Unit 6 Mole and Stioch.. Unit 6 Starts Tues: Panther Drill Review Problem 5-10 min Review Quiz Early...
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Transcript of Unit 6 Mole and Stioch.. Unit 6 Starts Tues: Panther Drill Review Problem 5-10 min Review Quiz Early...
Unit 6 Mole and Stioch.
Unit 6 Starts
Tues:Panther Drill Review Problem5-10 min ReviewQuizEarly Finish = Word Search
Panther DrillPotassium Chlorate reacts to form Potassium chloride
and oxygen gas. Write the equation for this reaction, balance it, and state what type of reaction it is.
Skeleton Equation:KClO3 KCl + O2
Balanced ____KClO3 ___ KCl + ____O232 3
Wednesday
PD= Converions Modeling: How to us Dim AnaylisisPractice
TODAYToday: We will practice using dimensional
analysis to convert between units. This is a review of what we did in
Panther Drill
Convert 5 feet into cm. 1 inch = 2.54 cm Set up the conversions using dimensional analysis.
5ft x 12 in 2.54 cm = 1 ft 1 in
152.4 cm
Active Inspire Practice
Thurs
Panther DrillGuess how many activityPairs will list ways items are quantified other
than by the each.Notes Discussion on the moleExit ticket “Explain the mole is similar to a
dozen.”
Panther DrillThere are 50
paperclips in a box and 20 boxes in a case. If I have 2750 paper clips how many cases do I have?
TODAY1. 1 more dimensional
analysis problem2. Explain how to count
large numbers of small items w/out counting them individually
3. Meet the Mole.
Get with your partner
Make a list of different units there are to count items. EXAMPLES
Ream: 500 pieces of paper.
A gross: A gross of something = 144 of an item
Hint: How are things sold in the supermarket.
Active inspire
List our lists
1 Intro
We have seen how much easier it is to count small items such as paper clips by a larger unit rather than by the each.
That was easy compared to if you had to count the number of atoms of aluminum in a paper clip.
2 IntroChemist often have to find out how many atoms
or particles of an element or compound are in a sample. This would be nearly impossible with out a unit that would count a very small things w/ out counting each particle individually.
Chemists use the Mole
NO not either of these
3 IMPORTANT!!A mole or (mol) is the SI or scientific unit for
counting particles, atoms, or molecules.
The mole was defined in 1811 by an Italian scientist and lawyer named Avogadro. He figured out that there was 602,213,670,000,000,000,000,000 particles of anything in 1 mole of that item.
We use scientific notation = 6.02x 1023
This is called Avogadro’s number
4Look at the test tubes being past around you will
see that you can have moles of different kinds of particles.
Tube 1 has 1 mole of copper atomsTube 2 has 1 mole of water moleculesTube 3 has 1 mole of salt moleculesBeaker has 1 mole of sugar moleculesWhat do you notice about the moles of the
items, how are they different?
5Think about it this way
A mole of sugar molecules can look larger than a mole of salt molecules (even though they both contain 6.02x 1023 particles) because the molecules of sugar are larger than a salt molecules.
Just like a dozen marbles looks larger than a dozen than a dozen pennies, but the each have 12 items in them.
EXIT TICKETExplain the mole is similar to a dozen.
NAME:
Monday
Panther Drill
In your own words define a mole as it is used in chemistry.
What’s in a Mole
Remember the mole is the # of particles in a sample.
Avogadro's # says there are 6.02 x 1023 particles of any thing in a mole of a sample being measures
There are 3 different representative particles that a mole can count: Atoms, Molecules, and Formula units
In an element (H,Cl, Zn ect) it represents atoms
In a molecular compound such as water, sucrose, and carbon dioxide, the mole counts molecules.
In an Ionic Compound like NaCl, or Magnesium Oxide, the mole counts formula units
What is the representative particle in the following?
