Please help me answer ALL these multiple choice questions. thank you. 1- The for
ID: 927358 • Letter: P
Question
Please help me answer ALL these multiple choice questions. thank you.
1- The formation of rust (Fe2O3) on an exposed piece of metal typically takes several months. Which of the following statements is NOT a reasonable assumption about this chemical reaction? 4Fe(s) + 3O2(g) 2Fe2O3(s)
A) The reaction has a low reaction rate.
B) The reaction has low activation energy.
C) The rusting of iron would occur faster in the warmer summer months than in the cooler winter months.
D) The rusting of iron would occur slower at higher altitudes where the concentration of oxygen is lower.
E) All of the above statements are true about this chemical reaction.
ANSWER: __
2- For the reaction shown below, Keq=2×1011. Which of the following statements concerning this system at equilibrium is true? 2CO(g) + O2(g) 2CO2(g)
A) The equilibrium lies to the left.
B) The equilibrium solution contains equal amounts of CO, O2, and CO2.
C) The reaction is very fast, due to the high value for Keq.
D) The equilibrium solution contains predominantly CO2.
E) The equilibrium system contains almost twice as many reactant molecules as product molecules.
ANSWER: __
3- In the industrial synthesis of ammonia, the equilibrium constant expression may be written as: Keq = [NH3]2 / [N2][H2]3 Calculate the value of this equilibrium constant, if the equilibrium concentration of nitrogen in the reaction mixture at 600°C if [N2] = 4.53 M; [H2] = 2.49 M; and [NH3] = 7.62 M.
A) 5.15
B) 2.07
C) 0.830
D) 0.676
E) 1.44
ANSWER: __
4- A reaction will be spontaneous at all temperatures under which conditions?
A) The reaction is endothermic and accompanied by an increase of disorder.
B) The reaction is endothermic and accompanied by a decrease in disorder.
C) The reaction is exothermic and accompanied by an increase in disorder.
D) The reaction is exothermic and accompanied by a decrease in disorder.
E) The reaction has a positive value for free energy change.
ANSWER: __
5- Which of the following represents an exothermic reaction?
A) A(g) + B(g) 2C(g) H = +100 kcal
B) A(g) B(g) + 33 kcal
C) 50 kcal + 2A(g) C(g) + D(s)
D) Both A and B are exothermic reactions.
E) Both A and C are exothermic reactions.
ANSWER: __
6- Which statement concerning the relative strength of acids is FALSE?
A) Strong and weak acids differ in their extent of proton transfer to water.
B) Strong acids are good proton donors; weak acids are poor proton donors.
C) A strong acid completely transfers its protons to water; a weak acid only partially transfers its protons to water.
D) Strong acids produce strong conjugate bases; weak acids produce weak conjugate bases.
E) A strong acid produces more hydronium ions in water than a weak acid of the same concentration.
ANSWER: __
7- Which of the following correctly describes what is meant by the term neutralization?
A) the gain of electrons to form an uncharged species
B) the loss of electrons to form an uncharged species
C) the reaction between an acid and a base to form salt and water
D) the transfer of electrons from an acid to a base
E) the reaction between an oxidizing agent and a reducing agent
ANSWER: __
8- Consider the following generalized buffer solution equilibrium:
BH+(aq) + H2O(l) <-> H3O+(aq) + B(aq)
When a small amount of a strong base such as sodium hydroxide is added to the solution, which of the four species shown would experience an increase in concentration?
A) BH+
B) H2O
C) H3O+
D) B
E) None of the species would increase in concentration.
ANSWER: __
9- What is true about a solution whose pH is less than 7?
A) It has a hydronium ion concentration less than 1 × 107M.
B) It has a hydronium ion concentration that is higher than pure water itself.
C) It has a hydroxide ion concentration equal to its hydronium ion concentration.
D) It is a solution that requires a buffer.
E) It is a basic solution.
ANSWER: __
10- A particular buffer solution consists of a weak acid and its conjugate base. How could this buffer solution be modified so as to increase its buffer capacity against added base?
