Chapter 4 Practice Test

Question 1

Which of these is likely to be the best conductor of electricity?

Answer 1

a sample of ocean water

Question 2

Which of these is an example of a solution?

Answer 2

air

Question 3

An aqueous solution of sodium chloride is placed in an electric circuit. A light bulb connected to the circuit is weakly illuminated, showing that a weak current is passing through it. How can the conductivity of the solution be increased?

Answer 3

by adding calcium chloride (CaCl2 ) to the solution

Question 4

You have 250 mL of a 0.80 M solution of silver nitrate AgNO3 (169.87 g / mol) dissolved in water. How many grams of AgNO3 does the solution contain?

Answer 4

34g

Question 5

You have a 12 M solution of hydrochloric acid HCl (36.5 g / mol). How many milliliters of the original solution do you need in order to make 500 mL of a 0.50 M solution of HCl?

Answer 5

21 mL

Question 6

Suppose 26 g of calcium chloride CaCl2 (110.98 g / mol) are dissolved in water to make 200 mL of solution. How many times greater is the molarity of chloride ions (Cl − ) than the molarity of calcium ions (Ca2+ ) in the solution?

Answer 6

2.0

Question 7

Solid iodine (I2 ) is nearly insoluble in water, somewhat soluble in ethanol, and very soluble in hexane. Based on this information, what can you conclude about I2?

Answer 7

It contains a nonpolar bond.

Question 8

The compound CH3(CH2 )4CH2OH is only slightly soluble in water. (This compound is identical to hexane except that one of the hydrogen atoms has been replaced with the −OH group of an alcohol.) A second compound has the formula HOCH2(CH2 )4CH2OH. (It is identical to the first compound except that it has two −OH groups instead of one.) How is the solubility of the second compound likely to compare to that of the first compound in water?

Answer 8

The second compound is likely to be more soluble in water.

Question 9

Which of the following processes is an example of increasing entropy?

Answer 9

Sugar dissolving in water.

Question 10

A solution of barium nitrate (Ba(NO3 )2 ) is combined with a solution of copper(II) sulfate (CuSO4 ). What is the overall precipitation reaction that will occur?

Answer 10

Ba2+ + 2NO3− + Cu2+ + SO42− → BaSO4 (s) + 2NO3− + Cu2+

Question 11

A solution of silver nitrate (AgNO3 ) is added to a solution of sodium hydroxide (NaOH). In the precipitation reaction that occurs, which ions will be spectator ions?

Answer 11

Na+ and NO3−

Question 12

The net ionic equation of a precipitation reaction is as follows.

2Al 3+ + 3CrO42− → Al2 (CrO4 )3 (s) 

Which of these pairs of solutions could have been combined to cause this reaction?

Answer 12

a solution of Al(NO2 )3 and a solution of K2CrO4

Question 13

Which of these compounds is an acid in aqueous solution?

Answer 13

H2SO4

Question 14

You have two colorless aqueous solutions, X and Y. You also have an indicator that turns purple in basic solutions, green in neutral solutions, and red in acidic solutions. Solution X turns purple when you add a small amount of the indicator to it. When you then add 5 mL of Solution Y to Solution X, the resulting mixture turns green. What can you conclude about Solution Y?

Answer 14

It is acidic.

Question 15

Suppose 200 mL of a 0.001 M solution of NaOH is combined with 300 mL of a 0.002 M solution of HCl. How many moles of hydrogen ions does the final solution contain?

Answer 15

4 × 10^−4 mole H +

Question 16

What is the oxidizing agent in the following reaction?

Cl2(g) + 2Na+ (aq) + 2Br− (aq) → 2Na+ (aq) + 2Cl − (aq) + Br2(l)

Answer 16

Cl2(g)

Question 17

When you place a sample of an unknown metal in a solution of Cu(NO3 )2, the metal becomes coated with a layer of copper. When you place a sample of the metal in a solution of HCl, bubbles of hydrogen gas are formed. What can you conclude about the unknown metal based on this information?

Answer 17

It reduces both Cu2+ and H +.

Question 18

What is the total number of electrons transferred in the following oxidation-reduction reaction?
2Al(s) + 3Cu2+ (aq) + 6Cl − (aq) →
2Al 3+ (aq) + 6Cl − (aq) + 3Cu (s)

Answer 18

6

Question 19

It takes 52.6 mL of a 0.724 M solution of potassium hydroxide (KOH) to titrate 86.8 mL of a solution of nitric acid (HNO3 ). What is the molar concentration of the nitric acid solution?

Answer 19

0.439 M

Question 20

The solute in an acidic solution is an impure sample of oxalic acid (a diprotic acid). This solution is titrated with 49.8 mL of a 0.145 M solution of NaOH. What other piece of information will allow you to calculate the molar concentration of oxalic acid in the acidic solution?

Answer 20

the volume of the acidic solution

Question 21

A 0.0680 M solution of KOH is used to titrate 42.3 mL of H3PO4, a triprotic acid. The initial reading of the buret is 61.7 mL, and the final reading is 12.4 mL. What is the molar concentration of the H3PO4 solution?

Answer 21

0.0265 M

Question 22

Suppose that you titrate 18.8 mL of a solution of sodium sulfite (Na2SO3 ) with a 0.0772 M solution of potassium dichromate (K2Cr2O7 ) in the presence of excess acid. The products of the titration reaction include sulfate ions, chromium(III) ions, and water. Which of the following pieces of information would allow you to calculate the concentration of the original sodium sulfite solution?

Cr2O72− + 3SO32− + 8H + → 2Cr3+ + 3SO42− + 4H2O

Answer 22

The volume of potassium dichromate used in the titration

Question 23

Suppose you dissolve 2.38 g of KMnO4 in water to make 500 mL of solution. It takes 41.3 mL of this solution to titrate 28.2 mL of an Fe2+ solution. Which of these calculations would not be necessary in order to find the concentration of the Fe2+ solution?

Answer 23

finding the mass of Fe2+ in the titrated solution

Question 24

A sample of water contaminated with lead nitrate (Pb(NO3 )2 ) has a volume of 30.7 mL. When an excess of sodium sulfate is added to the water, 0.0479 g of lead sulfate (PbSO4 ) precipitate. What was the original molar concentration of lead(II) ions (Pb2+ ) in the sample?

Answer 24

0.00515 M

Question 25

A 2.16 g sample of a silver alloy is dissolved in nitric acid. (An alloy is a solid solution of metals.) When an excess of sodium chloride is added to the solution, 1.42 g of AgCl precipitate. What is the percent by mass of silver in the alloy? (Assume that all the silver in the sample precipitates as AgCl.)

Answer 25

49.5%