Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Chemistry 142 > Old Exams > Flashcards

Old Exams Flashcards

You may prefer our related Brainscape-certified flashcards:
Periodic Table flashcards Chemistry 101 flashcards AP® Chemistry flashcards Organic Chemistry 101 flashcards
1
Q
  1. Methane gas burns in a furnace to produce carbon dioxide gas and water in the liquid state. What are the signs of ΔH, ΔS, and ΔG for this process?
    a. ΔH = - , ΔS = -, ΔG = +
    b. ΔH = - , ΔS = +, ΔG = -
    c. ΔH = + , ΔS = -, ΔG = +
    d. ΔH = + , ΔS = +, ΔG = -
    e. ΔH = - , ΔS = -, ΔG = -
A

e. ΔH = - , ΔS = -, ΔG = -

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

A reaction takes place within a system. As a result, the entropy of the system decrease. What must be true?
I. The reaction is exothermic
II. The entropy of the universe increases
III. The entropy of the surroundings increases
IV. Gibbs free energy of the system decreases
A. II and IV
B. II, III and IV
C. II and III
D. All are true

A

D. All are true

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why does a mixture of dye and water never “unmix”?

a. The process is irreversible
b. The entropy is too high
c. The dye and water molecules have more possible arrangements
d. The process is exothermic

A

c. The dye and water molecules have more possible arrangements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q 
Which process is exothermic?
I. Evaporation of a liquid
II. Braking a hydrogen molecule into hydrogen atoms
III. Freezing water
a. II
b. III
c. I
d. I and II
e. I and III
f. II and III
A

b. III

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the concentration of Na+ ions in a 0.20M solution of Na3PO4?

a. 0.067 M
b. 0.20 M
c. 0.60 M
d. 0.90 M

A

c. 0.60 M

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Ammonia solution is normally diluted for household use. What is the concentration of an ammonia solution prepared by taking 100 mL of 6.50 M ammonia and adding it to enough water to make 2.00 L of solution?

a. 0.130 M
b. 0.325 M
c. 0.650 M
d. 2.08 M

A

b. 0.325 M

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Ice is produced when liquid water freezes. What conditions would be most likely to produce ice?
Claim:
I. Low temperature
II. High temperature
Reasoning
III. The entropy is negative so the process always happens
IV. Both enthalpy and entropy changes are negative so the temperature must be low
V. Both enthalpy and entropy changes are positive so the temperature must be high
a. I and III
b. II and III
c. I and IV
d. II and IV
e. I and V
f. II and V

A

c. I and IV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q 
What stays the same when a solution is diluted?
I. Moles of the solvent
II. Volume of the solvent
III. Moles of the solute
IV. Concentration of the solution
a. III
b. I and II
c. I, II, and IV
d. II and IV
e. III and IV
f. all stay the same
A

a. III

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How would you prepare a 500 mL solution of a 0.25M solution of NaCl?

a. Add 7.3 g NaCl to 500 mL water in a beaker
b. Add 7.3 g NaCl to 500 mL water in a volumetric flask
c. Add 7.3 g NaCl to 500 mL volumetric flask and make the volume up to 500 mL with water.
d. Add 0.25 g NaCl to a 500 mL graduated cylinder and make the volume up to 500 mL with water

A

c. Add 7.3 g NaCl to 500 mL volumetric flask and make the volume up to 500 mL with water.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q 
Which compound can form hydrogen bonds with water but not with itself?
I. CH3OCH3
II. NH2NH2
III. CH3NO2
a. I and II
b. II and III
c. I, II, and III
d. I and III
A

d. I and III

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

The boiling point of ethanol is 352 K. What is true about Gibbs free energy at the boiling point?

a. ΔG is positive
b. ΔG is negative
c. ΔG is equal to zero

A

c. ΔG is equal to zero

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Which compound would be the most soluble in hexane (C6H14)?

a. H2O
b. C8H18
c. CH3OH
d. None are soluble in hexane

A

b. C8H18

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Silver chloride AgCl is insoluble in water. The ΔH for the solution is about zero. Which of these statements must be true?

