ppt. Gp I absent
2.
Pass H2S to small portion of acidic
solution (dil. HCl). Filter and collect
the residue.
No ppt Gp II absent
3.
Add 2-3 drops of conc. HNO3 to O.S.,
Heat the solution for a few minutes.
After cooling add a small amount of
solid ammonium chloride (NH4Cl) and
an excess of ammonium hydroxide
(NH4OH) solution till it smells of
ammonia. Shake the test tube.
No ppt Gp III absent
4 Pass H2S through above alkaline
solution. No ppt Gp IV absent
5
Take original solution and add a small
amount of solid NH4Cl and an excess
of NH4OH solution followed by solid
ammonium carbonate (NH4)2CO3.
No ppt Gp V absent
Gp VI may be present
32
LMCHE010
Confirmatory tests for K+, Mg
2+, NH4
+
S.No Experiment
Observation Inference
1 To O.S., add dil. HCl solution. Add
NH4OH and Na2HPO4 solution. White ppt on scratching Mg
2+ confirmed
2. To O.S., add glacial acetic acid and
sodium cobalt nitrate Yellow ppt K
+ confirmed
3.
Take a platinum wire and dip it in conc.
HCl. Heat it strongly until the wire
does not impart any colour to the non-
luminous flame. Now dip the wire in
the paste of the (Group V) precipitate in
conc. HCl. Heat it in the flame.
Purple flame K+ confirmed
4. To O.S., add Nessler’s reagent
Brown ppt NH4+ confirmed
5. To O.S., add NaOH and heat
Pungent smelling gas is
evolved NH4+ confirmed
Required Results: The given salt contains _____________ cation.
Parameters: NA
Relationship: NA
Graphs: NA
Error Analysis: NA
Cautions:
i. Since the experiment deals with acidic and basic conditions. The acids and the
bases should be handled with care and dropper or a measuring cylinder should be
used for addition of it.
ii. Bases like NH4OH and conc. HNO3, HCl, H2SO4 should be used carefully, since they
fume in air the bottle should be corked immediately after its use.
iii. Many solution bumps out while heating; test tube should be kept in a slant position
with its mouth away from the person carrying the experiment to avoid bumping on
face.
33
LMCHE010
Requirements for Lab Technician:
1. Inorganic salt samples (Salts containing Zn2+
, Ni2+
, Ca2+
and Ba2+
)
2. Dil. HCl
3. Dil. H2SO4
4. Dil. HNO3
5. H2S gas
6. Conc. HCl
7. Ammonium chloride
8. Ammonium hydroxide
9. Ammonium carbonate
10. Sodium hypophosphate
11. Glacial acetic acid
12. Sodium cobalt nitrate
13. Nesseler’s reagent
14. Sodium hydroxide
34
LMCHE010
Date of Performance: ________ Worksheet of the student Registration No.______________
Aim: To detect the presence of basic radicals (Gp VI Mg+2
, K+, NH4
+)
Observation table:
Sample Experiment Observation Inference
A
B
C
35
LMCHE010
Results and Discussion:
Learning Outcomes (what I have learnt): to be written by the students in 50-70 words
To be filled in by faculty
S.No Parameter (Scale from 1-10, 1 for
very poor and 10 excellent)
Marks Obtained Maximum
Marks
1 Understanding of the student about the
procedure/apparatus.
20
2 Observations and analysis including
learning outcomes
20
3 Completion* of experiment, Discipline
and Cleanliness
10
Signature of Faculty Total marks Obtained
36
LMCHE010
EXPERIMENT NO. 7
Aim: To detect the presence of one cation and one anion from a given salt
Equipments to be used: Test tube, test tube holder, Bunsen burner, tripod stand, test tube
and watch glass.
Chemicals used: Inorganic salt, Dil. H2SO4, Conc. H2SO4, dil. HCl, Conc. HCl, H2S,
NH4Cl, NH4OHand (NH4)2CO3.
Learning Objectives: (i) Student will be able to detect cation and anion from any given
salt.
(ii) Student will be able to understand that the cations of group IV are not precipitated in
group II.
Outline of the procedure: As per the detection and confirmatory tests mentioned in
Experiment 1 to Experiment 6, the cation and anion can be detected from a given salt. For
example the salt under analysis is MgSO4, the procedure will be as follows:
Analysis for Anion
Preparation of Water extract (for water soluble salts): Dissolve a small amount of salt
in 2-3 mL of distilled water, filter it and collect the filtrate for various tests.
