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Chapter 6 Chapter 6

Chemical QuantitiesChemical Quantities

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How you measure how much?How you measure how much? You can measure mass, You can measure mass, or volume,or volume, or you can count pieces.or you can count pieces. We measure mass in grams.We measure mass in grams. We measure volume in liters.We measure volume in liters.

We count pieces in We count pieces in MOLES.MOLES.

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MolesMoles Defined as the number of carbon Defined as the number of carbon

atoms in exactly 12 grams of carbon-atoms in exactly 12 grams of carbon-12.12.

1 mole is 6.02 x 101 mole is 6.02 x 102323 particles. particles. Treat it like a very large dozenTreat it like a very large dozen 6.02 x 106.02 x 102323 is called Avogadro’s is called Avogadro’s

number.number.

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Representative particlesRepresentative particles The smallest pieces of a substance.The smallest pieces of a substance. For a molecular compound it is a For a molecular compound it is a

molecule.molecule. For an ionic compound it is a For an ionic compound it is a

formula unit.formula unit. For an element it is an atom.For an element it is an atom.

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Types of questionsTypes of questions How many oxygen atoms in the How many oxygen atoms in the

following?following?

–CaCOCaCO33

–AlAl22(SO(SO44))33 How many ions in the following?How many ions in the following?

–CaClCaCl22–NaOHNaOH

–AlAl22(SO(SO44))33

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Types of questionsTypes of questions How many molecules of COHow many molecules of CO22 are the in are the in

4.56 moles of CO4.56 moles of CO22 ? ?

How many moles of water is 5.87 x 10How many moles of water is 5.87 x 102222 molecules?molecules?

How many atoms of carbon are there in How many atoms of carbon are there in 1.23 moles of C1.23 moles of C66HH1212OO66 ? ?

How many moles is 7.78 x 10How many moles is 7.78 x 102424 formula formula units of MgClunits of MgCl22??

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Measuring MolesMeasuring Moles Remember relative atomic mass?Remember relative atomic mass? The amu was one twelfth the mass The amu was one twelfth the mass

of a carbon 12 atom.of a carbon 12 atom. Since the mole is the number of Since the mole is the number of

atoms in 12 grams of carbon-12,atoms in 12 grams of carbon-12, the decimal number on the periodic the decimal number on the periodic

table is also the mass of 1 mole of table is also the mass of 1 mole of those atoms in grams.those atoms in grams.

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Gram Atomic MassGram Atomic Mass The mass of 1 mole of an element in The mass of 1 mole of an element in

grams.grams. 12.01 grams of carbon has the same 12.01 grams of carbon has the same

number of pieces as 1.008 grams of number of pieces as 1.008 grams of hydrogen and 55.85 grams of iron.hydrogen and 55.85 grams of iron.

We can write this as We can write this as 12.01 g C = 1 mole 12.01 g C = 1 mole

We can count things by weighing We can count things by weighing them.them.

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ExamplesExamples How much would 2.34 moles of How much would 2.34 moles of

carbon weigh?carbon weigh? How many moles of magnesium in How many moles of magnesium in

24.31 g of Mg?24.31 g of Mg? How many atoms of lithium in 1.00 g How many atoms of lithium in 1.00 g

of Li?of Li? How much would 3.45 x 10How much would 3.45 x 102222 atoms atoms

of U weigh?of U weigh?

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What about compounds?What about compounds? in 1 mole of Hin 1 mole of H22O molecules there are two O molecules there are two

moles of H atoms and 1 mole of O atomsmoles of H atoms and 1 mole of O atoms To find the mass of one mole of a To find the mass of one mole of a

compound compound – determine the moles of the elements determine the moles of the elements

they havethey have– Find out how much they would weighFind out how much they would weigh– add them upadd them up

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What about compounds?What about compounds? What is the mass of one mole of CHWhat is the mass of one mole of CH44??