a. The entropy would increase if Ca3(PO4)2 dissolved in water
b. The entropy would decrease if Ca3(PO4)2 dissolved in water
c. The enthalpy change would increase if the water were heated up
d. The enthalpy change would decrease if the water were heated up

A

b. The entropy would decrease if Ca3(PO4)2 dissolved in water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Why does a solution of sodium chloride conduct electricity, while a solution of sugar does not?
I. Because electrons can flow more easily through a NaCl solution
II. Because sugar molecules are neutral and cannot carry charge to the electrodes
III. Because NaCl ionizes in solution and the ions can carry charge to the electrodes
a. I
b. I and II
c. I, II, and III
d. II and III

A

c. I, II, and III

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

When a salt dissolves in water the temperature of the solution drops. Which of these statements can be inferred from this information?
I. The entropy change for this process is negative
II. The interactions between the species in solution are weaker than those in the separate solute and solvent
III. The interactions between the species in solution are stronger than those in the separate solute and solvent
IV. the entropy change for this process is positive.
a. I
b. I and III
c. II and IV
d. I and II
e. III and IV

A

c. II and IV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why don’t oil and water mix?

a. Because oil is non polar and water is polar
b. The entropy of the system is high in the unmixed state because non-polar molecules cause water molecule to cluster around them
c. There are no attractive forces between oil molecules and water molecules; therefore, the hydrogen bonds between water molecules would require too much energy to break
d. Oil and water repel each other because they both contain negative polar regions

A

b. The entropy of the system is high in the unmixed state because non-polar molecules cause water molecule to cluster around them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

When water boils, what bonds and/or interactions are overcome?

A

Hydrogen bonds, dipole-dipole, LDFs are overcome when water boils

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Explain the mechanism by which energy is transferred at the molecular level during the heating process of water.

A

Bonds are breaking as H2O temp increases which absorbs energy from the surroundings. Energy is transferred through collisions and transfer of quanta. Quanta disperses. Breaking bonds takes energy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the signs of thermodynamic functions for this change:

a. ΔH system
b. ΔH surroundings
c. ΔS system
d. ΔS surroundings
e. ΔG

A

a. ΔH system (+)
b. ΔH surroundings (-)
c. ΔS system (+)
d. ΔS surroundings (-)
e. ΔG (-)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Explain the mechanism by which energy is transferred at the molecular level during the mixing process.

A

Collisions. When atoms collide energy is transferred.

21
Q

The temperature in the beaker increases when LiI and H2O mic, what interactions are being overcome and/or formed?

A

Ionic bonds between LiI are overcome hydrogen bonds, LDFs, and dipole-dipole are over come in H2O. Ionic interactions formed between Li and O and I and H are formed.

22
Q

Using these interactions explain why the temperature increases upon mixing LiI and H2O.

A

Bond making releases heat.
Bond breaking absorbs heat
The interactions that were formed were stronger than the interactions that were overcome.

23
Q

Which do you think is more soluble in water: O2 or He?

a. He because it is smaller and can fit between the water molecules better
b. He because it is small and highly charged and so will attract the water molecules better
c. O2 because it is the right size to fit in the cavities in the water
d. O2 because it is more polarizable and can form stronger interactions with the water molecules

A

d. O2 because it is more polarizable and can form stronger interactions with the water molecules

24
Q

Two toxic substances react to make a new substance. What can you determine about the toxicity level of the new substance?

a. The new substance will be more toxic
b. the new substance would have the same toxicity as the two substances that react
c. The new substances will be harmless
d. You cannot determine if the new substance will be toxic or harmless

A

d. You cannot determine if the new substance will be toxic or harmless

25
Q

What features are always present in a base?
I. The presence of an -OH (hydroxide) group
II. The presence of a lone pair of electrons on the basic atom in the molecule
III. The basic atom in the molecule is highly electronegative
a. I only
b. I and II
c. I and III
d. II and III
e. I, II, and III

A

d. II and III

26
Q

What factors are important when determining the strength of the acid (HX)?
I. The bond strength H-X
II. The entropy change associated with the reaction where HX donates a proton to water
III. The strength of the conjugate base X-
IV. The heat capacity of the acid
a. I and II
b. I and III
c. I, II, and III
d. I, II, III, and IV