S.No. Experiment Observation Inferance
1 Dilute H2SO4 test: To the small amount
of salt add 1-2 mL of dil. H2SO4 acid
No gas evolved CO32-
absent
2
Conc. H2SO4 test: Heat a small amount
of salt with conc. H2SO4
No gas evolved Cl-, Br
-, I
- and NO3
-
absent
3 BaCl2 test: Take 1 mL water extract of
the salt in water or sodium carbonate
and after acidifying with dilute
hydrochloric acid add BaCl2 solution.
White precipitate
insoluble in conc. HCl
or conc. HNO3 is
obtained.
SO42-
present
The anion present in the salt is SO42-
37
LMCHE010
Analysis of basic radical
Preparation of Original Solution (O.S.): Dissolve 0.1 g of salt in water or dil. HCl
or conc. HCl as per solubility.
S.No. Experiment Observation Inference
1 To the original solution add 5-10 drops
of dil. HCl No ppt Gp I absent
2. Pass H2S gas throughabove solution. No ppt Gp II absent
3.
Add 2-3 drops of conc. HNO3 to O.S.,
Heat the solution for a few minutes.
After cooling add a small amount of
solid ammonium chloride (NH4Cl) and
an excess of ammonium hydroxide
(NH4OH) solution till it smells of
ammonia. Shake the test tube.
No ppt Gp III absent
4 Pass H2S through above alkaline
solution. No ppt Gp IV absent
5
Take 1-2 mL original solution and add
a small amount of solid NH4Cl and an
excess of NH4OH solution followed by
solid ammonium carbonate (NH4)2CO3.
No ppt (a) Gp V absent
(b) Gp VI may be present
6 To O.S., add dil. HCl solution. Add
NH4OH and Na2HPO4 solution. White ppt on scratching Mg
2+ confirmed
The cation present in the salt is Mg2+
Required Results: The anion ____________ and cation __________________ is present in
the salt.
Parameters: NA
Relationship: NA
Graphs: NA
Error Analysis: NA
Cautions:
1. Since the experiment deals with acidic and basic conditions. The acids and the bases
should be handled with care and dropper or a measuring cylinder should be used for
addition of it.
2. Bases like NH4OH and conc. HNO3, HCl, H2SO4 should be used carefully, since they fume
38
LMCHE010
in air the bottle should be corked immediately after its use.
3. Many solution bumps out while heating; test tube should be kept in a slant position with
its mouth away from the person carrying the experiment to avoid bumping on face.
Requirements for Lab Technician:
1. Inorganic salt samples (Salts containing any cation or anion)
2. Dil. HCl
3. Dil. H2SO4
4. Dil. HNO3
5. H2S gas
6. Conc. HCl
7. Ammonium chloride
8. Ammonium hydroxide
9. Ammonium carbonate
10. Sodium hypophosphate
11. Glacial acetic acid
12. Sodium cobalt nitrate
13. Nesseler’s reagent
14. Sodium hydroxide
39
LMCHE010
Date of Performance: ________ Worksheet of the student Registration No.______________
Aim: To detect the presence of one cation and one anion from a given mixture
Observation table: For Anion:
Sample Experiment Observation Inference
For Cation:
Sample Experiment Observation Inference
40
LMCHE010
41
LMCHE010
Results and Discussion:
Learning Outcomes (what I have learnt): to be written by the students in 50-70 words
To be filled in by faculty
S.No Parameter (Scale from 1-10, 1 for
very poor and 10 excellent)
Marks Obtained Maximum
Marks
1 Understanding of the student about the
procedure/apparatus.
20
2 Observations and analysis including
learning outcomes
20
3 Completion* of experiment, Discipline
and Cleanliness
10
Signature of Faculty Total marks Obtained
42
LMCHE010
EXPERIMENT NO. 8
Aim: To determine Electrochemical Chemical Equivalent of Copper using Copper sulphate
solution and Copper electrodes
Equipments to be used: Copper voltameter, four copper plates, battery of 4 to 5 cells, a rheostat,
one way key, connecting wires, sand paper, weighing balance, ammeter and stop watch
Chemicals used: Copper sulphate, Conc.H2SO4, distilled water, dil HNO3
Learning Objectives:To know about Faraday’s first law of electrolysis: According to
Faraday’s first law of electrolysis, the electrochemical equivalent, Z, is given by the relation:
𝑍 = 𝑤
𝐼 × 𝑡
where w is the mass of metal deposited, I is the current in amperes and t is the time in seconds. If
the value of Z comes out to be fairly constant by passing the same current for different times,
first law of electrolysis is verified.
