chem exam 4 - multiple choice

Question 1

the dominant intermolecular forces in diethyl ether CH3CH2OCH2CH3 are

Answer 1

london dispersion forces

Question 2

what is the most important type of force existing between molecules of HI?

Answer 2

dipole-dipole forces

Question 3

the dominant intermolecular forces in acetone (CH3COCH3) are

Answer 3

dipole-dipole forces

Question 4

what is the most important type of force existing between molecules of HCl?

Answer 4

dipole-dipole forces

Question 5

the theoretical van’t Hoff Factor (i) for sodium sulfate is

Answer 5

3

Question 6

the rate constant for a reaction is 2.50 s–1. What is the overall order of the reaction?

Answer 6

first

Question 7

which of the following aqueous solutions will have the highest osmotic pressure?

Answer 7

0.10 m Na3PO4

Question 8

what is the freezing point of a solution made by dissolving 3.50 g of potassium chloride
( M = 74.55 g/mol) in 100.0 g of water. Assume ideal behavior for the solution; Kf =1.86°C/m

Answer 8

-1.7 C

Question 9

when the reaction A –> B + C is studied, a plot ln[A]t vs. time gives a straight line with a positive slope. what is the order of the reaction?

Answer 9

first

Question 10

the theoretical van’t Hoff factor (i) for sodium phosphate is

Answer 10

4

Question 11

the rate constant for a reaction is 4.65 L mol–1 s-1. what is the overall order of the reaction

Answer 11

second

Question 12

which of the following aqueous solutions will have the lowest osmotic pressure?

Answer 12

0.05 m CaSO4

Question 13

consider the following reaction:
2A(g) + 3B(g) → 2C(g) + D(g)
if [C] is increasing at the rate of 4.0 mol L–1s–1, at what rate is [A] changing?

Answer 13

-4.0 mol L-1 s-1

Question 14

when the reaction A → B + C is studied, a plot 1/[A]t vs. time gives a straight line with a positive slope. what is the order of the reaction?

Answer 14

second

Question 15

when a chemical system is at equilibrium,

Answer 15

the concentrations of the reactants and products have reached constant values

Question 16

in order to write the correct mass-action expression for a reaction one must

Answer 16

have a properly balanced chemical equation

Question 17

which one of the following will give a solution with a pH > 7, but is not an Arrhenius
base in the strict sense?

Answer 17

CH3NH2

Question 18

the substance H2SO3 is considered

Answer 18

a weak Arrhenius acid

Question 19

select the pair of substances in that an acid is listed followed by its conjugate base

Answer 19

HCO3 - , CO3 2-

Question 20

consider the equilibrium reaction:
H2(g) + Br2(g) –> 2HBr(g),
which of the following correctly describes the relationship between Kc and Kp for the reaction?

Answer 20

Kp = Kc

Question 21

at elevated temperatures, carbon reacts with O2 to produce CO as follows:
C(s) + O2 (g) 2CO(g)
when 0.350 mol of O2 and excess carbon were placed in a 5.00-L container and heated, the equilibrium concentration of CO was found to be 0.060 M. What is the equilibrium constant, Kc, for this reaction

Answer 21

0.090

Question 22

which one of the following is not considered an Arrhenius base but can produce an
aqueous solution with a pH > 7?

Answer 22

CH3CH2NH2

Question 23

the substance H2SO3 is considered:

Answer 23

a weak Arrhenius acid

Question 24

neon atoms are attracted to each other by

Answer 24

london dispersion forces

Question 25

ammonia's unusually high melting point is the result of

Answer 25

hydrogen bonding

Question 26

which of the following atoms should have the greatest polarizability?

Answer 26

Pb

Question 27

which of the following should have the highest boiling point?

Answer 27

CI4

Question 28

in hydrogen chloride (HCl) _______ are the most important intermolecular forces

Answer 28

dipole-dipole forces

Question 29

what is the mole fraction of Ar in a mixture containing 10.1 g of Ne, 79.9 g of Ar, and 83.8 g of Kr?

Answer 29

0.57

Question 30

a solution of salt (NaCl) in water is in equilibrium with solid salt. if more solid salt is added, with stirring,

Answer 30

the concentration of the solution will remain the same

Question 31

consider the molecular substances CO2, NH3, and CH4. which of them is/are soluble in benzene (C6H6)

Answer 31

CO2 and CH4

Question 32

in hydrogen sulfide (H2S) _______ are the most important intermolecular forces

Answer 32

dipole-dipole forces

Question 33

which of the following has a boiling point that does not fit the general trend?

Answer 33

NH3

Question 34

when the reaction A → B + C is studied, a plot [A]t vs. t gives a straight line with a negative slope. What is the order of the reaction?

Answer 34

zero

Question 35

a reaction has the following rate law: Rate = k[A][B]2 in experiment 1, the concentrations of A and B are both 0.10 mol L–1; in experiment 2, the concentrations are both 0.30 mol L–1. If the temperature stays constant, what is the value of the ratio, Rate(2)/Rate(1)?

Answer 35

27

Question 36

ammonium cyanate (NH4CNO) reacts to form urea (NH2CONH2). At 65°C the rate constant, k, is 3.60 L mol–1s–1. what is the rate law for this reaction?

Answer 36

rate = 3.60 L mol-1 s-1 [NH4CNO]2

Question 37

which of the following sets of units could be appropriate for a zero-order rate constant?