A

c. I, II, and III

27
Q

Why in NH4+ a stronger acid than NH3?

a. Because nitrogen is electronegative and can accept electrons
b. Because NH4+ has more protons to donate
c. Because NH4+ has a weaker conjugate base
d. Because NH4+ has a stronger conjugate base

A

c. Because NH4+ has a weaker conjugate base

28
Q

Which is a stronger base in water? CH3O-, or CH3COO-

a. CH3O-, because the negative charge is localized on the oxygen, making the species less stable and therefore a better proton acceptor
b. CH3O-, because the negative charge is de-localized on the oxygen, making the species more stable and therefore less likely to accept a proton
c. CH3COO-, because the negative charge is de-localized over the two oxygens, making the species more stable and therefore less likely to accept a proton
d. CH3COO-, because the negative charge is localized on one of the two oxygens, making the species less stable and therefore a better proton acceptor

A

a. CH3O-, because the negative charge is localized on the oxygen, making the species less stable and therefore a better proton acceptor

29
Q 
Which reaction(s) are redox reaction(s)?
I. CH3Br + -OH -> CH3OH + Br-
II. H+ + H2O -> H3O+
III. H2 + O2 -> H2O
IV. 2 Na + 2H2O -> 2 NaOH + H2
a. I only 
b. I and II
c. III and Iv
d. I, II, and III
A

c. III and IV

30
Q 
If the pH of a 0.01 M solution of a substance is 12.0, what does that tell you about the substance?
I. It is an acid
II. It is a base
III. The substance is completely ionized
IV. The substance is not completely ionized
a. I and III
b. II and III
c. I and IV
d. II and IV
A

b. II and III

31
Q

What is the pH of a 0.50 M solution of HCl?

a. 0.30
b. 0.50
c. 7.0
d. 13.7

A

a. 0.30

32
Q

When a bond between two atoms is broken:

a. Energy is released to the surroundings
b. Energy is absorbed from the surroundings
c. Energy is released or absorbed, depending on the system
d. The energy of the two atom system does not change because energy can neither be created nor destroyed

A

b. Energy is absorbed from the surroundings

33
Q

What mass of Na2CO3 will completely react with 75 mL of 0.20 M HCl? Na2CO3 (aq) + 2 HCl (aq) -> 2 NaCl (aq) + H2CO3 (aq)

a. 0.20 g
b. 0.80 g
c. 1.6 g
d. 7.5 g

A

b. 0.80 g

34
Q 
When pure water is heated, the hydronium ion concentration increase. this means that....
I. The pH increases
II. The pH decreases
III. The water becomes acidic
IV. The water becomes basic 
a. I only
b. II only 
c. I and III
d. I and IV 
e. II and III
f. II and Iv
A

b. II only

35
Q 
What is the enthalpy change for the reaction shown below?
C2H2  + 2H2 -> C2H6
a. -294 kJ/mole
b. +295 kJ/mole
c. -3712 kJ/mole
d. +3712 kJ/mole
A

a. -294 kJ/mole

36
Q 
Given this information below for a reaction A + B -> products, which set of concentrations will allow you to determine the order of reaction with respect to [B]?
[A] = 4; [B] = 4; Initial rate = 2
a. [A] = 2; [B] = 2
b. [A] = 4; [B] = 2
c. [A] = 2; [B] = 4
d. [A] = 1; [B] = 2
A

b. [A] = 4; [B] = 2

37
Q

A reaction A -> B is monitored at constant temperature. You would predict that the rate of reaction at t = 20 s, relative to the rate at t = 0 s, is:

a. Slower, because there are fewer molecules bumping into each other
b. Slower, because the molecules have to get over the activation energy barrier
c. Faster, because the reaction has been given some energy to get over the activation energy barrier at the start
d. Faster, because the molecules gathered momentum

A

a. Slower, because there are fewer molecules bumping into each other

38
Q

The rate equation for a reaction A + B -> product is: rate = k[A]^2[B]. What happens to the rate of the reaction if the concentration of A is doubled and the concentration of B is halved? The temperature is unchanged/

a. The rate halves
b. The rate doubles
c. The rate increases by four
d. The rate stays the same

