1. Chapter 10 Chemical Quantities
10.1 The Mole: A Measurement of Matter
10.2 Mole-Mass and Mole-Volume Relationships
10.3 Percent Composition and Chemical Formulas
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2. The Mole-Mass Relationship
Use the molar mass of an element or compound to convert between the mass of a substance and the moles of the substance.
The conversion factors for these calculations are based on the relationship
1 mole of any substance = its molar mass
molar mass
1 mol
and
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3. Converting Moles to Mass
Sample Problem 10.5
Converting Moles to Mass
What is the mass, in grams, of 9.45 mol of aluminum oxide?
Molar mass of Al2O3 = g
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4. Calculate Solve for the unknown.
Sample Problem 10.5
Calculate Solve for the unknown. 2
Multiply the given number of moles by the conversion factor.
9.45 mol Al2O3 ×
102.0 g Al2O3
1 mol Al2O3
= 964 g Al2O3
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5. Converting Mass to Moles
Sample Problem 10.6
Converting Mass to Moles
When iron is exposed to air, it corrodes to form a red-brown rust. Rust is iron(III) oxide (Fe2O3). How many moles of iron(III) oxide are contained in 92.2 g of pure Fe2O3, if molar mass of Fe2O3 is 159.6g?
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6. Calculate Solve for the unknown.
Sample Problem 10.6
Calculate Solve for the unknown. 2
Multiply the given mass by the conversion factor.
92.2 g Fe2O3 ×
1 mol Fe2O3
159.6 g Fe2O3
= mol Fe2O3
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7. The Mole-Volume Relationship
Avogadro’s Hypothesis
Avogadro’s hypothesis states that equal volumes of gases at the standard temperature and pressure contain equal numbers of particles.
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8. The Mole-Volume Relationship
Avogadro’s Hypothesis
Whether the particles are large or small, large expanses of space exist between individual particles of gas.
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9. The Mole-Volume Relationship
Avogadro’s Hypothesis
At STP, 1 mol, or 6.02 × 1023 representative particles, of any gas occupies a volume of 22.4 L.
The quantity, 22.4 L, is called the molar volume of a gas.
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10. The Mole-Volume Relationship
Calculating the Volume and Moles of a Gas at STP
The molar volume is used to convert between the number of moles of gas and the volume of the gas at STP.
The conversion factors for these calculations are based on the relationship 22.4 L = 1 mol at STP.
22.4 L
1 mol
and
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11. Calculating Gas Quantities at STP
Sample Problem 10.7
Calculating Gas Quantities at STP
Sulfur dioxide (SO2) is a gas produced by burning coal. It is an air pollutant and one of the causes of acid rain. Determine the volume, in liters, of 0.60 mol SO2 gas at STP.
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12. Calculate Solve for the unknown.
Sample Problem 10.7
Calculate Solve for the unknown. 2
Multiply the given number of moles by the conversion factor.
0.60 mol SO2 ×
22.4 L SO2
1 mol SO2
= 13 L SO2
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13. The Mole-Volume Relationship
The mole is at the center of your chemical calculations.
To convert from one unit to another, you must use the mole as an intermediate step.
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14. END OF 10.2
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