1. LiCl2. C12H22O11
3. BeH2
4. Mg5. PCl5
ATOMS
Formula Units
Formula UnitsMolecules
Molecules
Conversion Cheat SheetOn the index card provided or somewhere you won’t
lose it write down the following:
You can use this when doing conversions
Side 2 of Index Card
# of Moles = # of particles X ___1 mole __.
6.02 X 1023
particles
Finding the number of moles
Finding the number of particles
# of Particles = # moles X 6.02 X 1023 particles 1 mole
Side 1 of Index Card
Panther DrillWhat is the representative particle being counted by
the following:1. NaCl2. CO2
3. Fe4. H2SO4
Conversion moles to particlesConvert 3.50 moles of Sucrose to # of particles
3.50 moles x X 6.02 X 1023 particles = 1 mole
DO THE MATH:2.11 x 1024
Conversion (Particles to Moles)Convert 4.5 x 1024 atoms of Iron to moles of iron
What Conversion factor?# of Moles = # of particles X 1 mole ___.
6.02 X 1023 particles
Moles = 4.5 x 1024 atoms X 1 mole ___.
6.02 X 1023 atoms
DO THE MATH: 7.48 moles Fe
You practice now
You and your partner practice now
Partner A
1. 2.5 moles of Zn to # atoms
2. 2.9 x 1024 formula units of NaCl to moles
Partner B
1. 4.0 moles of CO2 to # molecules
2. 7.2 x 1023 formula units of Li2S to moles
Tuesday
Panther Drill
1) Convert 3.50 moles of Salt to # of particles
2) Which types of particles are you counting (atoms, molecules or formula units) in the compound salt?
Work on some mole conversions on your own
Get a WS and complete all 5 problems
Examples Moles = 4.5 x 1024 atoms X 1 mole _ = 7.48 moles Fe
6.02 X 1023 atoms# Particles: 3.50 moles X 6.02 X 1023 part. =
1 mole2.11 x 1024
molecules
Moles and Mass
Panther Drill
If 1 dozen eggs weighs 2.3 pounds, determine how much 5.5 dozen weigh.
5.5 doz1
2.3 lb 1 doz
X 5.5 X 2.3 lbs = 12.65 lbs=
Mass and the mole in single elements
A mole always contains the same number of particles; but moles of different substances have different masses.
Think about it like this: A mole is like a dozen.
A dozen bowling balls would have a different mass than a dozen eggs, but each one still has 12 items in it.
Lets look at the element Carbon1 mole of Carbon = 6.02 x 1023 atomsCarbon has an molar (atomic)mass
of 12.01 g
The mass of 1 mole of a substance = the molar mass
**The mass of 1 mole of an element can be found on the periodic table
12C
Carbon 12.01
Converting from # of moles to massLets look at a dozen jellybeans
1 dozen jellybeans = 35 gramsTHIS BECOMES OUR CONVERSION FACTOR
How many grams are there in 5 dozen jelly beans?
1 dz jelly beans5 dz Jellybeans 35 grams = __________ g175
Converting From Moles to Mass
The mass of 1 mole of carbon = 12.01 g
How many grams are there in 8 moles of carbon?
12.01 g C8 moles of C x1 mol C
=____________ g Cu96.08
Moles to Mass (2)
The mass of 1 mole of copper = 63.546 g
How many grams in 4 moles of copper:4 mol Cu = =____________ g Cu
1 mol Cu262.1865.546 g Cu
Converting Mass to Moles
You have 7.6 Grams of Boron (Atomic/Molar Mass 10.81)
Convert grams of Boron to moles of BoronConversion factor: 1 mole of boron = 10.81 gramsHow would you set up the conversion fraction?7.6 g B X 1
1 mol B10.81 g B
= ________mol B0.703
You Try
Partner A and BPARTNER A
How many moles are in 15 grams of lithium?
Partner BHow many grams are in 2.4 moles of sulfur?
Each student do their own problem and then explain how they got the answer to their partner
Partner A
How many moles are in 15 grams of lithium? (molar mass of lithium is 6.94 g/mole)
15 grams Li x
2.16 moles
1 mole = 6.94 grams
15/7 moles Li
Partner B
How many grams are in 2.4 moles of sulfur?molar mass of sulfur is 32 g/ mole
2.4 moles x 32.065 grams S 1mole S
76.956 g S
Practice Moles to Grams of AtomsHow many moles are in 22 grams of argon?
How many grams are in 88.1 moles of magnesium?
How many moles are in 2.3 grams of phosphorus?
How many grams are in 11.9 moles of chromium?
How many moles are in 9.8 grams of calcium?
Practice Moles to Grams of AtomsHow many moles are in 22 grams of argon?
How many grams are in 88.1 moles of magnesium?
How many moles are in 2.3 grams of phosphorus?
