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Chemical Composition

Stoichiometry Review

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a. 3.01 molb. 1.81 1047 molc. 1.00 mold. 0.500 mole. 3.01 1023 mol

6.1 How many moles of Ca are 3.01 1023 atoms of calcium?

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a. 1.000 gb. 6.022 1023 gc. 0.01791 g d. 26.00 ge. 55.85 g

6.3 How many grams are in 1.000 mol of iron?

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a. 112.12 g/molb. 80.05 g/molc. 66.04 g/mold. 114.00 g/mole. 95.23 g/mol

6.4 What is the molar mass of ammonium nitrate?

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a. 4.55 gb. 4.31 1045 gc. 1.18 10–2 g d. 6.02 1023 ge. 48.0 g

6.6 What is the mass of 4.55 1023 copper atoms?

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a. 3.730 10–2 molb. 2.268 10–3 molc. 2.268 103 mold. 5.672 10–3 mole. 1.418 10–2 mol

6.7 How many moles are in 5.672 g of iron(III) sulfate?

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a. 0.27 molb. 0.20 molc. 0.16 mold. 0.56 mole. 2.0 102 mol

6.9 How many moles are in 5.6 g of lithium nitride?

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a. 6.90 mol Ob. 3.45 mol Oc. 5.75 mol Od. 13.5 mol Oe. 17.3 mol O

6.11 How many moles of oxygen are in 3.45 mol of diphosphorus pentoxide?

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a. 90.70 g b. 0.1765 gc. 5.66 g d. 181.4 ge. 0.353 g

6.14 What is the mass of 5.660 mol of dinitrogen tetrahydride?

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a. CH1.5O and C2H3O2

b. C3H5O3 and C6H10O6 c. C4H6O4 and C8H12O8

d. C4H6O4 and C2H3O2

e. C2H3O2 and C4H6O4

6.19 An unknown compound has a molar mass of 118.10 g/mol. Given the following mass percent composition, calculate the empirical and molecular formulas: 40.7% C, 5.13% H, and 54.2% O.

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a. C6H8O6

b. C4H4O4 c. C3H4O3 d. CHOe. CH2O

6.22 What is the empirical formula of ascorbic acid, C6H8O6, a compound found in citrus fruits?

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a. H2 b. N2 c. O2 d. F2

e. Cl2

6.23 Identify the diatomic molecule that has a mass of 33.86 g and contains 0.891 moles of molecules.

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a. Cr2O7

b. Cr2O4

c. CrOd. CrO1.5

e. Cr2O3

6.24 Calculate the empirical formula of a 5.85 g sample of an unknown chromium oxide containing 4.00 g of chromium.

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a. CH b. CH2

c. C2Hd. C2H3

e. CH3

6.25 What is the empirical formula of a compound that contains 14.5% hydrogen and 85.5% carbon by mass?

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a. 6.25%b. 26.08%c. 54%d. 52.12%e. 64.32%

6.26 What is the mass percentage of oxygen in glycerol, C3H8O3?

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a. CH2Ob. C3H6O3

c. C6H12O6

d. C2H4O2

e. None of the above

6.27 The empirical formula of a compound is found to be CH2O. If its molar mass is 180.2 g/mol, what is the molecular formula of the compound?

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a. 7.86 gb. 5.35 gc. 7.863 gd. 0.1624 ge. None of the above

6.28 A variety of Freon contains 69.58% chlorine by mass. How many grams of chlorine are contained in 11.3 g of this substance?

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a. 6.527%b. 13.06%c. 19.60%d. 39.17%e. None of the above

6.29 What is the mass percentage of oxygen in potassium chlorate?

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a. C9H8O4

b. C3H2Oc. C2H2O2

d. C2H2Oe. None of the above

6.30 A compound is found to contain 60.00% C, 4.48% H and 35.53% O. What is its empirical formula?