Procedure:
Clean all the copper plates with nitric acid and wash them thoroughly in running tap
water. Dry one of the plates and clean it with a piece of fine sand paper. Wash it and let it
dry. Weigh accurately.
Dissolve 30 g of powdered copper sulphate in 200 mL water by warming in beaker. Cool
the solution and add Conc. H2SO4 to it. Fill the copper voltameter with this solution.
Arrange the circuit as shown in figure
.
Take out the central plate. Measure its length and breadth dipped in electrolyte. Calculate
the area of plate and double it for total area of both sides dipped in the electrolyte. Put the
plate in electrolyte. A good deposit is obtained when a current of one ampere is passed
for every 100 sq cm of the cathode dipping in electrolyte.
43
LMCHE010
To test the connections, put the plug in key K and adjust the value of the current
approximately equal to the calculated value. See that the current remains constant for
about 5 mins. If on removing the central plate red deposits are seen on it, the connections
are correct.
Replace the central plate by the weighed copper plate, put in the key “K” and start the
stop watch. Note the reading of the ammeter at intervals and see that the current remains
constant. Adjust the current with a rheostat. Stop the stop watch after 30 minutes and at
the same time take out the plug from the key K.
Remove the cathode plate carefully, rinse it immediately in dil. H2SO4 and then wash it
thoroughly in running water. Rinse it with alcohol. Dry it and find its weight accurately.
Repeat the experiment by passing the current for 45 minutes. Note the current in ammeter
after every 15 minutes.
Calculate the electrochemical equivalent for the two observations.
Calculations: Length of the plate dipped = l cm
Breadth of the plate dipped = b cm
Total area dipped, a = 2l x b cm2
Current to be adjusted = a/100 amperes
S.No.
Initial
weight of
cathode
w1(g)
Final
weight of
cathode
w2(g)
Weight of
copper
deposited
w = w2-
w1
Current
I (A)
Time t
(s)
Electrochemical
equivalent
𝑍 = 𝑤
𝐼 × 𝑡
1.
2.
Result: The Electrochemical equivalent of copper is __________ g/C
Scope of the result: As the value of the electrochemical equivalent of copper, Z, comes out to
be fairly constant, it verifies first law of electrolysis.
Parameters: NA
Relationships to be determined: NA
Graphs/Plots: NA
Error Analysis: NA.
44
LMCHE010
Cautions:
i. The cathode plate must be cleaned thoroughly, dried and weighed accurately.
ii. The current should be constant throughout the experiment and should be adjusted at the
rate of one ampere for every 100 sq.cm of the area of the copper plate dipping in copper
sulphate solution.
iii. The plates should not touch each other.
iv. The electrolyte should be fresh and free from impurities.
v. The weighed plate must be connected to the negative pole of battery.
vi. The plate must be rinsed in dilute sulphuric acid as it is removed from the electrolyte,
otherwise the deposit will turn black due to oxidation.
Requirement for Lab Technician:
1. Copper plates
2. Copper sulphate
3. Conc. H2SO4
4. Ethanol
5. Dil. HNO3
45
LMCHE010
Date of Performance: ________ Worksheet of the student Registration No.______________
Aim: To determine Electrochemical Chemical Equivalent of Copper using Copper sulphate
solution and Copper electrodes.
Observations and Calculations: Length of the plate dipped = l cm
Breadth of the plate dipped = b cm
Total area dipped, a = 2l x b cm2
Current to be adjusted = a/100 amperes
S.No.
Initial
weight of
cathode
w1(g)
Final
weight of
cathode
w2(g)
Weight of
copper
deposited
w = w2-
w1
Current
I (A)
Time t
(s)
Electrochemical
equivalent
𝑍 = 𝑤
𝐼 × 𝑡
1.
2.
Results and Discussion:
Error Analysis:
Learning Outcomes (what I have learnt): to be written by the students in 50-70 words.
46
LMCHE010
To be filled in by faculty
S.No Parameter (Scale from 1-10, 1 for
very poor and 10 excellent)
Marks Obtained Maximum
Marks
1 Understanding of the student about the
procedure/apparatus.
20
2 Observations and analysis including
learning outcomes
20
3 Completion* of experiment, Discipline
and Cleanliness
10
Signature of Faculty Total marks Obtained
47
LMCHE010
EXPERIMENT NO. 9
Aim:To determine the percentage of iron in the given ferrous alloy by potassium permanganate
method.