1 mole of C = 12.01 g1 mole of C = 12.01 g 4 mole of H x 1.01 g = 4.04g4 mole of H x 1.01 g = 4.04g 1 mole CH1 mole CH44 = 12.01 + 4.04 = 16.05g = 12.01 + 4.04 = 16.05g

The The molecular mass molecular mass of CHof CH44 is 16.05g is 16.05g The mass of one mole of a molecular The mass of one mole of a molecular

compound.compound.

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Gram Formula MassGram Formula Mass The mass of one mole of a compound.The mass of one mole of a compound. Calculated the same way.Calculated the same way. What is the GFM of FeWhat is the GFM of Fe22OO33??

2 moles of Fe x 55.85 g = 111.70 g2 moles of Fe x 55.85 g = 111.70 g 3 moles of O x 16.00 g = 48.00 g3 moles of O x 16.00 g = 48.00 g The GFM = 111.70 g + 48.00 g = 159.70gThe GFM = 111.70 g + 48.00 g = 159.70g

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Molar MassMolar Mass The generic term for the mass of one The generic term for the mass of one

mole. mole. The same as molecular mass, gram The same as molecular mass, gram

formula mass, and gram atomic formula mass, and gram atomic mass.mass.

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ExamplesExamples Calculate the molar mass of the Calculate the molar mass of the

following and tell me what type it is.following and tell me what type it is. NaNa22SS

NN22OO44

CC

Ca(NOCa(NO33))22

CC66HH1212OO66

(NH(NH44))33POPO44

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Using Molar MassUsing Molar Mass

Finding moles of compoundsFinding moles of compounds

Counting pieces by weighingCounting pieces by weighing

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Molar MassMolar Mass The number of grams of 1 mole of The number of grams of 1 mole of

atoms, ions, or molecules.atoms, ions, or molecules. We can make conversion factors We can make conversion factors

from these.from these. To change grams of a compound to To change grams of a compound to

moles of a compound.moles of a compound.

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For exampleFor example

How many moles is 5.69 g of NaOH?How many moles is 5.69 g of NaOH?

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For exampleFor example

How many moles is 5.69 g of NaOH?How many moles is 5.69 g of NaOH?

5 69. g

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For exampleFor example

How many moles is 5.69 g of NaOH?How many moles is 5.69 g of NaOH?

5 69. g mole

g

need to change grams to moles

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For exampleFor example

How many moles is 5.69 g of NaOH?How many moles is 5.69 g of NaOH?

5 69. g mole

g

need to change grams to moles for NaOH

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For exampleFor example

How many moles is 5.69 g of NaOH?How many moles is 5.69 g of NaOH?

5 69. g mole

g

need to change grams to moles for NaOH 1mole Na = 22.99g 1 mol O = 16.00 g

1 mole of H = 1.01 g

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For exampleFor example

How many moles is 5.69 g of NaOH?How many moles is 5.69 g of NaOH?

5 69. g mole

g

need to change grams to moles for NaOH 1mole Na = 22.99g 1 mol O = 16.00 g

1 mole of H = 1.01 g 1 mole NaOH = 40.00 g

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For exampleFor example

How many moles is 5.69 g of NaOH?How many moles is 5.69 g of NaOH?

5 69. g 1 mole

40.00 g

need to change grams to moles for NaOH 1mole Na = 22.99g 1 mol O = 16.00 g

1 mole of H = 1.01 g 1 mole NaOH = 40.00 g

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For exampleFor example

How many moles is 5.69 g of NaOH?How many moles is 5.69 g of NaOH?

5 69. g 1 mole

40.00 = 0.142 mol NaOH

g

need to change grams to moles for NaOH 1mole Na = 22.99g 1 mol O = 16.00 g

1 mole of H = 1.01 g 1 mole NaOH = 40.00 g

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ExamplesExamples How many moles is 4.56 g of COHow many moles is 4.56 g of CO22 ? ?

How many grams is 9.87 moles of How many grams is 9.87 moles of HH22O?O?

How many molecules in 6.8 g of How many molecules in 6.8 g of CHCH44??

49 molecules of C49 molecules of C66HH1212OO66 weighs how weighs how

much?much?