PHY2253
Fall 2013
Name:
Exam 2
Multiple Choice: Mark the choice on your scantron that best answers the question or completes the statement.
1. The process of melting ice into water is an example of
a.
b.
a physical change.
a chemical change.
c. both chemical and physical change
d. neither physical nor chemical change
2. Which of the following does not take place in a chemical reaction?
a.
b.
New substances are formed.
Neutrons are released.
c. Energy is released or absorbed.
d. Reactants disappear.
3. The substances that are diminished in a chemical reaction are called the
a.
products.
b. reactants.
c. chemicals.
d. precipitates.
4. The equation 4H2O2  4H2O + 2O2 is not appropriately written because
a.
b.
c.
d.
oxygen is not diatomic.
fractional coefficients are not generally used.
the number of atoms of each element on each side is not the same.
the simplest set of coefficients has not been used.
5. When the equation Sb2S3 + HCl  SbCl3 + H2S is balanced, thesum of all the coefficients is:
a. 10.
b. 14.
c. 9.
d. 12.
6. When the equation Al + O2  Al2O3 is balanced, the coefficient of Al is
a. 1
b. 2
c. 3
d. 4
7. What basic type of reaction is illustrated by the general equation AB  A + B?
a.
Combination
b. Decomposition c. Double-replacement
d. Single-replacement
8. When a hydrocarbon or carbon-hydrogen-oxygen compound is burned completely, the products are
a.
CO2 and H2O.
b. CH2 and O2. c. CO and H2.
9. The formula mass of sulfuric acid, H2SO4, is
a. 98 amu.
b. 100 amu.
d. C and H2.
c. 66 amu.
d. 7 amu.
10. The energy necessary to start a chemical reaction is called the ______________ energy.
a.
Exothermic
b. activation
c. endothermic
d. combustion
11. When there is a release of heat by a chemical reaction, it is called a(n) ______________ reaction.
a.
Exothermic
b. activation
c. endothermic
d. combustion
12. Increased temperature usually leads to an increase in reaction rate because collisions are
a.
b.
more violent only (stronger).
more frequent only.
c. both more violent and more frequent.
d. none of these
PHY2253
13. The rate of a chemical reaction would be increased by
a.
b.
c.
d.
Fall 2013
increasing the surface area of the reactants.
increasing the concentration of the reactants.
adding a catalyst to the reactants.
all of the above.
14. A solution with a pH of 14 is
a.
strongly acidic.
b. weakly basic.
c. strongly basic. d. weakly acidic.
15. An acid added to a base will produce a
a.
b.
salt and hydrogen ions.
salt and hydroxide ions.
c. salt and water.
d. stronger acid and base.
16. Acids are characterized by the presence of what kind of ion?
a. SO42b. Clc. OHd. H+
17. Which of the following compounds would you expect to be soluble in water?
a. PbCO3
b. Ag2CO3
c. CuCO3
d. K2CO3
18. When solutions of AgNO3 and CaCl2 are mixed, which type of reaction is likely?
a.
Combination
b. Double-replacement
c. Decomposition d. Single-replacement
19. For the reaction in the previous question, what is the formula for the solid product (the precipitate)?
a. AgNO3
b. CaCl2
c. AgCl
d. Ca(NO3)2
20. Which type of reaction is Zn + 2HCl ZnCl2 + H2?
a.
Decomposition
b. Combination
c. Double-replacement
d. Single-replacement
21. What would be the molarity of a solution that contained 25 g of NaCl in 2.50 L of water?
a. 0.42 M
b. 0.17 M
c. 25 M
d. 10. M
22. Avogadro's number has a numerical value of
a. 6.02 x 1023.
b. 1.00 x 1023.
c. 3.01 x 1023.
d. none of these.
23. How many moles would 44 g of carbon dioxide, CO2, be?
a. 3.0
b. 2.0
c. 1.0
d. None of these
24. The percentage by mass of hydrogen in methane, CH4, is about
a. 25%.
b. 75%.
c. 80%.
d. 20%.
25. A compound consists of only magnesium, carbon, and oxygen. If the percentage by mass of Mg is 74.9% and that
of C is 19.2%, what is the percentage by mass of O?
a. 94.1%
b. 5.9%
c. 55.7%
d. 83.7%
PHY2253
Fall 2013
True False: Mark “A” on your scantron if the statement is true; Mark “B” if it is false.
26. A solution of 10.0 M is more concentrated than a solution with a molarity of 2.0 M.
a. True
b. False
27. An endothermic reaction causes the surroundings to become cooler.
a. True
b. False
28. A chemical reaction is balanced when the number of coefficients on the reactant side equals the number of
coefficients on the product side.
a. True
b. False
29. On a graph of molar concentration versus time, the slope is equal to the reaction rate.
a. True
b. False
30. In general, transition metals cause solids to be insoluble in water.
a. True
b. False
31. The units of amu and g/mol are equivalent and interchangeable.
a. True
b. False
32. Combustion reactions are always endothermic.
a. True
b. False
33. Avogadro’s number is equal to the number of particles in 1 mole of any substance.
a. True
b. False
34. Phase changes, like melting, freezing, and boiling, are always chemical changes.
a. True
b. False
35. Ca(OH)2 would be soluble, whereas Fe(OH)2 would not.
a. True
b. False
PHY2253
Fall 2013
Name:
Exam 2, Written Section
1. Balance each of the following chemical reactions and indicate the type of chemical reaction that is occurring:
a.
HNO3 +
Ba(OH)2 
H2O +
Ba(NO3)2
type of rxn:
b.
Na +
F2 
NaF
type of rxn:
c.
Na3PO4 +
FeCl3 
NaCl +
FePO4
type of rxn:
2. Are any of the reactions above precipitation reactions? If so, which one(s)? How do you know?
3. A chemical solution is prepared using 45 grams of lithium sulfate (Li2SO4) . Answer these questions about it.
a. What is the molar mass of the lithium sulfate solute?
b. How many moles of lithium sulfate are present?
c. What would be the molarity if the lithium sulfate were dissolved in 500. mL of water?
BONUS: Write and balance the equation using only the reactants. Include the physical states for the products. For an
extra point, write the chemical names below each of the reactants and products.
Ba(NO3)2(aq) + K2CO3(aq) 