Equipments to be used: Titration flask, pipette, burette, beakers, glass rod, funnel and burette stand
Chemicals used:M/100 KMnO4, sample ferrous alloy solution (20g/L) and Dil. H2SO4.
Learning Objective: (i) To determine the percentage of iron in given alloy :The molarity of the given solution of alloy can be determined by titrating it with standard KMnO4 solution in which
the following redox reaction takes place which is based on the oxidation and the reduction
reaction. The oxidising agent i.e Potassium permanganate oxidises the reducing agent ferrous sulphate and ferrous ammonium sulphate in acidic medium to ferric sulphate.The strength of
alloy can be calculated and hence percentage of iron can be determined.
(ii) To understand the redox reaction in the experiment.
MnO4- + 8H
+ + 5e
- → Mn
2+ + 4H2O (Reduction)
5Fe2+
→ 5Fe3+
+ 5e- (Oxidation)
MnO4- + 8H
+ + 5Fe
2+ → Mn
2+ + 5Fe
3+ + 4H2O (Overall Reaction)
Indicator: KMnO4 acts as self-indicator.
End point: Colorless to faint pink.
Outline of Procedure
Wash the whole apparatus thoroughly with distilled water.
Rinse and fill the burette with the given solution of M/100 KMnO4 solution.
Rinse the pipette with the given ore solution and pipette out 20 mL of the given ore
solution in a titration flask.
Add 20 mL of dil. H2SO4.
Note the initial reading on the burette and start adding KMnO4 solution from the burette
into the titration flask till light pink colour appears.
Note the final reading on the burette and find the volume of KMnO4 solution used.
Repeat the titration to get three concordant readings
Observation Table
S.No. Burette reading Volume of KMnO4
used Initial Final
1
2
3
48
LMCHE010
Calculations:
Step 1 To calculate the molarity of ore solution
Let the volume of KMnO4 solution used be = x mL
Applying the molarity equation; i.e.
M1V1
n1 =
M2V2
n2
(Mohr salt) (KMnO4)
n1 = 5 n2 = 1 (from balanced chemical equation)
M1×20
5 =
1
100 × x
1
Molarity of iron in ore solution (M1) = x/400 M
Step 2 To calculate the strength of iron in ore solution
Since, Strength = Molarity × Molecular mass
Therefore strength of iron in ore solution = x/400 × 56
= y g/L
Step 3 To determine percentage of iron
Percentage of iron = y/20 x 100
Result: The percentage of iron is z%
Parameters: NA
Relationships to be determined: NA
Graphs/Plots: NA
Error Analysis: NA.
Cautions:
i. Don’t hold the pipette from the bulb.
ii. Don’t rinse the titration flask.
iii. Don’t blow off the last drop from the pipette.
Requirement for Lab Technician:
1. M/100 KMnO4
2. Mohr salt solution (20g/L)
3. Dil. H2SO4
49
LMCHE010
Date of Performance: ________ Worksheet of the student Registration No.______________
Aim: To determine the percentage of iron in the given ferrous alloy by potassium permanganate
method.
Observation Table:
S.No. Burette reading Volume of KMnO4
used Initial Final
1
2
3
Calculations:
Results and Discussion:
Error Analysis:
Learning Outcomes (what I have learnt): to be written by the students in 50-70 words.
50
LMCHE010
To be filled in by faculty
S.No Parameter (Scale from 1-10, 1 for
very poor and 10 excellent)
Marks Obtained Maximum
Marks
1 Understanding of the student about the
procedure/apparatus.
20
2 Observations and analysis including
learning outcomes
20
3 Completion* of experiment, Discipline
and Cleanliness
10
Signature of Faculty Total marks Obtained
51
LMCHE010
EXPERIMENT NO. 10
Aim: To prepare phenol formaldehyde resin (bakelite).
Equipments to be used: Beaker, glass rod, funnel and filter paper
Chemicals used: Formaldehyde (40%), conc. H2SO4, distilled water, Glacial glacial acetic acid
and phenol.
Learning Objectives:
i. To understand the concept of condensation polymerization: It is the one which is
formed by combination of monomers accompanied by release of small molecules like
H2O and NH3.
ii. To study the preparation of Bakelite:
Bakelite formation involves the following reactions
Procedure:
Place 5 mL of glacial glacial acetic acid and 5 mL of 40% formaldehyde solution in a 500
mL beaker.
Add to it 2 grams of phenol with continuous stirring.
Add a few drops of conc. H2SO4 with constant stirring.
