Houston Community College
Dr. Mohamed Elbaccouch
CHEM 1405
Spring 2015 - Test # 2
Answer the Following Questions.
Student Name: ______________________________
1. What is the molecular formula of H2SO4?
a. 98.09 g/mole
b. 6.02x1023 molecules
c. 54.09 g/mole
d. None of the above.
2. Write a balanced equation for the combination reaction between Nickel metal and oxygen at high
temperature to produce nickel (II) oxide.
a. 2Ni (s) + O2 (g) ---> Ni2O2 (s)
b. 2Ni (s) + O2 (g) ---> 2NiO (s)
a. 4Ni (s) + O2 (g) ---> 2Ni2O (s)
a. 2Ni (s) + O2 (g) ---> NiO (s)
3. What are the coefficients of the reactants and products when the following reaction is correctly
balanced (“1” is used here just for the purpose of filling the blank when one mole is used)?
___ Fe2O3 (s) + ___ H2 (g) ---> ___ Fe (s) + ___ H2O (g)
a. 1, 3, 2, 3
b. 2, 3, 1, 3
c. 2, 6, 4, 6
d. 2, 6, 2, 3
4. Which of the following reactions is a decomposition reaction?
a. Pb(NO3)2 (aq) + 2 KI (aq) ---> 2 KNO3 (aq) + PbI2 (s)
b. 4 Al (s) + 3 O2 (g) ---> 2 Al2O3 (s)
c. 2 NaHCO3 (s) ---> Na2CO3 (s) + H2O (g) + CO2 (g)
d. Mg (s) + Fe(NO3)2 (aq) ---> Fe (s) + Mg(NO3)2 (aq)
5. How many molecules are there in 1 mole H2?
a. 6.02 x 1023 molecules?
b. 12.0 x 1023 molecules?
a. 2.02 molecules
a. 1 molecule
6. A green balloon containing 1 mole of He at STP and a blue balloon contains 1 mole O2 at STP. Which
of the following is true?
a. Green balloon has more volume than the blue balloon at STP.
b. Green balloon has less volume than the blue balloon at STP.
c. Volume of green balloon = volume of blue balloon at STP.
d. Volume is not a function of this problem.
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7. CO is burned with excess O2 to produce CO2. Which compound is the limiting reactant?
a. CO
b. O2
c. CO2
d. O
8. Convert 100 psi to atm (use this conversion factor 1 atm = 14.7 psi).
a. 6.80 atm
b. 100 atm
c. 1470 atm
d. 760 atm
9. 5.00 moles of iron was reacted with 2.00 moles of O2 according to the following reaction:
4 Fe (s) + 3 O2 (g) ---> 2 Fe2O3 (s)
Which reactant is the limiting reactant, and how many moles of product are formed respectively?
a. Fe, 2.00 mol
b. Fe, 2.50 mol
c. O2, 1.34 mol
d. O2, 2.00 mol
10.8. A 9.99g sample of an oxide of copper contains 2.00g of Oxygen “O”. What is the empirical formula
of this oxide?
a. Cu2O3
b. CuO
c. CuO2
d. Cu2O
11. A gas occupies 0.255 L at a pressure of 0.974 atm at 298 K. How many moles of gas are present? The
gas constant R = 0.08206 (L atm) / (mol K).
a. 0.00284 mol
b. 0.0101 mol
c. 0.112 mol
d. 0.0197 mol
12. How many copper atoms are in 25.0 g of copper metal?
a. 3.19 X 1023 atoms
b. 6.022 X 1023 atoms
c. 1.46 X 1023 atoms
d. 2.37 X 1023 atoms
13. In the following reaction, 2 Fe (s) + 3 Cl2 (g) → 2 FeCl3 (s)
if we start with 27.9 g of Fe and 35.45 g of Cl2, which is the reactant in excess?
a. FeCl3
b. 2Fe
c. Cl2
d. Fe
14. A gas is initially has a volume of 500 L at -STP. What is the volume at 25.0°C if the pressure remains
at 1.00 atm? The gas constant R = 0.08206 (L atm) / (mol K).