How many grams are in 11.9 moles of chromium?
How many moles are in 9.8 grams of calcium?
MONDAY
Panther DrillHow many moles are in 198.6 grams of potassium?198.6g K x
How many grams are in 12.3 moles of nitrogen?12.3 mol N
1mol .39.1 g K ___________ moles K
14.01 g N 1 mol N
___________ g N
5.08
172.32
Converting Grams to Moles to Particles2 ways to do this
1. Convert from grams to moles then separately convert from moles to particles.Example: Convert 41.7 grams of boron to atoms of
Borona) 41.7 g B = __________ mole B
b) 3.86 mol B =_________ atoms B
1 mole B 10.81 g Bx 3.86
6.02 x 1023 atoms B
1 mole B x 2.32x 1024
2. Do all the conversions in the same equationExample: Convert 41.7 grams of boron to atoms of
Borona) 41.7 g B
=_________ atoms B
Converting Grams to Moles to Particles
1 mole B 10.81 g B
x x6.02 x 1023 atoms B
1 mole B = # atoms B
41.7 x 6.02x1023
10.81 2.32x 1024
Try This OneHow many atoms are in 2.13 grams of Helium
INSERT ACTIVE- INSPIRE HERE
Vitamin Lab Activity
You need to get your partner assignmentsYou need to get a lab sheet for your groups and
get the material on the lab sheet.Get to work
Tuesday
Continue lab activity and turn in at the end of the period.
Panther DrillCreate a simple flow
chart that shows the process of converting mass to moles, to atoms of an element. For each step, make sure to show the conversion fractions you would use to do that step Examples of flow chart
outline
Continue w/ Vitamin lab activity
Micrograms to grams
2mcg Mg x 1 gram1,000,000 mcg
Wednesday
P-drillFinish Vitamin Lab and turn in at end of the
period.Students finishing early will do extra credit
assignment converting grams to moles.Exit ticket thumbs up down on grams-moles-
particle converting of an element
Panther Drill (Review Material) 1. Which of the following elements has three valence
electrons?a) lithiumb) boronc) nitrogend) more than one of the above
2. Which of the following is not an acid?a) HNO3
b) CH3COOHc) H2SO4
d) All of these are acids
Thursday
Panther Drill
Find the mass of 1 mole of the following:
Carbon:
Phosphorus:
Iron:
Oxygen Gas:
12.01
30.97
55.85
From the periodic table we get 16.00Amu, but Oxygen is diatomic so in the Real word it would be 16 x 2 = 32.00
Formula Weight or MassFormula Weight is the total of all the atomic masses
for each element in the formula for a compound.
Formula mass, Molar mass, and Formula Weight are the same thing.
The formula mass or weight is like the atomic mass of a compound.
The mass of 1 mole of a compound = the formula mass or weight
ExampleDetermine the formula mass of 1 mole of Magnesium
Chloride?1. Write the chemical formula. (if it is not given)
Remember to “criss-cross” the charges to get the subscripts. (**Signs Drop off)
Magnesium Chloride Mg2+ Cl-1
2. Determine the atomic mass for each element.Mg= 24.31 g/mol ; Cl=35.45 g/mol
3. Look to see how many of each element there are in the formula.
MgCl2
Mg = 1 atom ; Cl = 2 atoms
=
Example (cont)
4. Multiply the number of atoms of each element in the formula by the atomic mass of each element.(Mg) 1 x 24.31 g = 24.31 g(Cl) 2 x 35.45 g = 70.90 g
5. Add up the results: 24.31 g + 70.90 g = 95.21 g
1 mole of MgCl2 = 95.21 g
The formula mass of MgCl2 = 95.21 g
70
A. 1 mole of K2O = ______g
B. 1 mole of antacid Al(OH)3 = ______g
Learning Check How many grams in 1 mole
71
A. 1 mole of K2O
K: 2 x 39.1g/mol =
O: 1 x 16g/mol =
B. 1 mole of antacid Al(OH)3
Al: 1 x 27.0 g/mole = O: 3x 16.0 g/mole =
H: 3 x 1.01 g/mole =
Solution
78.2g =94.2 g K2O
= 78.02 g Al(OH)3
48
16 g 78.2 + 16
3.03
27
27 + 48 + 3.03
Practice
Partner A:Molar mass of Na3P
Molar Mass of CH4O3S (Methanesulfonic acid)
Partner BMolar mass of AlCl3
Molar Mass of C6H12O6
Calculate Molar Mass
Complete the 5 problems on the 1/2 page WS and turn them in in the basket. You need to work by your self and you have 10 to 15 min to complete.