Answer 37

mol L-1 s-1

Question 38

consider the following reaction: 5Br–(aq) + BrO3–(aq) + 6H+(aq) → 3Br2(aq) + 3H2O(aq) For this reaction, the rate when expressed as [Br2]/ t is the same as

Answer 38

-0.6 (delta) [Br]- / (delta) t

Question 39

sucrose decomposes to fructose and glucose in acid solution. when ln [sucrose] is plotted vs. time, a straight line with slope of –0.208 hr–1 can be obtained. what is the rate law for the reaction?

Answer 39

rate = 0.208 hr-1 [sucrose]

Question 40

when the reaction A → B + C is studied, a plot ln[A]t vs. time t gives a straight line with a negative slope. what is the order of the reaction?

Answer 40

first

Question 41

consider the reaction A + 2B → 2C + D If the rate law for this reaction is rate = k[A][B], what will be the effect on the rate if the concentrations of A and B are both doubled at the same time?

Answer 41

the rate will increase by a factor of 4

Question 42

considering the reaction A → B. At 65°C the rate constant, k, is 1.74 L mol–1s–1. what is the rate law for this reaction?

Answer 42

rate = 1.74 L mol-1s-1 [A]2

Question 43

which of the following sets of units could be appropriate for a first order rate constant?

Answer 43

s-1

Question 44

consider the following reaction: 5Br–(aq) + BrO3–(aq) + 6H+(aq) → 3Br2(aq) + 3H2O(aq) for this reaction, the rate when expressed as Δ[Br2]/Δt is the same as

Answer 44

-3 (delta) [BrO3 -] / (delta) t

Question 45

sulfuryl chloride, SO2Cl2 (g), decomposes at high temperature to form SO2(g) and Cl2 (g). the rate constant at a certain temperature is 4.68 × 10-5s-1. what is the order of the reaction?

Answer 45

first

Question 46

what is the molality of a solution prepared by dissolving 86.9 g of diethyl ether, C4H10O, in 425 g of benzene, C6H6?

Answer 46

2.76 m

Question 47

human blood has a molar concentration of solutes of 0.30 M. What is the osmotic pressure of blood at 25°C?

Answer 47

7.3 atm

Question 48

which of the following aqueous solutions will have the lowest freezing point?

Answer 48

0.10 m CaCl2

Question 49

the following reaction is at equilibrium in a sealed container. N2(g) + 3H2(g) 2NH3(g) ΔH°rxn < 0 which, if any, of the following actions will increase the value of the equilibrium constant, Kc?

Answer 49

lowering the temperature

Question 50

write the mass-action expression, Qc , for the following chemical reaction. Zn(s) + 2Ag+(aq) --> Zn2+(aq) + 2Ag(s)

Answer 50

[Zn 2+] / [Ag +]2

Question 51

which of the following aqueous liquids is the most acidic?

Answer 51

0.1 M Al(NO3)3, Ka = 1x10^-5

Question 52

what is the pH of a 0.00200 M HClO4 solution?

Answer 52

2.699

Question 53

a 0.050 M solution of the weak acid HA has [H3O+] = 3.77 × 10–4 M. What is the Ka for this acid?

Answer 53

2.8 x 10^-6 M

Question 54

a 1.25 M solution of the weak acid HA is 9.2% dissociated. what is the pH of the solution?

Answer 54

0.94

Question 55

Nitrogen dioxide decomposes according to the reaction 2NO2(g) --> 2NO(g) + O2(g) where Kp = 4.48 × 10–13 at 25°C. what is the value for Kc?

Answer 55

1.83 x 10^-14

Question 56

which, if any, of the following aqueous mixtures would be a buffer system?

Answer 56

H2CO3 , HCO3-

Question 57

what will be the effect of adding 0.5 mL of 0.1 M NaOH to 100 mL of an acetate buffer in which [CH3COOH] = [CH3COO–] = 0.5 M?

Answer 57

the pH will increase slightly

Question 58

when a weak acid is titrated with a weak base, the pH at the equivalence point is

Answer 58

determined by the sizes of Ka and Kb

Question 59

consider the reaction CuO(s) + H2(g) --> Cu(s) + H2O(l) in this reaction, which substances are the oxidant and reductant, respectively?

Answer 59

CuO and H2

Question 59

a voltaic cell is prepared using copper and silver. Its cell notation is shown below. Cu(s) | Cu2+(aq) || Ag+(aq) | Ag(s) which of the following processes occurs at the cathode?

Answer 59

Ag+(aq) + e- --> Ag(s)

Question 60

a cell can be prepared from copper and tin. What is the E°cell for the cell that forms from the following half-reactions? Cu2+(aq) + 2e– Cu(s) E° = 0.34 V Sn4+(aq) + 2e– Sn2+(aq) E° = 0.13 V

Answer 60

0.21 V

Question 61

consider the following balanced redox reaction Mn2+(aq) + S2O82–(aq) + 2H2O(l) → MnO2(s) + 4H(aq) + 2SO42–(aq) which of the following statements is true?

Answer 61

Mn2+(aq) is the reducing agent and is oxidized

Question 62

which of the following solids is commonly used as an inactive electrode in electrochemical cells?

Answer 62

graphite

Question 63

the line notation, Pt | H2(g) | H+(aq) || Cu2+(aq) | Cu(s), indicates that

Answer 63

copper metal is a product of the cell notation