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Date
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General Chemistry – Unit 11 Review
Molar volume and gas stoichiometry
1. A mixture contains 8.00 g each of O2, CO2, and SO2 at STP. Calculate the volume
of this mixture. Which of the gases would exert the greatest pressure and why?
22.4L
Molar volume =
1mole
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2. Nitrogen gas and hydrogen gas combine to produce ammonia gas (NH3). What
volume of hydrogen gas at STP would be required to react with 10.0 g of nitrogen
gas?
3. Consider the following reaction: P4(s) + 6 H2(g)  4 PH3(g)
What volume of hydrogen gas at 25C and 0.981 atm is required to react completely
with 2.51 g of P4 ?
L  atm
PV  nRT
R  0.0821
mole  K
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Modeling Chemistry
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U11 gen review v.pp
4. A 550 mL flask of hydrogen gas is collected at 769 mm and 35˚C by displacement of
water from the flask. The vapor pressure of water at 35˚C is 42.2 mmHg. How
many moles of hydrogen gas are in the flask?
Molar concentration, molar volume stoichiometry
5. What mass of sodium carbonate, Na2CO3, is needed to prepare 1.25 L of a 0.75M
solution? Draw a particle diagram to represent the dissociation of sodium
carbonate in water.
6. How many moles of lead(II) hydroxide (solid) can be formed when 0.0500L of 0.125
M Pb(NO3)2 solution reacts with excess sodium hydroxide?
7. Cobalt (II) nitrate (aq) reacts with sodium hydroxide (aq) to form solid cobalt (II)
hydroxide and aqueous sodium nitrate. If 300. mL of 1.25 M cobalt (II) nitrate
reacts with 375 mL of 1.55 M sodium hydroxide, how many grams of the precipitate
are formed?
Modeling Chemistry
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U11 gen review v.pp
8. Aqueous potassium chromate reacts with a solution of silver nitrate forming
aqueous potassium nitrate and a solid silver chromate. If 0.0120 g of silver
chromate is formed, what volume of a 0.50 M silver nitrate solution reacted?
Mass stoichiometry
9. When potassium carbonate reacts with hydrogen chloride, the products are
potassium chloride, carbon dioxide and water. What mass of hydrogen chloride is
needed to completely react with 14.8 g of potassium carbonate?
Representing reactions
10. Nitric oxide (NO) reacts with oxygen gas to produce nitrogen dioxide. In the box at
left represent a mixture containing 8 molecules of NO and 6 molecules of O2. In the
box at right represent the system after the reaction had gone to completion. Be
sure to provide a key.
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a. Write the balanced equation for the reaction.
b. Which is the limiting reactant?
c. How many molecules of the excess reactant remain?
Modeling Chemistry
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U11 gen review v.pp
11. How much heat should be transferred when 75.0 g of liquid bromine reacts with
excess hydrogen gas to form hydrogen bromide? Is the heat being transferred from
the system to the surroundings or from the surroundings to the system? Is this an
exothermic or endothermic process?
H2 + Br2 ( 2 HBr
∆Hº = 72.80 kJ
12. How much heat will be released if 25.0 g of octane (C8H18) is burned in excess
oxygen? Draw the energy bar diagram to represent this process.
C8H18 + 12 ½ O2  8 CO2 + 9 H2O
Reactants
Eth Eph Ech
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Modeling Chemistry
System
∆H = –5483.4 kJ
Activated Complex
Eth Eph Ech
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4
System
Products
Eth Eph Ech
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U11 gen review v.pp