Moles are a Chemist Best FriendChapter 10

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Objectives: Moles are a Chemist Best Friend• I can identify what a mole is in chemistry.

• I can convert between moles and representative particles of substances.

• I can convert between moles and mass of substances.

• I can calculate the percentage composition of substances.

Measuring MatterWhat are three ways we can measure matter? 1.

2.

3.

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Measuring Apples

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Grouping Matter• Easy way to measure all matter. r500

Dozen dougnuts= 12

Gross of pencils= 144

Ream of paper = 500 Byte of information storage= 4 bits

Grouping Matter• How do scientists’ group the representative

particles that make-up matter?

Representative particles: substances that make-up matter.

Examples: • Atoms• Ionic Compounds• Molecules (covalent cmpds.)

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Classification of Matter

Grouping Representative Particles

1 mole = 6.02x1023 representative particles (Avogadro’s Number)

• “The Mole is a Unit Song” (nclark.net)

A mole is used to group representative particles.

Mole Map

number ofrepresentative

particles

mass

1 mol22.4L

22.4L1 mol

6.02 x 10 particles1 mol

23

6.02 x 10 particles231 mol

1 molmolar mass

molar mass1 mol

moles

volumeat STP

Converting Moles to Representative ParticlesEx. Propane (C3H8) is a gas used for cooking and

heating. How many molecules of propane is equal to 2.4 moles of propane?

Convesion: Representative Particles to Moles Ex. Magnesium is a light metal used in the

manufacture of aircraft and automobile wheels. How many moles of magnesium equals 1.25x1023

atoms of magnesium?

Mole Map

number ofrepresentative

particles

mass

1 mol22.4L

22.4L1 mol

6.02 x 10 particles1 mol

23

6.02 x 10 particles231 mol

1 molmolar mass

molar mass1 mol

moles

volumeat STP

Bell Ringer: Moles1. Define and give two examples of a representative

particle.2. a. What is a mole? b. How many atoms are in a mole of Cu?

3. How many moles are in 4.65x1024 molecules of CO2 ?

Conversions: Mole-Representative Particles

(Homework Problems Key)

1. 1.2x1024 molecules (2sig. Figs)2. 9.0x1023 molecules (2 sig figs)3. 4.5x1023 molecules (2 sig figs)4. 9.0x1024 molecules (2 sig figs)5. 2.1x1023 molecules (2 sig figs)1. 1.00 moles (3 sig figs)2. 2.00 moles (3 sig figs)3. 2.5x10-4 moles (2 sig figs)4. 5.6x102 moles (2 sig figs)5. 1.2x10-4 moles (2 sig figs)

Conversion: Mole-Representative Particles Homework Problems

Converting Moles to Mass• How do we convert from moles to mass?

Objectives: Moles are a Chemist Best Friend• I can identify what a mole is in chemistry.

• I can convert between moles and representative particles of substances.

• I can convert between moles and mass of substances.

• I can calculate the percentage composition of substances.

Mole-Mass Conversion

Mole Map

number ofrepresentative

particles

mass

1 mol22.4L

22.4L1 mol

6.02 x 10 particles1 mol

23

6.02 x 10 particles231 mol

1 molmolar mass

molar mass1 mol

moles

volumeat STP

Converting Moles to Mass• How do we convert from the moles of a

substance to the mass of a substance?

Conversion: Moles- Mass• Mole-Mass Conversion: 1 mole of a substance = molar mass of the substance

• Molar mass = substance’s atomic mass in grams

Molar Mass of an Element• Molar mass = element’s atomic mass(grams)• Round atomic mass to tenths place.

Ex. A mole of sulfur has a molar mass of?

Ex. A mole of sodium has a molar mass of?

Molar Mass of a Compound• Molar mass = sum of the elements’ atomic masses

in the compound • Need chemical formula to calculate the molar

mass of a compound.Ex. A mole of NaCl has a molar mass of?

Ex. A mole of H2O has a molar mass of?

Bell Ringer: Chemistry1. What is the representative particle for each substance

below? (atom, ionic compound, or molecule)

a. Na2O b. Fe c. H2 d. Ne

2. How many atoms are in 2.5 moles of copper?

3. a. What is the molar mass of silver, Ag?

b. What is the molar mass of Al2(CO3)3?

Mole Packet Questions

Mole-Mass Conversions• 1 mole = molar mass of substanceEx. When iron is exposed to air, it corrodes to form

red-brown rust. How many moles of iron (III) oxide are contained in 92.2g of pure Fe2O3?