Write the Formula Mass for the following and Turn in when completed
1. NaF2. KGa3. Diphosphorus trioxide4. LiS2
5. Diphosphorus hexachlorine6. Al2O3
Write the Formula Mass for the following and Turn in when completed
1. NaF2. KGa3. Diphosphorus trioxide4. LiS2
5. Diphosphorus hexachlorine6. Al2O3
76
Prozac, C17H18F3NO, is a widely used antidepressant
that inhibits the uptake of serotonin by the brain. It has a molar mass of
1) 40.0 g/mole
2) 262 g/mole
3) 309 g/mole
EXIT TICKET
FridayStudents will learn to convert between grams
and moles of compoundsStudents will work on a comprehensive work
sheet that covers formula mass and converting from formula mass of a compound to moles of a compound.
Individual work will take all period
79
Prozac, C17H18F3NO, is a widely used antidepressant
that inhibits the uptake of serotonin by the brain. It has a molar mass of___________________?
Panther Drill
80
Prozac, C17H18F3NO, is a widely used antidepressant that
inhibits the uptake of serotonin by the brain. It has a molar mass of
17C x (12.01)=
18H (1.01) =
3F (19.0) =
1N (14.01) =
+ 1 O (16.0) =
Solution
309 .36 g/mole of Prozac
204.1718.18 57.0014.01
16.00
309 .36
Converting between Moles and Mass of a compound.
Done the same way as w/ elementsSame conversion Fractions but w/ compounds not
elements and molar mass instead of atomic mass
Grams x 1 mole of compound = # moles compound molar mass of compound
1) See what the problem gives you and see what it is asking for.
2) Determine the chemical formula & calculate the molar mass
3) Do the mathMass to moles: Molar mass on the bottom of the fraction and divide.Moles to mass: molar mass on top and
multiply
REMEMBER WHEN GOING MASS-MOLES WE
DON’T NEED 6.02 X 1023
Converting between Moles and Mass and moles to mass of a compound.
EXAMPLE Mass to MolesHow many moles are in 198 grams of water?
Step 1: See what you are given in the problem and what it wants you to answer.
198 grams H2O ; Wants Moles of H2OStep 2: Determine the chemical formula & calculate
the molar mass H: 2 x 1.08 O: 1 x 16.0
Molar Mass = 18.16 g/mole of water
Converting between Moles and Mass of a compound.
2.16 + 16
Converting between Moles and Mass of a compound
3. Multiply the mass you are given by 1 mole over the molar mass of water. Then simplify, the fraction that is left (divide the top number by the bottom. 198 g divided by 18.16 g = moles water)198 g of water x =
= _______ mole Water
1 mole water 18.16 g water
10.93
198 = 18.16
You Try
How many moles are in the 171.16 grams of Lithium Chloride?
EXAMPLE Moles to MassWhat is the mass of 4.5 moles of CO2
Step 1: See what you are given in the problem and determine the chemical formula of the compound.
Step 2: Calculate the molar massC x 1 = 1x 12.01 gO x 2 = 2 x 16 g
Molar Mass = 44.01 g/mole of CO2
Converting between Moles and Mass of a compound.
12.01 + 16
CO2
Moles to Mass (cont)EXAMPLE Moles to Mass
Step 3: Set up the equation by multiplying the # of moles given by the molar mass over 1 mole.
4.5 moles CO2 x
= 198.05 mol CO2
44.01 gramsCO2
1 mole CO2
= 4.5 x 44.01
Partner A / BPartner A:
You are given 5.46 moles of MgO how many grams do you have?
Partner B:You need to convert 164.4 grams of CaCl2 to moles.
When you are finished explain to each other how you got your answers and sign off on each others
work
Fri
Panther DrillOrganize your materials for your open notes quiz.Ask any questions you have.StudyIf the class is loud we will immediately start the quiz.After you turn your quiz in to me at the desk, pick up
a practicing percentages problem set.
Turn in panther drill from Tuesday, and any other work still out in the basket on the table.