A pink solid plastic mass appears in the beaker.
Wash the solid mass with water and dry it in the folds of filter paper.
52
LMCHE010
Calculate the yield of the product.
Required Results:
The yield of bakelite resin is __________ g
Parameters: NA
Relationships to be determined: NA
Graphs/Plots: NA
Error Analysis: As the polymerization is taking place theoretical yield cannot be
calculated. The expected yield is 2g.
Cautions:
i. While adding conc. H2SO4, it is better to stay little away from the beaker, since the
reaction sometimes becomes vigorous.
ii. The reaction mixture should be stirred continuously.
Requirement for Lab Technician:
1. 40% Formaldehyde
2. Phenol
3. Conc. H2SO4
4. Glacial acetic acid
53
LMCHE010
Date of Performance: ________ Worksheet of the student Registration No.______________
Aim: To prepare phenol formaldehyde resin (bakelite)
Observations:
Results and Discussion:
Error Analysis:
Learning Outcomes (what I have learnt): to be written by the students in 50-70 words.
To be filled in by faculty
S.No Parameter (Scale from 1-10, 1 for
very poor and 10 excellent)
Marks Obtained Maximum
Marks
1 Understanding of the student about the
procedure/apparatus.
20
2 Observations and analysis including
learning outcomes
20
3 Completion* of experiment, Discipline
and Cleanliness
10
Signature of Faculty Total marks Obtained
54
LMCHE010
EXPERIMENT NO. 11
Aim: To determine carbon monoxide content in emission from petrol vehicle.
Equipments to be used: Old newspaper, plastic bag, rubber band or twist tie, tape, scissors,
carbon monoxide detector and test automobile
Learning Objectives: (i) The purpose of the experiment is to determine the carbon monoxide
content.
(ii) Student will be able to get an idea about how carbon monoxide is detected at various
pollution control centers and how much is the toxicity level.
(iii) Student will be able to compare the level of carbon monoxide emission from various petrol
vehicles.
Outline of the procedure:
(I) Collection of the exhaust sample:
Cut a 2-3mm hole toward the bottom of the plastic bag. Using a permanent marker,
make a circle around the hole in the bag.
Place a small piece of tape over the hole and make sure it is secure. Fold the end of
the tape onto itself to create a small tab.
Wrap the outside of the tailpipe with newspaper without blocking the exhaust.
Compress the bag to remove all of the air from it and make sure the tape over the
sampling hole is secure before collecting the sample.
Hold the plastic bag against the newspaper that is wrapped around the tailpipe.
Start up the exhaust source while another person is ready to collect the sample of
exhaust and twist the bag closed once it fills with the car exhaust by tying a rubber
band.
(II) Testing the sample
Carefully pull back the tape covering the sampling hole and insert the carbon
monoxide detector into the bag.
Keep the detector inserted in the bag till it beeps.
Note the reading on the detector.
(III) Repeat the procedure for other sources.
55
LMCHE010
Observations:
Automobile source Carbon monoxide level (ppm)
Required Results: The level of carbon monoxide is highest in _______________ and
lowest in __________________.
Parameters: NA
Relationship: Between levels of carbon monoxide in exhaust from various petrol vehicles.
Graphs: NA
Error Analysis: NA
Cautions:
i. Exhaust should be collected carefully.
ii. Remember to cover the hole with the tape before collecting the exhaust.
iii. Keep you face away from the exhaust source.
Requirement for Lab Technician:
1. Carbon monoxide detector
2. Automobile exhaust
3. Rubber band
4. Tape
5. Polythene bag
56
LMCHE010
Date of Performance: ________ Worksheet of the student Registration No.______________
Aim: To determine carbon monoxide content in emission from petrol vehicle.
Observation table:
Automobile source Carbon monoxide level (ppm)
Results and Discussion:
Learning Outcomes (what I have learnt): to be written by the students in 50-70 words
To be filled in by faculty
S.No Parameter (Scale from 1-10, 1 for
very poor and 10 excellent)
Marks Obtained Maximum
Marks
1 Understanding of the student about the
procedure/apparatus.
20
2 Observations and analysis including
learning outcomes
20
3 Completion* of experiment, Discipline
and Cleanliness
10
Signature of Faculty Total marks Obtained
57
LMCHE010
EXPERIMENT NO. 12
Aim:To determine the amount of Dissolved Oxygen (DO) in the given water sample.
