Chemistry Final

1.

1 point

if the below reaction has Kc = 3.64 x 10^-3. What is the value of Kp for this reaction at 25º C?
2 NaN3(s) <--> 2 Na(s) + 3 N2(g)

0.613

8.90 x 10^-2

29.9

53.2

2.

1 point

Which has the highest molar solubility in pure water?

SnS, Ksp = 1.0 x 10^-26

CuS, Ksp = 1.27 x 10^-36

Fe(OH)3, Ksp = 2.79 x 10^-39

ZnS, Ksp =2.0 x 10^-25

3.

1 point

If the first-order reaction, 2 N2O(g) --> 2N2(g) + O2(g) has a rate constant equal to 0.76 s^-1 at 1000 K, how long will it take for the concentration of N2O to decrease to 12% of its initial concentration?

0.62 s

2.8 s

6.3 s

8.4 s

4.

1 point

What is the percent ionization of this acid?

27%

55%

81%

91%

5.

1 point

PbO2(s) + SO4^2-(aq) + 4H^+(aq) + 2Hg(l) + 2Cl-(aq) --> Hg2Cl2(s) + PbSO4(s) + 2H2O(l)
Which is the oxidizing agent (oxidant) in this reaction?

SO4^2-

PbO2

Cl-

Hg

6.

1 point

PbO2(s) + SO4^2-(aq) + 4H^+(aq) + 2Hg(l) + 2Cl-(aq) --> Hg2Cl2(s) + PbSO4(s) + 2H2O(l)
Which is the reducing agent (reductant) in this reaction?

SO4^2-

PbO2

Cl-

Hg

7.

1 point

Which is the solubility-product expression for chromium (III) carbonate?

[Cr^3+]^2[CO3^2-]^3

not this one

8.

1 point

Which correctly compares this acid with propanoic acid, CH3CH2COOH, pKa = 4.88?

the acid in the diagram has a less stable conjugate base than CH3CH2COOH, so CH3CH2COOH is stronger

the acid in the diagram has a more stable conjugate base than CH3CH2COOH, so CH3CH2COOH is weaker

the acid in the diagram has a less stable conjugate base than CH3CH2COOH, so CH3CH2COOH is weaker

the acid in the diagram has a more stable conjugate base than CH3CH2COOH, so CH3CH2COOH is stronger

9.

1 point

PbO2(s) + SO4^2-(aq) + 4H^+(aq) + 2Hg(l) + 2Cl-(aq) --> Hg2Cl2(s) + PbSO4(s) + 2H2O(l)
How many moles of electrons are transferred in this reaction?

1

2

4

6

10.

1 point

If the graph below corresponds to the reaction, which correctly explains the equilibrium constant?
A <--> 2B

Kc < 1

Kc = 0

Kc = 1

Kc > 1

11.

1 point

What is the freezing point of a solution of 1.43 g MgCl2 in 100 g water? Kf for water is 1.86ºC

-0.0279º C

-0.279º C

-0.559º C

-0.838º C

12.

1 point

Which diagram displays the system with the second highest entropy?

drawing (a)

drawing (b)

drawing (c)

drawing (d)

13.

1 point

Which two liquids are immiscible in one another?

CS2 and H2O

CH3OCH3 and H2O

CBr4 and CH3CH2CH2CH2CH2CH3

CH3CH2CH2CH2CH2CH3 AND C6H6

14.

1 point

Which is correct for the exothermic reaction below?
PCl3(g) + Cl2(g) --> PCl5(g)

spontaneous at all temperatures

nonspontaneous at all temperatures

spontaneous at low temperatures

spontaneous at high temperatures

15.

1 point

If a lightbulb draws a current of 9.5 x 10^-2 A, how many electrons pass through the bulb in one hour?

342

5.50 x 10^7

3.30 x 10^7

2.13 x 10^21

16.

1 point

A common rule of thumb in organic chemistry is that increasing the temperature of a reaction at room temperature by 10ºC doubles the rate. Calculate Ea for a reaction that follows this rule of thumb. Assume room temperature is 25ºC

0.576 kJ

12.2 kJ

38.4 kJ

52.9 kJ

17.

1 point

Which is the strongest oxidizing agent?

Cl2

K

Br2

Cu

18.

1 point

Al3+(aq) + 3 e- <--> Al(s) Eºred = -1.676 V
Sn2+ + 2 e- --> Sn(s) Eºred = -0.137 V
Which is the standard cell potential, Eºcell?

2.94 V

-2.94 V

1.54 V

4.75 V

19.

1 point

Al3+(aq) + 3 e- <--> Al(s) Eºred = -1.676 V
Sn2+ + 2 e- --> Sn(s) Eºred = -0.137 V
Which is the value of ∆Gº?

1702 kJ

-891 kJ

-1371 kJ

-1702 kJ

20.

1 point

What is the pH of this solution?

1.47

2.06

6.06

9.47

21.

1 point

After how many seconds will 5.43 g Ni onto an electrode from NiCl2(aq) using a current of 12.34 A?

0.0150 s

723 s

1447 s

17850 s

22.

1 point

What is the molecular formula for the compound below?

C9H18

C9H12

C9H14

C9H16

23.

1 point

Which is the oxidation state of technicium in TcO4-?