Mole Map

number ofrepresentative

particles

mass

1 mol22.4L

22.4L1 mol

6.02 x 10 particles1 mol

23

6.02 x 10 particles231 mol

1 molmolar mass

molar mass1 mol

moles

volumeat STP

Mole-Mass ConversionsEx. What is the mass of 9.45 moles of aluminum

oxide? (1 mole = molar mass of a substance)

Mole Map

number ofrepresentative

particles

mass

1 mol22.4L

22.4L1 mol

6.02 x 10 particles1 mol

23

6.02 x 10 particles231 mol

1 molmolar mass

molar mass1 mol

moles

volumeat STP

Mole Conversions

Mole to Particle Conversion:1 mole = 6.02x1023 particles (atoms or cmpds)

Mole to Mass Conversion:1 mole = molar mass of the substance (grams)

Mole Map

number ofrepresentative

particles

mass

1 mol22.4L

22.4L1 mol

6.02 x 10 particles1 mol

23

6.02 x 10 particles231 mol

1 molmolar mass

molar mass1 mol

moles

volumeat STP

Bubble Gum Lab

• Purpose: Practice mole conversions and calculate the % composition of sugar in bubble gum.

Mole Map

number ofrepresentative

particles

mass

1 mol22.4L

22.4L1 mol

6.02 x 10 particles1 mol

23

6.02 x 10 particles231 mol

1 molmolar mass

molar mass1 mol

moles

volumeat STP

Chemical Quantities Objectives (Chpt.10)• I can identify what a mole is in chemistry.

• I can convert between moles and representative particles of substances.

• I can convert between moles and mass of substances.

• I can calculate the percentage composition of substances.

Bell Ringer: Mole Conversions1. Define “mole”. 2. Name the representative particle of each

substance. (atom, molecule, ionic compound)a. oxygen gas b. sodium sulfidec. potassium d. sulfur dioxide3. What is the molar mass of a substance?4. What is the conversion needed for each problem below?a. mole to representative particle conversion?b. mole to mass conversion?

Chemical Quantities Quiz Questions

Fun with Moles Review

Purpose: Work together in groups to competitively review mole conversion calculations learned before spring break.

Moles Conversion Review Worksheet1. 0.407 moles2. 1.8x1024 atoms3. a. 40.3g b. 74g c. 78g d.96 g4. 0.0417 mole AgCl5. 0.35 mole Cu(OH)2

6. 0.258 mol SiO2

7. 51 gH2O2

8. 120 g9. 1,040 g C5H12

10. 52.7 g Cu

Mole Map

number ofrepresentative

particles

mass

1 mol22.4L

22.4L1 mol

6.02 x 10 particles1 mol

23

6.02 x 10 particles231 mol

1 molmolar mass

molar mass1 mol

moles

volumeat STP

Mole Conversions: 2 step problems1. How many molecules are there in 100 grams of CCl4 ?

2. How many grams do 1.2x1021 molecules of BCl3 weigh?

Mole Conversions: 2 step Problems

Mole Conversion LabProblem: How many molecules are present in a

tablespoon of the following substances?a. sodium chlorideb.waterc. calcium carbonate

Design and conduct an experiment that will help you solve this problem. Make sure to include a hypothesis, data section, and conclusion.

Mole Conversion Lab Questions

Mole Map

number ofrepresentative

particles

mass

1 mol22.4L

22.4L1 mol

6.02 x 10 particles1 mol

23

6.02 x 10 particles231 mol

1 molmolar mass

molar mass1 mol

moles

volumeat STP

Percentage Composition of a Compound

• Percent of mass each element contributes to the compound’s molar mass.

• How do we calculate % composition of a compound?

% Composition from Chemical Formula

% mass of element =

Ex. Propane, C3H8 is one of the compounds obtained from petroleum and is used to fuel homes and gas grills. Calculate the percent composition of propane.

% Composition of Compound• What is the % composition of each element in

the following compound, Al(NO2)3 ?

Mole Conversions: 2 step Problems

% Composition as a Conversion Factor• Use % composition data to calculate the mass of an

element in a specific sample of that compound.

• Ex. What is the mass of Al in 6.5 g of Al(NO2)3 ?

% Composition as a Conversion Factor

• What is the mass of Al in 6.5 g of Al(NO2)3 ?

% Composition as a Conversion Factor

• What is the mass of N in 6.5 g of Al(NO2)3 ?

• What is the mass of O in 6.5 g of Al(NO2)3?

Bell Ringer: Chemical Quantities1. How many grams are in 5.0 moles of Cs3N ?

2.How many moles are in 3.7x1021 cmpds. of NaCl?

3. What is the % composition of Cu2(SO4)?

4. How many grams of Cu are in 9.8 g of Cu2(SO4)?

Hydrate Lab

•Hydrate: Cu(SO4) . H2O

• Anhydrous salt: Cu(SO4)

Mole Map

number ofrepresentative

particles

mass

1 mol22.4L

22.4L1 mol

6.02 x 10 particles1 mol

23

6.02 x 10 particles231 mol

1 molmolar mass

molar mass1 mol

moles

volumeat STP