Weds
Mon and Tues = Sub
Panther Drill % review
1. Mary has a monthly salary of $1200. She spends $280 per month on food. What percent of her monthly salary does she spend on food?
280/1200 x 100 = 23.33%
2. What is 98.3% of 23?
98.3%/100 .983 x 23 = 22.61
No Panther Drill for MondayWEDS CLASS WILL MEET IN MEDIA CENTER
Thursday
Percent Practice
Convert the following to fractions:1. 37%
2. .983
98.3/100
37100
Panther Drill
Definition• Percent can be defined as “of one hundred.”
100of
Percents Have Equivalents in Decimals and Fractions
20% .20 20100
15= = =
Decimal FractionFractionSimplifiedPercent
Always simplify fraction to lowest terms!!!
Remember These Equivalent Fractions
12143413
=
=
=
=
50%
25%
75%
33.3%
=
=
=
=
66.6%
20%
40%
60%
23152535
How to Find the Percent of a Whole Number
• The first thing to remember is “of” means multiply in mathematics.
of = x
Copyright © 2000 by Monica Yuskaitis
How to Find the Percent of a Whole Number
• Step 1 - When you see a percent problem you know when you read “of” in the problem you multiply.
25% of 200x
Copyright © 2000 by Monica Yuskaitis
How to Find the Percent of a Whole Number
• Step 2 – Change your percent to a decimal and then move it two places to the left.
25% x 200..
How to Find the Percent of a Whole Number
• Step 3 – Multiply just like a regular decimal multiplication problem.
200x .2550.00
Is/of = %/100
IS = % OF 100
IS x 100 = OF x %
Cross Multiple
Solve for what ever is unknown
Is/of (cont)26 is what % of 34?Step 1) See what you are
givenis = 26of = 34% = ????
Step 2: Set up: is/of = %/10026 = X34 100
Step 3: Isolate unknown and solve:Cross multiply: 34X = 2600Divide to isolate unknown 34X = 2600 34
X = 76.47
Quick Practice A/B Partner
Convert these to fractions:
1) 79%2) .553) 33.3%
Convert these to decimals:
1) 21% 2) 6/83) 66%
.21.75.66
79/10055/100 or 11/20
33/100Or 1/3
Quick Practice 2
Convert these to %:
1) 2/52) 2/103) .59344) .0265) 1.64
40%20%59.34%
2.6%164%
Practice.
Panther Drill Example 1. Homer has a box of assorted doughnuts.
3 of these doughnuts are chocolate. What percentage of Homer's doughnuts are chocolate? (note, we are talking about total number, not mass, in this case.)
Solution
number of chocolate doughnuts% of doughnuts that are chocolate = ------------- x 100 Total # doughnuts
3 % of doughnuts that are chocolate = ----------- x 100 12
.25 x 100 = 25% Chocolate
Percent composition
As we briefly discussed in the beginning of the year, percent composition is the amount of each element in (in %) a compound. Also called mass percent of a compound.
Mass % = mass of element in 1 mole of a compound X 100molar mass of compound
Mass % of H and O in WaterWhat is the % composition of Oxygen in water?Molar Mass H2O: 18.02 g
Mass of O in H2O: 16 g
Mass% O = (16 / 18.02) X 100Mass % O = 0.8879 X 100Mass % O = 88.79 Oxygen accounts for 88.79% of the mass of a
molecule of water
Mass % of H and O in WaterWhat is the % composition of Hydrogen in water?Molar Mass H2O: 18.02 g
Mass of H in H2O: [2 x 1.01] = 2.02 g
Mass% O = (2.02/ 18.02) X 100Mass % O = 0.1121 X 100Mass % O = 11.21 % Hydrogen accounts for 11.21% of the mass of a
molecule of water
Lets do a problem togetherWhat is the mass % of sodium in NaCl?
Partner A /BPartner A: Determine the mass % of Carbon and
Hydrogen in CH4.
Partner B: Determine the mass % of Phosphorus and Oxygen in PO3
Sign off on and check your partners work
Panther DrillDo this somewhere in your notes, I will be around to
check it.
What is the Mass% of each element in Sucrose:
C12H22O11
Panther Drill1. How does ionization energy and atomic radius
change as move to the right across and down the periodic table.
IE: As you move across a period, first ionization energy increases
As you move down a group, first ionization energy decreases.
