Chapter 4: Calculations and the Chemical Equation
1. What is the mass of 4.00 moles of helium, the gas commonly used to fill party balloons
and lighter-than-air ships?
A) 4 amu
B) 4.00 g
C) 8.00 g
D) 16.0 g
E) 2.41 × 1024 g
2. Which notation properly indicates how two molecules of diatomic oxygen would be
represented in a chemical equation?
A) (O2)2
B) O4
C) 2O2
D) O2O2
E) Any of the above notations can be used.
3. How many molecules of water are present in a 5.65 mole sample of water?
A) 4.00 × 1024 molecules
B) 1.07 × 1023 molecules
C) 3.40 × 1024 molecules
D) 9.39 × 10−24 molecules
E) 4.00 × 1025 molecules
4. Consider the two beakers labeled A and B. Beaker A contains 1 mole of iron atoms,
and Beaker B contains 1 mole of lead atoms. Which statement concerning these
samples is known with certainty?
A) Beakers A and B contain an equal number of atoms.
B) Beakers A and B contain equal masses of atoms.
C) Beakers A and B contain an equal volume of atoms.
D) Beakers A and B contain samples with the same density.
E) None of the above is known with certainty.
5. The chemical equation below is not balanced. Balance the equation, then determine
which statement concerning the balanced equation is true.
KClO3(s)  KCl(s) + O2(g)
A) The balanced equation will have an equal number of moles of reactants and products.
B) The balanced equation will have three atoms of oxygen on each side.
C) The balanced equation will have one atom of potassium on each side.
D) The balanced equation will have two atoms of chlorine on each side.
E) The balanced equation will contain a substance whose coefficient is 1.
6. Hydrogen fluoride will react with glass (silicon dioxide, SiO2) according to the equation
below. What mass of HF is required to react completely with 16.0 g of glass? [Molar
masses: Si, 28.09 g/mol; F, 19.00 g/mol; H, 1.01 g/mol; O, 16.00 g/mol]
4HF(g) + SiO2(s)  SiF4(g) + 2H2O(g)
A) 5.33 g
B) 21.3 g
C) 64.0 g
D) 80.0 g
E) 320 g
7. A sample of sulfur contains 1.81  1024 atoms of sulfur. How many moles of sulfur
does this represent?
A) 1.81 mol B) 3.01 mol C) 0.333 mol D) 1.09 mol E) 1.77 mol
8. Lithium oxide can be produced by the reaction shown below. If a manufacturing
company wants to make 25.0 g of Li2O, what mass of Li is necessary? [Molar masses:
Li, 6.94 g/mol; O, 16.00 g/mol]
4Li(s) + O2(g)  2Li2O(s)
A) 0.0861 g Li
D) 12.5 g Li
B) 2.903 g Li
E) 23.2 g Li
C) 11.6 g Li
9. What mass of sodium hydroxide is necessary to react with a solution containing 73.00 g
HCl, according to the chemical equation below? [Molar masses: NaOH, 39.99 g/mol;
HCl, 36.45 g/mol]
NaOH(aq) + HCl(aq)  NaCl(aq) + H2O(l)
A) 80.09 g B) 66.54 g C) 39.99 g D) 1.850 g E) 7.445 g
10. Iron reacts with oxygen to form iron(III) oxide according to the chemical equation
below. What is the theoretical yield of product when 5.00 grams of Fe react with excess
O2? [Molar masses: Fe, 55.85 g/mol; O, 16.00g/mol]
4Fe(s) + 3O2(g)  2Fe2O3(s)
A) 13.1 g B) 6.53 g C) 7.15 g D) 2.50 g E) 70.5 g
11. What is the mass of 3.01 mol of sulfur atoms?
A) 1.81  1024 g B) 32.06 g C) 3.01 g D) 0.150 g E) 96.5 g
12. How many atoms of sulfur are present in a 155 g sample of sulfur? [Molar mass: S,
32.06 g/mol]
A) 2.91  1024 atoms
D) 2.91  1023 atoms
B) 6.02  1023 atoms
E) 2.01  1023 atoms
C) 3.01  1023 atoms
13. How many iron atoms are present in 0.552 mol of iron?
A) 2.798  1024 B) 6.02  1023 C) 27.98 D) 3.32  1023
E) 55.85
14. What is the formula mass of carbon dioxide? [Atomic masses: C, 12.01 amu; O, 16.00
amu]
A) 28.01 amu B) 28.01 g C) 44.01 amu D) 44.01 g E) 44.01 mol
15. Which of the choices is the correctly balanced form of the following equation?
C6H14(l) + O2(g)  CO2(g) + H2O(l)
A) C6H14(l) + 13O2(g)  6CO2(g) + 7H2O(l)
B) C6H14(l) + 19O(g)  6CO2(g) + 7H2O(l)
C) C6H14(l) + 19O2(g)  6CO2(g) + 7H2O(l)
D) 2C6H14(l) + 19O2(g)  12CO2(g) + 14H2O(l)
E) C12H28(l) + 38O(g)  12CO2(g) + 14H2O(l)
16. How many moles of hydrogen gas are needed to react with oxygen to form one mole of
water?
2H2(g) + O2(g)  2H2O(l)
A) 0.5 mol B) 1 mol C) 2 mol D) 4 mol E) 6 mol
17. Methanol (CH3OH) is the fuel used by race cars in the Indianapolis 500. It burns in the
engine according to the equation below. How many moles of oxygen gas are necessary
to react completely with 425 moles of methanol?
2CH3OH(l) + 3O2(g)  2CO2(g) + 4H2O(g)
A) 3 mol
B) 255 mol
C) 283 mol
D) 638 mol
E) 1275 mol
18. Choose the best classification of the reaction represented by the following equation:
2KClO3(s)  2KCl(s) + 3O2(g)
A) decomposition
D) double-replacement
B) combination
E) None of the choices are correct.
C) single-replacement
19. Choose the best classification of the reaction represented by the following equation:
MgO(s) + CO2(g)  MgCO3(s)
A) single-replacement
D) decomposition
B) double-replacement
E) precipitation
C) combination
20. Choose the best classification of the reaction represented by the following equation:
CuSO4·5H2O(s)  CuSO4(s) + 5H2O(l)
A) single-replacement
D) decomposition
B) double-replacement
E) oxidation–reduction
C) combination
21. Choose the best classification of the reaction represented by the following equation:
Zn(s) + CuSO4(aq)  ZnSO4(aq) + Cu(s)
A) single-replacement
D) decomposition
B) double-replacement
E) acid–base
C) combination
22. Choose the best classification of the reaction represented by the following equation:
BaCl2(aq) + K2SO4(aq)  BaSO4(s) + 2KCl(aq)
A) single-replacement
D) decomposition
B) double-replacement
E) oxidation–reduction
C) combination
23. What is the mass of 4.35 moles of aluminum?
A) 0.163 g B) 117 g C) 2.62  1024 g D) 9.78  1022 g E) 27.8 g
24. Calculate the number of moles of BaF2 in a 10.0 g sample of BaF2.
A) 9.77 mol B) 0.115 mol C) 17.4 mol D) 0.0631 mol E) 0.0570 mol
25. What is the mass of 3.5  1022 molecules of CO2?
A) 5.9  10–2 g B) 2.6 g C) 1.8  1024 g D) 1.5  10–3 g E) 3.9 g