Medway High School
Name_________________
Accel Chemistry
Chapter 10 Practice Problems & Test Review
Chemical Quantities Answer Sheet
 Show all work (no work, no credit) Answers in RED
1. How many moles is 750 billion atoms H in water? (1 billion = 1x109)
H=1.25x10-12 H moles
H2O=6.25x10-13moles H2O
2. How many carbon atoms are in a 9 mole gasoline? (gasoline = C8H18)
4.32x1025 C atoms
3. What is the molar mass of Iron (III) Oxalate?
Fe2(C2O4)3 = 375.6 g/mol
4. How many moles are 500 grams Iron (III) Oxalate?
1.33 mol Fe2(C2O4)3
5. How many grams is 1.78 moles Iron (II) Hydroxide?
Fe(OH)2 = 89.8 g/mol
159.8 g Fe(OH)2
6. Calculate the volume of 3.44 moles methane, CH4, gas at STP:
77.06 liters CH4
7. What is the density of Nitrogen Dioxide at STP?
NO2 46g/mol
2.05 g/l NO2
8. What is the volume of 3.24x1022 molecules of Chlorine gas at STP?
1.21 liters Cl2
9. How many H atoms and O atoms are in a 500 ml water bottle?
H atoms = 3.33x1025
O atoms = 1.67x1025
10. A dime is an alloy (a mixture of two solids) of 75% Copper (Cu) and 25% Nickel
(Ni) and has a mass of 2.27 grams; how many Cu, Ni, and total atoms does a dime
contain?
Cu = 1.61x1022
total atoms = 2.19x1022
21
Ni = 5.80x10
Given a container with 50-ml of Ethanol (C2H6O); the density of Ethanol is 0.789g/ml
11. Ethanol’s molar mass 46 g/mol
12. Moles of ethanol
1.166 moles Ethanol
13. Carbon atoms 1.4x1024 C atoms
Mr. Hoek
1
Chapter-10 Practice Problems
February 14, 2011
Medway High School
Name_________________
Accel Chemistry
9) Calculate the % Oxygen in Magnesium Hydroxide: Mg(OH)2
a) 54.9%
b) 38.7%
c) 40%
d) none of these
10) Find the empirical formula for 27.6% O and remainder Fe:
a) FeO
b) Fe2O3
c) Fe3O4
d) none of these
11) Determine the molecular formula for 94.1% oxygen O and 5.9% hydrogen H. The
molar mass of the molecule is 51 g/mole.
a) H2O
b) H2O2
c) H3O3
d) none of these
 Problems
Solve the following problems Show all units & work for each step, no work no credit!
Given a container with 250-ml of Ethanol (C2H6O); answer the following questions:
(Assume that the Ethanol is pure and the density of Ethanol is 0.789g/ml)
12) Ethanol’s molar mass 46 g/mol 13) Moles of ethanol 5.83 moles
14) Carbon atoms 7.00x1024
A gas has a composition of 42.86% carbon and the remainder oxygen give its empirical
formula, its name, and calculate its density. If a balloon filled with 44.8 liters of the gas,
at STP how many oxygen atoms are in the balloon.
15) Empirical formula______CO________ 16) Name of the gas Carbon Monoxide
17) Density of the gas _____1.25 g/l_____18) Oxygen atoms _______1.2x1024______
How many Carbon Dioxide molecules and oxygen atoms are in a 75.0-gram sample of
Carbon Dioxide gas? Assume that the container is at STP,
19) Carbon Dioxide molecules 1.02x1024 20) Oxygen atoms 2.04x1024
21) Density of Carbon Dioxide ____1.96 g/liter__________
Mr. Hoek
2
Chapter-10 Practice Problems
February 14, 2011