AR: As you move down a group, atomic radius increases.
As you move left to right across a period, atomic radius decreases.
Work on Lab report
DUE WEDNESDAY at the beginning of class
Choices
• If you finish early, either work on the Chapter 11, pre-assignment OR use your knowledge of elements and the periodic table to complete the “Its Elementary” Chemistry March Madness assignment.
Real Bracket
Its Elementary Bracket RulesRound #
1. The element discovered first wins the game and moves on.
2. Ionization E the highest wins the game and moves on.
3. Element in the group w/ the highest group number wins and moves on.
4. Atomic Radius the highest wins the game and moves on.
Its Elementary Bracket RulesSemi-finals (final 4): Solve the riddles to determine the two
elements that will compete for the championship.
Finals:Fill in the blank on the your insruction
sheet to determine the winner
Chap 11 Pre-Assignment
Use the text book to complete the packet.
Panther Drill 1. List 3 things that you can observe that tell you a
chemical reaction or a chemical change has occurred.
a. New substances are formedb. It burns (light)
c. Temperature changes without adding or removing heat
d. It bubbles (makes a gas)e. It changes colorf. It forms a precipitate
Parts of Chemical
SO3(g) + H2O(l) ---> H2SO4 (aq)
Reactants Products
Yields
State of Compound
State of Compound
Real World ConnectionSO3(g) + H2O(l) ---> H2SO4 (aq)
Above is the equation for acid rainThis results from the release from industry and natural
sources into the atmosphere.The Sulfur trioxide is mixed into the atmosphere when it
rain the Sulfur trioxide mixes with rain water as it condensates from the atmosphere and falls to earth as Sulfuric acid.
Demo Lab1. Was this a chemical rxn? How Could you tell?2. If the word equation is aqueous Hydrochloric acid
and zinc metal mixes to produce Zinc chloride powder, water and Hydrogen gas. What is the symbol equation?
3. Now balance the equation.4. Would there be more H gas produced if I kept
adding HCl until the test tube was 80% full? Why or Why not.
Panther Drill
What “LAWs” tells us that equations must be balanced with = amounts on each side of the yield sign? Be specific.
Law of Conservation of Mass (Mass doesn't change)
Law of Conservation of Matter (Moles don’t change)
STOICHIOMETRY
What is stoichiometry?
• Stoichiometry is the quantitative study of reactants and products in a chemical reaction.
Panther Drill
In your own words define a ratio, and give an example.
What You Should Expect
• Given : Amount of reactants • Question: how much of products can be
formed.• Example
• 2 A + 2B 3C• Given 20.0 grams of A and sufficient B, how
many grams of C can be produced?
What do you need?
You will need to use i. molar ratios, ii. molar masses, iii. balancing and interpreting equations, andiv. conversions between grams and moles.
Note: This type of problem is often called "mass-mass."
Steps Involved in Solving Mass-Mass Stoichiometry Problems
• Balance the chemical equation correctly• Using the molar mass of the given substance,
convert the mass given to moles. • Construct a molar proportion (two molar
ratios set equal to each other) • Using the molar mass of the unknown
substance, convert the moles just calculated to mass.
Mole Ratios
A mole ratio converts moles of one compound in a balanced chemical equation into moles of another compound.
Example
Reaction between magnesium and oxygen to form magnesium oxide. ( fireworks)
2 Mg(s) + O2(g) 2 MgO(s) Mole Ratios:
2 : 1 : 2
Practice Problems
1) N2 + 3 H2 ---> 2 NH3
Write the mole ratios for N2 to H2 and NH3 to H2.
2) A can of butane lighter fluid contains 1.20 moles of butane (C4H10). Calculate the number of moles of carbon dioxide given off when this butane is burned.
Panther Drill What is the ratio between male and female
students in the picture: write all possible ratios, then write it out like a chemical equation.
class picture
Panther Drill answers
1) 17 total students, 7 females, 10 males.Males to females = 10 to 7 or 10 males
7 femaleFemales to males: 7 to 10 or 7 females
10 males Males to total: 10 : 17 10 males/17 studentsFemales to total 7 : 17 , 7 females/17studentsBal Equat: 10 males + 7 females Class
Ratios Ratios can be expressed in many ways: 3:5, 3 to 5 or 3/5We are going to be mainly concerned with ratios
displayed as fractionsThe ratio of A to B = A .
B**** The first item (number) always is the
numerator, the last is the denominator. ***
Ratios1) It takes 2 eggs ¼ onion, 12 slices of jalapenos and 1
slice of cheese to make Mr P.’s favorite omelet what are the total ratio and the ratio of each ingredient to the end(fraction form) result.
Total: 2eggs : ¼onion: 12jalapeno: 1slice: 1omelet2 eggs/1omelet ¼ onion/1 omelet12 slices jalapeno/ 1 omelet1 slice of cheese/ 1 omelet.Is this a problem a good example to use in
chemistry? Why?
Example
Panther Drill
Balance the equation and write down the ratios of each reactant to the product
_____H2 + _____O2 _____H2O
2 mol H2 : 2 mole H2O -- 1:1
1 mol O2 : 2 mole H2O
2 1 2
Panther Drill
Balance the equations and write the mole ratios of each reactant to each product (Should be 4 ratios total)
_____NH3 + _____O2 _____NO + _____H2O
NH3 /NO
NH3 / H2O
O2 /NO
O2 / H2O
Set this chart up in notebookSteps Problem 1 Problem 21
2
3
4
5
Solving Mole-Mass or Mass to Mass Problems. List these in your table next to the number
1. Identify what is given and what the problem is asking for.
2. Write and balance the chemical equation correctly. (depending on what is required)
** 1 and 2 can be in either order3. Using the molar mass of the given substance,
convert the mass given to moles (if needed)4. Construct a molar proportion equation (w/ one
or more molar ratios in conversion fraction form) 5. Convert the moles just calculated to mass
wanted by the problem.
ProblemIf you have 13 moles of oxygen and excess Aluminum,
how many grams Aluminum Oxide will be formed?
1) GIVEN:_____________
NEEDED:______________
13 mol O2
Grams Al2O3
2) Write and or balance the chemical equation correctly.
______Al + _____O2 _____ Al2O3 4 3 2
3) Using the molar mass of the given substance, convert the mass given to moles (if needed)
NOT NEEDED IN THIS PROBLEM BECAUSE YOU HAVE BEEN GIVEN MOLES, OFTEN YOU WILL
BE GIVEN MASS OF A SUBSTANCE!!!!
4) Construct a molar ratio equation (w/ one or more molar ratios in conversion fraction form) & do the math
Mole ratio = 3 moles O2 : 2 moles of Al2O3
Keeping in mind we have oxygen and need to find Al2O3 , what goes in the numerator and what goes in the denominator?
2 moles of Al2O3
3 moles of O2
13 moles of O2 X 2 moles of Al2O3
3 moles of O2
= 8.67mol Al2O3
5) Convert the moles just calculated to mass wanted by the problem (using molar mass)
Atomic masses:
Compound: Al2O3
Molar Mass = (27 x 2) + (16 x 3) =
X =
102 g per mole of Al2O3
O = 16, Al = 27
8.67mol Al2O3 102 g Al2O3
1 mole Al2O3
884.34 g Al2O3
Create a table in your notes like is on the next slide
Set this chart up in notebookSteps Problem 1 Problem 21
2
3
4
5
Solving Mole-Mass or Mass to Mass Problems. List these in your table next to the number
1. Identify what is given and what the problem is asking for.
Have: “have, will react, are consumed…”Need: “are produced, will be made, yields…”
2. Write and balance the chemical equation correctly. (depending on what is required)
Solving Mole-Mass or Mass to Mass Problems. List these in your table next to the number
3. Using the molar mass of the given substance, convert the mass given to moles (needed if you are given grams, not needed if given moles)
4. Construct a molar proportion equation (w/ one or more molar ratios in conversion fraction form)
3 mol N2 / 1 mole Mg
5. Convert the moles just calculated to mass wanted by the problem.
ProblemIf you have 13 moles of oxygen and excess Aluminum,
how many grams Aluminum Oxide will be formed?
1) GIVEN:_____________
NEEDED:______________
13 mol O2
Grams Al2O3
2) Write and or balance the chemical equation correctly.
______Al + _____O2 _____ Al2O3 4 3 2
3) Using the molar mass of the given substance, convert the mass given to moles (if needed)
NOT NEEDED IN THIS PROBLEM BECAUSE YOU HAVE BEEN GIVEN MOLES, OFTEN YOU WILL
BE GIVEN MASS OF A SUBSTANCE!!!!