A

b. The rate doubles

39
Q

A catalyst…
I. Increases the amount of product at equilibrium
II. Shifts the equilibrium state toward the product side
III. Changes the route the reaction takes between reactants and products
a. I only
b. II only
c. III only
d. I and II
e. I and III
f. II and III

A

c. III only

40
Q 
Calculate the equilibrium constant K for the following equilibrium if the concentration of the various components at equilibrium are shown: 
3 F2 (g) + Cl2 (g) -> 2 ClF3 (g)
At equilibrium: [F2(g)] = 2.0 M
[Cl2(g)] = 2.5 M
[ClF3(g)] = 3.0 M
a. 0.45
b. 0.60
c. 1.20
d. 1.80
A

a. 0.45

41
Q

Which of the following statements is always true about any chemical reaction that is at equilibrium?

a. The molecules stop reacting
b. Only side reactions continue; the main reaction stops
c. The amounts of products and reactants are the same at equilibrium
d. The forward and reverse reactions occur at equal rates

A

d. The forward and reverse reactions occur at equal rates

42
Q

What is the pH of a 0.30 M solution of hydrazoic acid, HN3? The Ka of hydrazoic acid is 1.9 x 10^-5?

a. 0.523
b. 1.22
c. 2.62
d. 4.72

A

c. 2.62

43
Q 
The activation energy for the formation of HI(g) from H2(g) and I2(g) is 170 kJ per mole of H2 or I2. The change in enthalpy for the reaction in the forward direction is +50 kJ. 
H2(g) + I2(g) -> 2 HI(g)
ΔH = + 50 kJ
What is the activation energy for the reverse reaction, that is, the decomposition of HI(g) into H2(g) and I2(g)?
a. 25 kJ
b. 50 kJ
c. 120 kJ
d. 170 kJ
e. 220 kJ
A

c. 120 kJ

44
Q

When the reaction A + B -> C + D is at equilibrium, addition of more C will cause the equilibrium position to shift to the left (to product more reactants). Why?

a. Because a stress has been applied to the equilibrium
b. Because the rate of the reverse reaction increases
c. Because of Le Chatelier’s principle
d. Because K decreases when product is added

A

b. Because the rate of the reverse reaction increases

45
Q

A radioactive isotope decomposes via a first-order reaction. What is the half-life (in minutes) of the isotope if 75% of the isotope decomposed in 1.3 hours?

a. 3.1 min
b. 18 min
c. 28 min
d. 39 min
e. 78 min
f. 188 min

A

d. 38 min

46
Q 
Which of the following statements is/are true about a system at equilibrium?
I. The value of ΔG ° tells you the free energy change if all substances are mixed at initial concentrations of 1.0 M at room temperature and atmospheric pressure
II. At equilibrium ΔG ° is equal to zero
III. At equilibrium ΔG  is equal to zero
a. I only 
b. II only
c. II and III
d. I and II
e. I and III
f. I, II, and III
A

e. I and III

47
Q

Why does increasing the temperature affect the rate of a reaction?
I. The frequency of collisions increases, therefore increasing the probability of reaction
II. The energy of collisions increases, therefore more of the collisions transfer enough energy to get over the activation energy barrier
III. The activation energy barrier is lower, thus more reactant molecules have enough energy to get over the activation energy barrier
IV. ΔG becomes more negative, therefore making it more likely that more products will be produced
a. I
b. I and II
c. II and III
d. All of them

A

b I and II

48
Q

For the reaction given below: K BrO-(aq) of HSCN(aq)
Identify the weaker Broasted-Lowry acid in the reaction
a. HBrO
b. SCN-
c. BrO-
d. HSCN

A

a. HBrO

49
Q

Which one of the following substances is the weakest acid?

a. Uric acid, pKa = 3.9
b. Hydrocyanic acid, pKa = 9.2
c. Ascorbic acid, pKa = 4.1
d. Oxalic acid, pKa = 1.2
e. All of the listed acids are the same strength

A

b. Hydrocyanic acid, pKa = 9.2

Chemistry 142 (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions