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Transcript of Molecular Biology Lab
8/17/2019 Molecular Biology Lab
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Kristin Moser
Pre-Lab No. 2
Solutions, Acids, & Bases
The pH Scale
Group 1
Section B1
Joanne Park !u"ust Tan Jin" #an
$ate% &'(1)(1)
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!bstract
The ob*ecti+e o, this eperient is to un/erstan/ olarit0 o, solutions an/ be able to test their
pH +alue. Besi/es testin" aci/s an/ bases bu,,ers ill also be teste/ to /eterine their
e,,ecti+eness on such solutions. ertain coercial antaci/s use/ ,or e/icinal purposes ill be
teste/ to pro+e their e,,ecti+eness.
Materials
• Test tubes
• 3ine"ar
• Ski ilk
• !pple *uice
• Grape,ruit *uice
• Butterilk
• Black co,,ee
• Sprite
• Househol/ bleach
• Miture o, Sprite an/ bakin" so/a
• 1& M h0/rochloric aci/
• &.1 M h0/rochloric aci/
• $istille/ ater
• Tap ater
• Phosphate sul,ur
• Nal
• Brocresol purple in/icator
• pH papers
•
Para,il• Late "lo+es
• !ntaci/
• Pipettes
• Lab oat
• Pen
• Paper
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Proce/ure
Measurin" the pH o, li4ui/s%
• Measure the ,olloin" li4ui/s usin" a ,resh pH paper ,or each li4ui/%
o 3ine"ar
o Ski ilk
o !pple *uice
o Grape,ruit *uice
o Butterilk
o Black co,,ee
o Sprite
o Househol/ bleacho Miture o, Sprite an/ bakin" so/a
o 1& M h0/rochloric aci/
o 1.& M h0/rochloric aci/
o $istille/ ater
o Tap ater
• 5se the ,olloin" e4uation to check the easureents o, the h0/rochloric aci/%
Test the abilit0 to o, bu,,ers to stabili6e pH%
• Label ,our test tubes ,or the ,olloin" substances% 7ater &.1 M Nal Ski ilk &.1 M
Phosphate sul,ur.
• !// )L o, each solution into the appropriate test tubes.
•Measure each solution8s pH +alue an/ recor/ it in a table.
• 9i+e /rops o, aci/ shoul/ no be a//e/ to &.1 M Hl. No "entl0 i the solution b0
co+erin" the top o, the test tube ith para,il an/ in+ertin" the tube.
• :etest the pH o, the ne solution.
• :epeat a//in" aci/ to the rest o, the substances an/ test its ne pH.
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Test the e,,ecti+eness o, coercial antaci/s%
• $eterine one /ose o, the antaci/ an/ use a ortar an/ pestle to turn the antaci/ into a
po/er.
• $issol+e the antaci/ po/er into 1&&L o, /istille/ ater.
• Place 1&L o, the ater an/ antaci/ solution into a test tube.
• 9our /rops o, brocresol purple in/icator to the test tube.
• Mi the solution "entl0 b0 placin" para,il o+er the top o, the test tube an/ in+ertin" the
tube.
• &.1 M Hl shoul/ no be a//e/ one /rop at a tie to the tube an/ ie/ a,ter e+er0
/rop. $o this until the solution turns 0ello.
Theoretical Pre/ictions
!ll the substances liste/ belo ill ha+e their pH +alue teste/. These are 0 pre/ictions on hat
their pH +alue ill be hen teste/ in the lab. Soe o, these +alues ; recei+e/ ,ro research or
the lab anual.
3ine"ar < = >3o/opich 2&&?@
Ski ilk - A
!pple *uice <
Grape,ruit *uice - 2
Butterilk - A
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Black co,,ee- ) >3o/opich 2&&?@.
Sprite - =
Househol/ bleach-12.)
Miture o, Sprite an/ bakin" so/a < ?
1& M h0/rochloric aci/ - 1&
1.& M h0/rochloric aci/ - '
$istille/ ater -? >pH 3alue 2&&'@
Tap ater < A.?
Since broocresol purple is use/ to /etect aci/s ; think that the solution a/e ith the antaci/
ill pro+e ine,,ecti+e >National enter ,or Biotechnolo"0 ;n,[email protected] broocresol purple
ill ake the solution turn 0ello there,ore /etectin" the presence o, an aci/. This ill sho
ho coercial antaci/s /o not ork as ell as e a0 think.
Lab Cuestions
1
2)" o, sucrose
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2)" o, calciu chlori/e
)" o, calciu chlori/e
2
1.A2) " o, Nal
1.A2)" o, Nal
?A" o, sucrose
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.&?A" o, sucrose
12.=2" o, calciu chlori/e
." o, calciu chlori/e
AD." o, su"ar
.&?= oles o, su"ar. &.&&&1A M solution.
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.22 oles o, calciu chlori/e. .&&& M solution.
)&&L o, sucrose solution
=
12) L o, sul,uric aci/.
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2&L stock solution E D& L ater.
=&&L o, ater
7ork ite/
3o/opich $.S. Introduction to Cellular and Molecular Biology Lab. Ne-#ork% McGra-Hill
2&&? p. 2&.
PH 3alue o, oon Substances. >2&&'@. :etrie+e/ Septeber 1) 2&1).
National enter ,or Biotechnolo"0 ;n,oration. Pubhe opoun/ $atabaseF ;$D2?=
>:etrie+e/ Sept. 1) 2&1)@.
Kristin Moser
Post-Lab No. 2
Solutions, Acids, & Bases
The pH ScaleGroup 1
Section B1
Joanne Park ubair Hale
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$ate% &'(22(1)
;n-lass Proce/ure
9or the ,irst part o, the eperient /i,,erent solutions ere teste/ to /eterine their pH
+alue. These solutions ere ,oun/ in correspon/in"l0 labelle/ beakers. eraic palettes ith
three ros an/ ,our coluns ere han/e/ out. Stras ere use/ throu"h capillar0 action to place
three saples o, each solution in one colun. Since each "roup as "i+en to ceraic platters
enou"h ,or ei"ht solutions this as repeate/ three ties. ;n the ,irst ro a hal, o, a blue litus
paper as place/. ;n the secon/ ro a hal, o, a re/ litus paper as place/. ;n the thir/ ro a
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hal, o, a pH strip as place/. !n0 chan"e in color ,or either litus paper as recor/e/ in a table
>,oun/ in results@. Net the pH strips color as teste/ a"ainst the ke0 on the pH strip container.
The secon/ part o, the eperient re4uire/ /istille/ ater &.1M Nal ski ilk an/
&.1M phosphate bu,,er o, ) L +olue each to be put in separate test tubes. The initial pH o, the
solutions as taken usin" a pH strip an/ recor/e/. Ten /rops o, aci/ as a//e/ to each solution
an/ ie/. The pH a,ter as taken usin" a pH strip an/ recor/e/.
;n the thir/ an/ ,inal part o, the eperient the e,,ecti+eness o, certain coercial
antaci/s ere teste/. 9i+e L o, rea/0-a/e solutions o, !lka-Selt6er hite Tus an/ bakin"
so/a ere a//e/ to separate test tubes. 9our /rops o, brocresol purple in/icator as a//e/ to
each test tube an/ ie/. The initial colors o, the solutions ere note/. Then aci/ as a//e/ one
/rop at a tie an/ ie/ a,ter e+er0 /rop until the solution turne/ 0ello or 1&& /rops as
reache/. The nuber o, /rops as recor/e/.
:esults
Proce/ure 1%
T% Theoretical B% Be,ore !% !,ter N!% Not a+ailable
Iperiental
:ea"ent
Blue Litus Paper
>chan"es i, aci/ic@
:e/ Litus Paper
>chan"es i, basic@
pH strip
Pre/ictions(:esults T B ! T B ! T B !
3ine"ar N! Blue :e/ N! :e/ :e/ = & A-?
Ski Milk N! Blue Blue N! :e/ :e/ A & ?-D
!pple Juice N! Blue :e/ N! :e/ :e/ & A-?
Grape,ruit Juice N! Blue :e/ N! :e/ :e/ 2 & A-?
ranberr0- N! Blue :e/ N! :e/ :e/ N! & )-A
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poe"ranate Juice
Butterilk N! Blue :e/ N! :e/ :e/ A & A-?
Black o,,ee N! Blue Blue N! :e/ :e/ ) & A-?
Black Tea N! Blue Blue N! :e/ :e/ N! & A-?
Green Tea N! Blue Blue N! :e/ :e/ N! & A-?
Sprite N! Blue :e/ N! :e/ :e/ = & )-AHousehol/ Bleach N! Blue N! N! :e/ N! 12.) & N!
Miture o, bakin"
so/a an/ Sprite
N! Blue Blue N! :e/ Blue ? & '-1&
Bakin" So/a N! Blue Blue N! :e/ Blue N! & '-1&
1& M Hl N! Blue :e/ N! :e/ :e/ 1& & -)
1.& M Hl N! Blue :e/ N! :e/ :e/ ' & -)
.&1 M Hl N! Blue :e/ N! :e/ Blue N! & )-A
$istille/ 7ater N! Blue Blue N! :e/ :e/ ? & A-?
Tap 7ater N! Blue Blue N! :e/ :e/ A.? & A-?
Proce/ure 2%
;nitial pH pH a,ter aci/
$istille/ 7ater ? =-
&.1M Nal A-? =-
Ski Milk A-? )-A
&.1M Phosphate Bu,,er A-? A-?
Proce/ure =%
Solution Nuber o, $rops o, !ci/
!lka-Selt6er )
7hite Tus '
Bakin" So/a 1&&
Lab Photos%
Proce/ure 1
Figure 1: Procedure 1: Cronberry-pomegranate juice, buttermilk, cofee, and black tea
Figure 2: Procedure 1: Green tea, Sprite, 01!bleac", Sprite and baking #oda
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Proce/ure 2%
Figure $: Procedure 1: %ap &ater and di#tilled &ater Figure ': Procedure 1: (aking #oda, 10m) *Cl,01 m) *Cl, and 001 m) *Cl
Figure +: Procedure 1: inegar, #kim milk, apple juice,and graperuit juice
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Proce/ure =%
Lab Notes%
pH after
acid: 0.1
phospha
pH after
acid: WaterInitial pH:
0.1M
phosphate
Initial pH:
Skim milkInitial pH:
0.1M NaClInitial pH:
Water pH after
acid: Skim
milk
pH after
acid: 0.1M
NaCl
Figure .: Procedure ': (aking #odaater 100 drop# o acid
Figure /: Procedure ': lka-#elteater + drop# o acid
Figure : Procedure ': %um# ater 3drop# o acid
ums solution
initial color
!akin" soda
solution initiacolor
lka$selt%er
olution initial
olor
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onclusion
9or proce/ure 1 o, the eperient un,ortunatel0 not an0 pre/ictions ere a/e to
copare the results to. But the pre/ictions that ere a/e /i/ not pro+e correct. !ccor/in" to
3o/opich the pH o, +ine"ar shoul/ ha+e been aroun/ = >2&&?@. Base/ on proce/ure 1 o, the
eperient +ine"ar /i/ turn blue litus paper re/ pro+in" it as an aci/F hoe+er the pH
shoe/ a color close to oran"e in/icatin" a pH in the ran"e o, A-?. !nother stran"e result that
occurre/ as that &.&1M o, Hl turne/ blue litus paper re/ an/ re/ litus paper blue. !s an
aci/ &.&1M o, Hl as suppose/ to turn blue litus paper re/ but not suppose/ to turn re/
litus paper blue. Base/ on The pH Scale it akes sense that &.&1M o, Hl is sli"htl0 ore
basic than .1M or 1.&M o, Hl >Tun" 2&1=@. ;t has a saller concentration o, HE as the
olarit0 /ecreases. !lso the househol/ bleach as unable to "et accurate results because o,
bleach8s capabilit0 to reo+e color ,ro solutions. 7hen blue litus paper re/ litus paper
an/ the pH strip ere place/ in the househol/ bleach the color as reo+e/ an/ the papers
appeare/ hite.
