1. Created by C. Ippolito June 2007
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: A Measurement of Matter
Objectives
Describe methods of measuring the amount of something
Define Avogadro’s number as it relates to a mole of a substance
Distinguish between the atomic mass of an elements and its molar mass
Describe how the mass of a mole of a compound is calculated
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3. Created by C. Ippolito June 2007
Measuring Matter
Three ways to measure amount:
By Count
use units that stand for a specific number of items
dozen = 12
pair = 2
By Mass
units that stand for the weight or mass
kilogram
pound
By Volume
use units that describe the space occupied
quart
liter
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4. Created by C. Ippolito June 2007
What is a mole?
Mole
unit that measures a specific number of representative particles (atoms, molecules, formula units)
6.02 x 1023 – Avogadro’s number
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5. Converting Particles to Moles
1 mole = 6.02 x 1023 particles
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6. Converting Moles to Particles
1 mole = 6.02 x 1023 particles
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7. The Mass of a Mole of an Element
Molar Mass
the atomic mass of an element expressed in grams is the mass of a mole of the element
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8. The Mass of a Mole of a Compound
To calculate the molar mass of a compound, find the number of grams of each element in one mole of the compound. Then add the masses of the elements in the compound.
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9. Mole-Mass and Mole-Volume Relationships
Objectives
Describe how to convert the mass of a substance to the number of moles of a substance, and moles to mass
Identify the volume of a quantity of gas at STP
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10. Mole-Mass Relationship
Use the molar mass of an element to convert between the mass of a substance and the moles of a substance
to convert moles to mass:
to convert mass to moles:
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11. Mole-Volume Relationship
Avogadro’s Hypothesis
equal volumes of gases at the same temperature and pressure contain equal number of particles
Standard Temperature and Pressure (STP)
0°C (273K) and 1 atmosphere (101.3 kPa)
At STP, 1 mole (6.02 x 1023 particles) of any gas occupies 22.4 L.
Molar Volume
space (22.4 L) occupied by 1 mole of ANY gas at STP
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12. Calculating Volume at STP
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13. Calculate Molar Mass from Density
molar mass = density at STP x molar volume
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14. Percent Composition and Chemical Formulas
Objectives
Describe how to calculate the percent by mass of an element in a compound
Interpret an empirical formula
Distinguish between empirical and molecular formulas
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15. Percent Composition Compounds
the relative amounts of elements in a compound
Percent by Mass of an element in a compound is the number of grams of the element divided by the mass in grams of the compound, multiplied by 100%
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16. Calculate % Comp from Mass Data
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17. Calculate % Comp from Formula
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18. Created by C. Ippolito June 2007
Empirical Formula
Shows the smallest whole-number ratio of atoms in a compound
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19. Empirical Formula (con’t)
Shows the smallest whole-number ratio of atoms in a compound
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20. Created by C. Ippolito June 2007
Molecular Formulas
can be the same as the experimentally determined empirical formula or it is a simple whole-number multiple of the empirical formula
it is the ratio of atoms in an ACTUAL molecule
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21. Finding Molecular Formula
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