a. 480 L
b. 765 L
c. 624 L
d. 546 L
15. In the following reaction, 2 Cu (s) + S (s) → Cu2S (s)
if we start with 5.00 g of copper and react it with excess sulfur, how many grams of Cu2S will be formed?
a. 10.44 g
b. 5.83 g
c. 6.26 g
d. 8.09 g
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16. 0.255 moles of gas occupy a volume of 4.55 L at a temperature of 25.0°C. What is the pressure of gas
present in atms? R = 0.08206 (L atm)/(mol K)
a. 0.115 atm
b. 8.70 atm
c. 0.730 atm
d. 1.37 atm
17. Identify each gas law, which of the following is also called Boyle’s law:
a. P1V1 = P2V2
b. V1/T1 = V2/T2
c. P1/T1 = P2/T2
d. PV = nRT
18. If a gas, initially at 1.10 atm and 5.00 L, is compressed to a volume of 2.00 L, what is the new
pressure of the gas?
a. 9.09 atm
b. 2.75 atm
c. 2.20 atm
d. 0.440 atm
19. A gas initially has a volume of 500 L and a pressure of 1.05 atm at 25.0°C. What is the volume of the
gas when the pressure is reduced to 0.450 atm and the temperature is reduced to 5.00°C?
a. 1088 L
b. 974 L
c. 1267 L
d. 848 L
20. An oxide of silicon is 46.74% Si and 53.26% O by mass. What is the empirical formula of the oxide?
a. Si2O3
b. Si2O
c. SiO2
d. SiO
21. A student reacted 1.00 g of aluminum metal with excess oxygen, forming aluminum oxide:
4 Al (s) + 3 O2 (g) ---> 2 Al2O3 (s)
If the student obtained 1.51 g of Al2O3, what was the percent yield?
a. 79.8%
b. 69.0%
c. 97.8%
d. 86.5%
22. A gas occupies 500 mL at STP. How many moles of gas are present? (Recall the number 22.4 for this
calculation!)
a. 11.2 mol
b. 44.8 mol
c. 0.0223 mol
d. 0.500 mol
23. The combustion of propane is given by the following reaction:
C3H8 (g) + 5 O2 (g) ---> 3 CO2 (g) + 4 H2O (g)
If 5.00 L of propane are burned in the presence of excess O2, how many liters of carbon dioxide will be
formed?
a. 15.0 L
b. 10.0 L
c. 5.00 L
d. 20.0 L
24. The decomposition of calcium carbonate is shown by the following reaction:
CaCO3 (s) ---> CaO (s) + CO2 (g)
If you start with 10.0 g of calcium carbonate, how many grams of calcium oxide will be formed?
a. 5.57 g
b. 8.43 g
c. 6.24 g
d. 4.77 g
25. How many moles of hydrogen atoms are in 10.0 g of water, H2O?
a. 1.11 mol
b. 0.278 mol
c. 0.760 mol
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d. 0.555 mol
26. How many moles of an ideal gas occupy 525 L at STP?
a. 25.9 L
b. 21.6 L
c. 22.7 L
d. 23.4 L
27. Which gas properties are inversely related?
a. Pressure and Temperature
b. Volume and Temperature
c. Volume and Amount
d. Volume and Pressure
28. In the following reaction for the synthesis of ammonia, N2 (g) + 3 H2 (g) → 2 NH3 (g)
If we start with 0.500 mol of H2 gas and react it with excess N2 gas, how many moles of NH3 will be
formed?
a. 0.333 mol of NH3
b. 0.250 mol of NH3
c. 1.50 mol of NH3
d. 3.00 mol of NH3
29. How many moles of H2 are there in 1 mole of H2O?
a. 1
b. 2
c. 6.02 x 1023
d. 22.4 mole
30. What is the formula of nitric acid?
a. NO3H
b. HNO3
d. HNO2
c. H2NO3
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