Unit 4 Test Study Guide

Which of the following best describes the change that takes place immediately after the

CH3

OH(l) is introduced into the previously evacuated vessel?

• A A chemical change takes place because covalent bonds are broken.

• B A chemical change takes place because intermolecular attractions are overcome.

• C A physical change takes place because covalent bonds are broken.

• D A physical change takes place because intermolecular attractions are overcome.

2 H2 O2(l) → 2 H2 O(l) + O2(g)

The exothermic process represented above is best classified as a

• A physical change because a new phase appears in the products.

• B physical change because O2(g) that was dissolved comes out of solution

• C chemical change because entropy increases as the process proceeds.

• D chemical change because covalent bonds are broken and new covalent bonds are

  formed.

HCl(aq) + NaOH(aq) → NaCl(aq) + H2 O(l)

A student had two dilute, colorless solutions, HCl(aq) and NaOH(aq), which were at the same

temperature. The student combined the solutions, and the reaction represented above

occurred. Which of the following results would be evidence that a chemical reaction took

place?

• A The resulting solution is colorless.

• B The temperature of the reaction mixture increases.

• C The total volume of the mixture is approximately equal to the sum of the initial

  volumes.

• D The resulting solution conducts electricity.

A student was asked to formulate a hypothesis about what would happen if 100.mL of

0.1MNaOH(aq) at 25°C was combined with 100.mL of 0.1MMgCl2(aq) at 25°C .

Which of the following hypotheses indicates that the student thought a chemical change

would occur?

• A The volume of the resulting solution will be equal to the sum of the volumes of the

  original solutions.

• B The mass of the resulting solution will be equal to the sum of the masses of the original

  solutions.

• C The resulting solution would contain a precipitate.

• D The resulting solution will be clear.

A student was studying physical and chemical changes. The student carried out some

procedures in the laboratory and recorded observations. For one of the procedures,

the student concluded that a physical change took place, but not a chemical change.

Which of the following could have been the results of the procedure?

• A A cube of metal was changed into a flat sheet of metal.

• B When two liquids at room temperature were combined in a beaker, the beaker became hot.

• C When two clear liquids were combined, the resulting mixture was cloudy.

• When a colorless liquid was added to a blue liquid, the resulting solution was yellow.

At 127°C, the pressure in vessel 1 is found to be higher than that in vessel 2. Which of the

following reactions best accounts for the observation?

• A NaHCO3(s) → Na(s) + HCO3(s)

• B NaHCO3(s) → NaH(s) + CO3(s)

• C 2 NaHCO3(s) → Na2 CO3(s) + CO2(g) + H2 O(g)

• D 2 NaHCO3(s) + N2(g) → 2 NaNO3(s) + C2 H2(g)

Which of the following is the net ionic equation for the reaction between aqueous sodium fluoride and hydrochloric acid?

• A NaF(aq) + HCl(aq) → NaCl(aq) + HF(aq)

• B Na+ (aq) + F− (aq) + H+(aq) + Cl−(aq) → Na+(aq) + Cl− (aq) + HF(aq)

• C Na+(aq) + Cl−(aq) → NaCl(aq

• D F−(aq) + H+(aq) → HF(aq)

Equal volumes of 0.2M solutions of lead(II) nitrate and potassium bromide are

combined to form lead(II) bromide as a yellow precipitate. Which of the following is the

correct net ionic equation for the reaction?

• A Pb2+ (aq) + 2Br− (aq) → PbBr2(s)

• B K+(aq) + NO3−(aq) → KNO3(aq)

• C Pb2+aq) + 2NO3−(aq) + 2K+(aq) + 2Br−(aq) → 2K+(aq) + 2NO3−(aq) + PbBr2(s)

• D Pb(NO3)2(aq) + 2KBr(aq) → PbBr2(s) + 2KNO3(aq)

The reaction between aqueous strontium chloride (SrCl2) and aqueous potassium sulfate(K2SO4) forms a precipitate of strontium sulfate (SrSO4) . Which of the following

represents the net ionic equation for the reaction?

• A Cl−(aq) + K+(aq) → KCl(aq)

• B Sr2+(aq) + SO42−(aq) → SrSO4(s)

• C Sr2+(aq) + 2Cl−(aq) + SO42−(aq) + 2K+(aq) → SrSO4(s) + 2Cl−(aq) + 2K+(aq)

• D SrCl2(aq) + K2SO4(aq) → SrSO4(s) + 2KCl(aq)

. . . C10H12O4 S(s) + . . . O2(g) → . . . CO2(g) + . . . SO2(g) + . . . H2O(g)

When the equation above is balanced and all coefficients are reduced to their lowest

whole-number terms, the coefficient for O2(g) is

• A 6

• B 7

• C 12

• D 14

• E 28