A) Increase the concentration of the weak acid.
B) Increase the concentration of its conjugate base.
C) Use a strong base and its conjugate acid instead.
D) Use a strong acid and its conjugate base instead.
E) Make the concentrations of the weak acid and its conjugate base equal.
ANSWER: __
11- The species that remains after an acid donates a proton is called its conjugate base. What is the conjugate base of the hydronium ion, H3O+?
A) OH
B) H2O
C) H2O
D) H2O+
E) H3O+ has no conjugate base.
ANSWER: __
12- Which of the following is an example of a diprotic acid?
A) NH2–
B) H2SO4
C) HCl
D) CH4
E) Both A and B are correct.
ANSWER: __
13- A buffer solution contains carbonic acid (H2CO3) and sodium bicarbonate (NaHCO3), each at a concentration of 0.100 M. The relevant equilibrium is shown below. What is the pH of this buffer solution?
H2CO3(aq) + H2O(l) <-> H3O+(aq) + HCO3- (aq)
Ka = 4.5 × 10-7
A) 4.50
B) 7.00
C) 6.35
D) 7.65
E) 2.16
ANSWER: __
14- What is the general term used to describe what is happening in the half reaction shown below?
F2 + 2e 2F
A) oxidation
B) reduction
C) decomposition
D) combustion
E) Both A and B are correct.
ANSWER: __
15- The reaction A + 2B + C D + 2E is first order in reactant A, first order in B, and second order in C. What is the rate law equation for this reaction?
A) rate = k[A][B][C]2
B) rate = [A][B][C]2
C) rate = [A][B][2C]
D) rate = [A][2B][C]2
E) rate = [A][B]/2[C]
Explanation / Answer
1- The formation of rust (Fe2O3) on an exposed piece of metal typically takes several months. Which of the following statements is NOT a reasonable assumption about this chemical reaction? 4Fe(s) + 3O2(g) 2Fe2O3(s)
A) The reaction has a low reaction rate. TRUE, because it takes months
B) The reaction has low activation energy. True, since it is almost spontaous
C) The rusting of iron would occur faster in the warmer summer months than in the cooler winter months. true, because high temperature helps increase K in the rate constant
D) The rusting of iron would occur slower at higher altitudes where the concentration of oxygen is lower. true, since reactant lowers concnetration, then lowers rate
E) All of the above statements are true about this chemical reaction.
2- For the reaction shown below, Keq=2×1011. Which of the following statements concerning this system at equilibrium is true? 2CO(g) + O2(g) 2CO2(g)
A) The equilibrium lies to the left. since K is very high and positive
B) The equilibrium solution contains equal amounts of CO, O2, and CO2.
C) The reaction is very fast, due to the high value for Keq.
D) The equilibrium solution contains predominantly CO2.
E) The equilibrium system contains almost twice as many reactant molecules as product molecules.
3- In the industrial synthesis of ammonia, the equilibrium constant expression may be written as: Keq = [NH3]2 / [N2][H2]3 Calculate the value of this equilibrium constant, if the equilibrium concentration of nitrogen in the reaction mixture at 600°C if [N2] = 4.53 M; [H2] = 2.49 M; and [NH3] = 7.62 M.
K = (7.62^2)/((4.53)(2.49^3)) = 0.83025920
A) 5.15
B) 2.07
C) 0.830
D) 0.676
E) 1.44
4- A reaction will be spontaneous at all temperatures under which conditions?
G = H - TS and G < 0 ; negative, in order to be true
then
H - TS < 0; only applies
H < TS ... you need a negative H and a positvie S
negative H --> exothermic ... positiv eS --> increase in disorder
A) The reaction is endothermic and accompanied by an increase of disorder.
B) The reaction is endothermic and accompanied by a decrease in disorder.
C) The reaction is exothermic and accompanied by an increase in disorder.
D) The reaction is exothermic and accompanied by a decrease in disorder.
E) The reaction has a positive value for free energy change.
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