+1

+3

+7

+9

24.

1 point

Which is the function of the salt bridge in an electrochemical cell?

separates anions from cations

contains an ionic compound with a low Ksp

facilitates ion flow against their concentration gradient`

promotes electrical neutrality in the cell

25.

1 point

Calculate the pH of a solution formed by mixing 250.0 mL of 0.15 M NH4Cl with 100.0 mL of 0/20 M NH3. The Kb for NH3 is 1.8 x 10^-5

9.13

9.53

4.74

8.98

26.

1 point

What is the relationship between the molecules shown below?

identical

constitutional isomers

enantiomers

diastereomers

27.

1 point

Given kH=0.159 mol/(L•atm) for CH3Br, which is solubility in water at 25ºC and at a partial pressure of 250 mmHG?

0.0523 mol/L

0.329 mol/L

0.483 mol/L

39.8 mol/L

28.

1 point

Which acid has the lowest pKa?

HClO4

HBrO

HClO

HIO

29.

1 point

Which statement is correct for the titration of a weak base with strong, monoprotic acid?

pH will be 7 at the equivalence point

pH will be greater than 7 at the equivalence point

titration will require more moles of the base than acid to reach the equivalence point.

pH will be less than 7 at the equivalence point

30.

1 point

For a 0.001-molal solution of (NH4)2CO3, the van't Hoff factor, i, would be about

1

2

3

4

31.

1 point

What is t1/2 for a reaction with rate constant 0.54 M s^-1 and a 0.33 M initial reactant concentration?

0.089 s

1.8 s

0.31 s

5.6 s

32.

1 point

Which is correct if, upon dissolving an ionic solid in water, the temperature decreases?

|∆Hº solute| > |∆Hº solvent|

|∆Hº mix| < |∆Hº solute + ∆Hº solvent|

|∆Hº mix| < |∆Hº solvent|

33.

1 point

Which statement is true concerning the standard states of F2(g) and C6H12O6(aq)?

for F2(g), it is pure gas at 1 atm and for C6H12O6(aq) is the pure solid at 1 atm

for F2(g), it is pure gas at 1 mol/L and for C6H12O6(aq) is the pure solid at 1 atm

for F2(g), it is pure gas at 1 atm and for C6H12O6(aq) is the solution at a concentration of 1 mol/L

for F2(g), it is pure gas at 1 mol/L and for C6H12O6(aq) is the solution at a concentration of 1 mol/L

34.

1 point

If a * represents the conditions in Question 8, which diagram is consistent with the outcome?

A

B

C

D

35.

1 point

What is the pKa for this acid?

-0.60

1.18

1.89

5.98

36.

1 point

A solution is prepared by dissolving 17.75 g sulfuric acid, H2SO4, in enough water to make 100.0 mL of solution. If the density of the solution is 1.1094 g/mL, what is the mole fraction H2SO4 in the solution?

0.0181

0.0338

0.0350

19.0

37.

1 point

What is the value of Kc, if [PI5]eq = 0.56 M,[PI3]eq = 0.23 M, [I2]eq = 5.5 M at 25ºC?
PI5(g) <--> PI3(g) + I2(g)

2.3

0.93

0.44

1.1

38.

1 point

B4C(s) <--> 4 B(g) + C(s) ∆Gº= 775 kJ
Which statement is correct if the reaction vessel contains 4.00 mol B4C(s), 4.00 mol of C(s), and B(g) at a partial pressure of 1.0 x 10^-5 atm in 1.00 L volume solution?

∆G = -270 kJ; spontaneous

∆G = -270 kJ; nonspontaneous

∆G = -220 kJ; spontaneous

∆G = -220 kJ; nonspontaneous

39.

1 point

What effect will increasing the pressure have on the system?
Fe3O4(s) + CO(g) <--> 3 FeO(s) + CO2(g) ∆Hº = +35.9 kJ

The reaction will shift to the left in the direction of reactants

The equilibrium constant will decrease

No effect will be observed

The reaction will shift to the right in the direction of products

40.

1 point

If the rate of disappearance of HBr in the gas phase reaction
2HBr(g) --> H2(g) + Br2(g)
is 0.301 M s^-1 at 150ºC, which is the rate of Br2 production?

1.66

0.151

0.0906

0.602

41.

1 point

Which reaction occurs nonspontaneously?

3 Na+(aq) + Al(s) --> 3 Na(s) + Al3+(aq)

Cu(s) + 2 Ag+(aq) --> Cu2+(aq) + 2 Ag(s)

Fe(s) + CuSO4(aq) --> FeSO4(aq) + Cu(s)

Mg(s) + 2 H+(aq) --> Mg2+(aq) + H2(g)

42.

1 point

The disaccharide maltose is hydrolyzed into two moles of glucose, as shown left. Which accurately describes this process?

spontaneous; ∆Gº = -16.4 kJ

spontaneous; ∆Gº= -1257.6 kJ

nonspontaneous; ∆Gº= 1257.6 kJ

nonspontaneous; ∆Gº= 16.4 kJ

43.

1 point

If 2.10 g are lost from one electrode, which is true for the other electrode?

gain of 0.318 g

loss of 13.9 g

gain of 13.9 g

loss of 0.318 g