;n proce/ure 2 the reason there as such a stron" chan"e in pH ith both the /istille/
ater an/ the Nal solution is because both contain H2 olecules hich ill /issociate an/
increase its HE concentration ith the a//e/ HE concentration ,ro the Hl. Since the ain *ob
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o, a bu,,er is to ,in/ an e4uilibriu beteen the HE an/ H- concentration it akes sense that
the &.1M phosphate bu,,er as una,,ecte/ b0 the a//ition o, Hl. The pH +alue reaine/
relati+el0 the sae there,ore the bu,,er /i/ its *ob ell.
;n proce/ure = the !lka-selt6er pro+e/ least e,,ecti+e hen onl0 a,ter ) /rops /i/ the
solution turn 0ello. The hite Tus as the secon/ least e,,ecti+e ith onl0 ' /rops until it
turn 0ello. The bakin" so/a as the ost e,,ecti+e antaci/. !,ter 1&& /rops >hich as the
aiu alloe/@ the bakin" so/a still /i/ not turn 0ello.
Sources o, Irror
7hile testin" the pH +alue o, bleach in proce/ure 1 the results ere inconclusi+e because the
bleach bleache/ the paper hite. This coul/ not ha+e been a+oi/e/ because the eperient
re4uire/ the use o, a pH strip an/ litus paper not a pH eter.
7hen Hl as a//e/ to /istille/ ater &.1M Nal phosphate bu,,er an/ ski ilk 1& /rops
ere suppose/ to be a//e/. ! /rop is not a speci,ic easureent an/ coul/ +ar0 per person so
there as probabl0 a sall +ariation in the aount o, aci/ a//e/ to each test tube. ;, this
eperient as ore precise this a0 ske the results but it shoul/n8t ha+e ha/ an0 e,,ect on
the pH +alues recor/e/ in the en/.
Lab Cuestions
A
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Bakin" so/a neutrali6es the ost aci/ an/ !lka-selt6er neutrali6es the least.
This 4uestion can8t be ansere/ because the nuber o, tablets use/ is unclear. Solutions use/
ere pre-a/e.
Tus < calciu carbonate
!lka-selt6er- !nh0/rous citric aci/ aspirin so/iu bicarbonate
Bakin" so/a- so/iu bicarbonate
;t appears that !lka-selt6er an/ bakin" so/a ill ork better as antaci/s because the0 contain
H- in their olecular structure hich is knon as the basic olecule. ;t also sees like Tus
oul/n8t ork e,,ecti+el0 unless it coes in contact ith ater because than the o0"ens ,ro
the calciu carbonate can bon/ ith the h0/ro"ens ,ro ater to ,or H-.
?
!lka-selt6er per,ore/ orse than epecte/. ;t as the eakest o, the antaci/s. The Tus
solution hoe+er per,ore/ as epecte/ because it as /issol+e/ in ater hich a/e it ore
e,,ecti+e. The bakin" so/a as the ost e,,ecti+e.
7hen /issol+e/ in ater these pro/ucts break apart ater to create a lar"e concentration o, H-
olecules hich balances out the lar"e aount o, HE olecules in the aci/.
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7ork ite/
asi/0 :. 9re0 :. >1'''@. Bloo/ Seat an/ Bu,,ers% PH :e"ulation $urin" Iercise. :etrie+e/
Septeber 21 2&1).
Tun" I. Tsao S. Sin"h $. Gorle0 P. >2&1= ctober 2@. The pH Scale. :etrie+e/
Septeber 21 2&1).
3o/opich $.S. Introduction to Cellular and Molecular Biology Lab. Ne-#ork% McGra-Hill
2&&? p. 2&.