Chem. 10

Test 4

Multiple Choice. Choose the best answer.

  1. Which of the following is not a property of a solution?
  1. Is always homogeneous
  2. Settles out on standing
  3. The composition maybe varied
  4. The components may be separated by physical means.
  5. Each component retains its properties.
  1. The solubility of a substance in water at 25oC is known to be 1.25 g per 100.0 mL of water. What is the

    2. minimum volume of water needed to dissolve 0.75 g of this substance at this temperature?

    a. 60.0 mL b. 167 mL c. 1.67 mL d. 133 mL e. 80.0 mL

  2. Calculate the % by mass of NaCl in a solution that contains 3.00 g of NaCl per 100.0 g of water.

a. 3.00 b. 97.0 c. 3.09 d. 2.91 e. 97.1

4. How many moles of NH3 are in 25.0 mL of an aqueous solution of 1.50 M NH3?

a. 37.5 b. 16.7 c. 0.0375 d. 0.638 e. none of these
  1. How many grams of KOH would be needed to prepare 400. mL of 0.300 M KOH solution?

    2. a. 56.1 b. 0.120 c. 42.8 d. 3.36 e. 6.73

  2. What volume of 12.0 M HCl would be required to prepare 200. mL of 1.00 M HCl?

    3. a. 0.833 L b. 83.3 mL c. 2.40 L d. 1.00 mL e. 16.7 mL

  3. What is the freezing point of an aqueous solution that is 1.50 molal in a nonionic solute?

    4. For water: Kf = 1.86oC/m

    a. -2.79oC b. -0.78oC c. +0.78oC d. 275. K e. +2.79oC

  4. Which of the following molecules is most likely to dissolve in water?

a. C6H6 b. SiC c. C2H5OH d. N2 e. CH4

9. The solubility of NaCl in water is 37.0 g per 100 mL of water at 30oC. If 12.0 g NaCl is mixed with 40.0

mL of water at this temperature, which of the following is most likely to happen?

    1. All will dissolve and the solution is saturated.
    2. All will dissolve and the solution is unsaturated.
    3. All will dissolve and the solution is supersaturated.
    4. Some will dissolve and the solution is saturated.
    5. None of the above.
  1. For which of the following aqueous solutions would the molarity and normality be the same?

    2. a. Sr(OH)2 b. H3PO4 c. Al(OH)3 d. HNO3 e. BaCl2

  2. What is the definition of the term activation energy?
  1. the energy of a neutral atom
  2. the maximum energy of a molecule undergoing change
  3. the minimum energy that a molecule must have in order to undergo chemical change
  4. the average energy of all molecules undergoing change
  5. the difference between the energy of the product and the energy of the reactant

 

 

 

  1. Consider the reaction A(g) + 2B(g) « C(g) to have attained chemical equilibrium. Determine the value of the equilibrium constant, K, if the equilibrium concentrations of the gases are:

[A] = 0.050 M, [B] = 0.050 M, [C] = 0.003M

a. K = 0.060 b. K = 0.042 c. K=1.2 d. K=0.83 e. K=24

13. Consider the reaction 2NO2(g) « N2O4(g) to have attained chemical equilibrium. If the equilibrium

constant, K = 2.5 and [NO2]=0.30, determine [N2O4].

a. 0.75 M b. 0.22 M c. 8.3M d. 0.12 M e. 0.036M

Nos.14-17. Consider the hypothetical exothermic reaction A(g) + 2B(g) « C(g) + 4D(g)

to have attained equilibrium at constant temperature and pressure

Determine the direction of the Le Chatelier shift resulting from the following changes:

[Use a = forward; b = backward, c= no effect]

#14. Addition of more A

#15. Increase in pressure

#16. Addition of a catalyst

#17. Cooling

  1. Consider the above reaction in #14. If it is desired to produce more D, which of these

will most probably work?
  1. increase the pressure and heat
  2. increase the pressure and cool
  3. decrease the pressure and heat
  4. decrease the pressure and cool
  5. none of the above
  1. Which of the following is not a property of an acid?
  1. turns blue litmus red
  2. liberates hydrogen gas with an active metal
  3. reacts with a base to form a salt and water
  4. produces carbon dioxide gas when reacted with a carbonate
  5. is red with phenolphthalein
  1. What is the conjugate acid of H2O?

a. H2O b. H3O+ c. H2O+ d. OH- e. O2-

21. Consider the reaction: CO32- + H20 « HCO3- + OH-

Which of these constitutes a conjugate acid- base pair?

    1. CO32- and H2O
    2. CO32- and OH-
    3. H2O and HCO3-
    4. H2O and OH-
    5. none of these

22. Which of these is completely ionized in aqueous solution?

a. HF b. HCN c. HCl d. H2S e. HNO2

 

 

 

 

 

  1. Which of these is not a good electrical conductor in aqueous solution?

    2. a. NaOH b. KOH c. Ba(OH)2 . d. NH4OH e. Ca(OH)2

  2. At the same molarity, which of the following acids will have the highest [H3O+]?

a. HI b. HCN c. HF d. H2S e. HC2H3O2

25. Calculate the pH of a solution whose [OH-] = 5.0 x 10-10M

a. 5.00 b. 4.70 c. 10.0 d. 0.70 e. 9.30

26. A sample of blood has a pH of 7.34. Determine the [H3O+] of this sample.

    1. 4.6 M
    2. 2.2 x 10-9 M
    3. 6.5 x 10-4 M
    4. 8.7 x 10-1 M
    5. 4.6 x 10-8 M

27. Consider the reaction Mg(s) + 2HCl(aq) ------> MgCl2(aq) + H2(g)

When this equation is written in net ionic form, it becomes

a. Mg + 2H+ ------> Mg2+ + H2

b. 2H+ ------> H2

c. Mg + 2Cl- -------> MgCl2

d. 2HCl -----> H2 + 2Cl-

e. This equation does not have a net ionic form.

  1. If a solution conducts electricity, it is positive evidence that…
  1. it contains a strong acid or a strong base
  2. mobile ions are present
  3. it is pure water
  4. the solute is not an organic compound
  5. molecules are present
  1. According to the Bronsted-Lowry definition, an acid …
  1. yields H3O+ ions in aqueous solution
  2. yields OH- ions in aqueous solution
  3. is a proton acceptor
  4. is a proton donor
  5. is all of the above
  1. A solution is prepared by dissolving 0.0010 mole NaOH in 1 liter of solution. What are the pH

    2. and pOH of this solution?

    pH pOH

    a. 3 11

    b. 3 3

    c. 11 3

    d. -11 -3

    e. 10-11 10-3

     

     

     

     

     

  2. In a redox reaction, the oxidizing agent;;
  1. loses electrons
  2. is oxidized
  3. gains electrons
  4. increases in oxidation number
  5. does all of the above

#32-36. Consider the following:

32. HCHO 33. KClO4 34. AsH3 35. C6H6 36. P2O5

Determine the oxidation number of each of the underlined elements.

Use the following values:

a. 0 or -1 b. +1 to +3 c. +4 to +6 d. less than -1 e. greater than +6

#37-39. Classify each of the following as: a) oxidation half-reaction b) reduction half-reaction or

c) neither

37. SO2 ----> SO32-

38. C2O42- ----> CO2

39. I2 ------> 2I-

  1. Which of the following statements is untrue for an electrochemical cell?
  1. Oxidation occurs at the anode.
  2. Reduction occurs at the cathode.
  3. An electrochemical cell maybe voltaic or electrolytic
  4. An electrochemical cell results from a redox reaction.
  5. In an electrochemical cell, electrons flow through the electrolyte.

 

R x 3 = 120 points