Equipments to be used: 300 mL BOD bottles, titration flask, pipette, burette, beakers, glass rod, funnel and burette stand
Chemicals used: Manganous sulphate, Alkali-iodide-azide, Concentrated H2SO4, Starch
solution, 0.025M Sodium thiosulphate and Potassium iodide
Learning Objectives:(i) To learn the importance of Dissolved oxygen as the measure of water
contamination.:The concentration of Dissolved Oxygen (DO) in natural water and wastewater
is a function of the temperature of the air and water, the degree of hardness of the water, and
the demand for oxygen in the body of water. The solubility of oxygen increases with decreasing
water temperature (oxygen solubility in water is inversely proportional to temperature). DO is
an important parameter in wastewater treatment processes, most notably when dealing with an
activated sludge system.
(ii) To make the students learn about the reactions taking place in this method:
Divalent manganese salt in solution is precipitated by alkali to manganese hydroxide
MnSO4 + 2KOH → Mn(OH)2 + K2SO4 In alkaline solution, dissolved oxygen is oxidized to form trivalent or higher valency hydroxide
2Mn(OH)2 + O2 → 2MnO(OH)2
Iodide ions reduce hydroxides to stable divalent ion by liberating equivalent amount of iodine.
MnO(OH)2 + 2KI + H2O → Mn(OH)2 + I2 + 2KOH
Thiosulphate solution is used with starch indicator, to titrate iodine.
I2 + 2S2O32-
→ S4O62-
+ 2I-
The Iodine is equivalent to dissolved oxygen present in the sample.
Indicator: Freshly prepared starch
End point: Blue to colourless
Outline of the procedure:
Fill a 300mL BOD bottle with the sample to be analyzed.
Pipette out 2 mL of manganous sulphate.
Pipette out 2 mL of alkali-iodide-azide.
Fix the stopper and invert the bottle several times to mix.
Allow the precipitates to settle in the solution to about half the volume of the bottle.
Invert the bottle several times to mix the precipitates back into the solution.
Allow the precipitates in the solution to settle to about half the volume of the bottle.
58
LMCHE010
After settling, add 1 mL concentrated sulphuric acid along the sides of the bottle, fix the
stopper and gently invert several times. Continue until the precipitate has dissolved back
into solution.
If a brown colour develops, dissolved oxygen is present in the sample. If no colour
develops or it is very faint, it may be appropriate to obtain another sample at this time to
ensure that there has not been an error in the sample preparation.
Titration
Take 200 mL of the above sample in a 500mL titration flask.
Fill the burette with standard sodium thiosulphate solution (0.025M)
Titrate the sample by adding sodium thiosulphate solution dropwise till solution of the
flask turns pale yellow.
Add 2-3 drops of starch solution and continue titrating dropwise until the disappearance
of the blue / purple colouration.
Note the volume used for thiosulphate used.
S.No. Burette reading
Volume used Initial Final
1
2
3
Calculations: When a 200mL sample is used, 1mL of sodium thiosulphate solution (0.025M)
is equivalent to 1mg/L Dissolved Oxygen in the sample.
(If 8.7mL of sodium thiosulphate was used, then DO of the sample is 8.7mg/L).
Result: The value of dissolved oxygen in the given sample of water was found to be mg/L.
Parameters: NA
Relationships to be determined: NA
Graphs/Plots: NA
Error Analysis: NA.
Cautions:
i. Always add concentrated H2SO4 in small amounts, along the sides of the bottle.
ii. End point should be noted carefully.
iii. Don’t blow off the last drop of the pipette.
59
LMCHE010
Requirement for Lab Technician:
1. Waste water sample
2. Manganous sulphate
3. Alkali-iodide-azide
4. Conc. H2SO4
5. Starch solution
6. Potassium iodide solution
7. 0.025M Sodium thiosulphate
60
LMCHE010
Date of Performance: ________ Worksheet of the student Registration No.______________
Aim: To determine the amount of Dissolved Oxygen (DO) in the given water sample.
Observation Table:
S.No. Burette reading
Volume used Initial Final
1
2
3
Mean volume :________________ml
Calculations
Results and Discussion:
Error Analysis:
Learning Outcomes (what I have learnt): to be written by the students in 50-70 words.
61
LMCHE010
To be filled in by faculty
S.No Parameter (Scale from 1-10, 1 for
very poor and 10 excellent)
Marks Obtained Maximum
Marks
1 Understanding of the student about the
procedure/apparatus.
20
2 Observations and analysis including
learning outcomes
20
3 Completion* of experiment, Discipline
and Cleanliness 10
Signature of Faculty Total marks Obtained