4) Construct a molar ratio equation (w/ one or more molar ratios in conversion fraction form)
Mole ratio = 3 moles O2 : 2 moles of Al2O3
Keeping in mind we have oxygen and need to find Al2O3 , what goes in the numerator and what goes in the denominator?
2 moles of Al2O3
3 moles of O2
13 moles of O2 X 2 moles of Al2O3
3 moles of O2
= 8.67mol Al2O3
5) Convert the moles just calculated to mass wanted by the problem (using molar mass)
Atomic masses:
Compound: Al2O3
Molar Mass = (27 x 2) + (16 x 3) =
X =
102 g per mole of Al2O3
O = 16, Al = 27
8.67mol Al2O3 102 g Al2O3
1 mole Al2O3
884.34 g Al2O3
Column #2 Mole-Mass Problem You Try
• Problem : 1.50 mol of KClO3 decomposes. How many grams of O2 will be produced?
[k = 39, Cl = 35.5, O = 16]
2 KClO3 2 KCl + 3 O2
Steps…Get Your Correct Answer
• Is equation balanced?• What do you have, what do you need
• Use mole ratio • Get the answer in moles • Convert to grams using molar mass
REMEMBERIf you are given a mass in the
problem, you will need to convert this to moles first. Ok?
YES
1.50 mol of KClO3 grams of O2
3 mol O2 / 2 mol KClO3
O2 = 32
Mass reactant to Mass ProductsGiven the reaction __Mg3N2 + __H2O ___MgO + ___ NH3
If 125 grams of MgO is produced, how much Mg3N2 was required in the reactants. Assume you have plenty (excess) water.
What are the words that tell you what you have and what you need?
Panther Drill
Complete the handout on your desk, it is eerily similar to the one we did last Thursday/Friday!!!
A/B Partners
1. Get w/ a partner, If there is an odd # I will be a partner.
2. 1 Person do problem A, 1 Person do problem B. BY YOURSELVES!!!!!
3. When both are FINISHED. Each partner will explain their problem to the other STEP BY STEP.
4. Sign off on each others work and let me see it.
Partner A and B
For the reaction 2Na + Cl2 2NaCl, how many grams of sodium chloride can be produced from 500. g each of sodium?
For the reaction 2Na + Cl2 2NaCl, how many grams of sodium chloride can be produced from 500. g each of chlorine?
Partner A and B
For the reaction 2Na + Cl2 2NaCl, how many grams of sodium chloride can be produced from 500. g each of sodium?
For the reaction 2Na + Cl2 2NaCl, how many grams of sodium chloride can be produced from 500. g each of chlorine?
Using the unbalanced equation: __CaC2 + __H2O __C2H2 + __Ca(OH) 2.
If 15 grams of C2H2 are produced, how much water will be needed in the reactants?
1) ____ Na3PO4 + ____ KOH ____ NaOH + ____ K3PO4___________________
2) ____ MgF2 + ____ Li2CO3 ____ MgCO3 + ____ LiF___________________
3) ____ P4 + ____ O2 ____ P2O3_________________
4) ____ RbNO3 + ____ BeF2 ____ Be(NO3)2 + ____ RbF_________________
5) ____ AgNO3 + ____ Cu ____ Cu(NO3)2 + ____ Ag_________________
6) ____ CF4 + ____ Br2 ____ CBr4 + ____ F2_________________
7) ____ HCN + ____ CuSO4 ____ H2SO4 + ____ Cu(CN
Panther Drill Chem 4-14
Balance these equations____C6H12O6 + ____O2 ___CO2 + ____H2O
1 6 6 6 ___ GaBr3 + ___ Na2SO3 ___ Ga2(SO3)3 + ___ NaBr
2 3 1 6
Panther Drill 4/15What is the % of Sodium in salt?
Mass % = mass of element in 1 mole of a compound X 100molar mass of compound
% = atomic mass of sodium X 100 molar mass salt = 23 g X 100 =
58.5 g39.32 %
PracticeDetermine the % composition of the following:1. % Cl in NaCl
2. % H in C6H12O6
3. % Al in Al2O3
PracticeDetermine the % composition of the following:1. % Cl in NaCl
2. % H in C6H12O6
3. % Al in Al2O3