Chem exam 2

Which of the following species is amphoteric? a- HPO4^2- b- CO3^2- c- HF d-NH4 e- None of the above are amphoteric

a-HPO4^2-

Which of the following statements is true regarding the Arrhenius equation? a. As the activation energy increases at constant temperature, the rate constant increases. b. As the temperature increases with constant activation energy, the rate constant increases. c. As the rate constant increases, the reaction rate increases. d. To keep the rate constant k constant, as the activation energy must increase as the temperature increases.

a. As the activation energy increases at constant temperature, the rate constant increases.

Which of thse is an example of a polyprotic oxyacid? a. H2SO3 b. HCN c. CH3COOH d. HClO3 e. none of the above

a. H2SO3

Determine the pH of a 0.188 M NH3 solution at 25°C. The Kb of NH3 is 1.76 × 10-5. a. 2.740 b. 5.480 c. 8.520 d. 12.656 e. 11.260

e. 11.260

Write a balanced reaction for which the following rate relationships are true: Rate = -1/2 Δ[N2O5 ]/ Δt = 1/4 Δ[NO 2]/ Δt = Δ[O 2]/ Δt A) 2 N2O5 → 4 NO2 + O2 B) 4 NO2 + O2 → 2 N2O5 C) 2 N2O5 → NO2 + 4 O2 D) 1/4 NO2 + O2 → 1/2 N2O5 E) 1/2 N2O5 → 1/4 NO2 + O2

A) 2 N2O5 → 4 NO2 + O2 reactants are - and products are + take the coefficients

Determine the value of Kc for the following reaction if the equilibrium concentrations are as follows: [N2]eq = 1.5 M, [H2]eq = 1.1 M, [NH3]eq = 0.47 M. N2(g) + 3 H2(g) ↔ 2 NH3(g) A- .11 B- 9.1 C- .78 D- 3.5

A- .11

the combustion of ethylene proceeds by the reaction C2H4 (g) + 3O2 -> 2CO2 (g) + 2H2O (g) When the rate of disappearance is O2 is 0.28M s^-1, the rate of appearance of CO2 is ____________ M s^-1 0.19 0.093 0.84 0.42 0.56

A- 0.19 M s^-1

the rate constant for a first order reaction is 0.54 M-1s-1. What is the half life of this reaction if the initial concentration is 0.27M? A- 1.3s B- 2.0s C- 1.6s D- 0.7s

A- 1.3s

Give the characteristics of a first order reaction having only one reactant A- The rate of the reaction is directly proportional to the concentration of the reactant. B- The rate of the reaction is proportional to the natural logarithm of the concentration of the reactant. C- rate of the reaction is proportional to the square root of the concentration of the reactant. D- The rate of the reaction is not proportional to the concentration of the reactant. E- The rate of the reaction is proportional to the square of the concentration of the reactant.

A- The rate of the reaction is directly proportional to the concentration of the reactant.

Given the following rate law, how does the rate of reaction change if the concentration of Y is doubled? Rate= k[X]^2[Y]^3 A- changes by 8 B- doubles C- changes by 6 D- triples

A- changes by 8

A reaction occurs via the following sequence of elementary steps. What is the rate law based on this mechanism 1st step- A+B-->2C+D Slow 2nd Step- C-->E Fast 3rd Step- D--> 2F Fast A-Rate = k [C]^2[D] B-Rate= k [A] [B] C-Rate= k [E] [F]^2 D-Rate= k [E] E-Rate= k [C]

B- Rate= k[A][B]

Carbon-14 has a half-life of 5720 years and this is a first order reaction. If a piece of wood has converted 75% of the carbon-14, then how old is it? A-1264.3 years B-986 years C-11442 years D-1345.9 years

C- 11442 years

What is the overall order of the following reaction, given the rate law? NO(g) + O3(g) ? NO2(g) + O2(g) Rate = k[NO][O3] A- Step 1 order with respect to NO=1 Step 2 order with respect to O3=3 Step 3 overall order of reaction= 1+3=4 B- Step 1 order with respect to O3=1 Step 2 order with respect to O3=1 Step 3 overall order of reaction= 1 C- Step 1 order with respect to NO =1 Step 2 order with respect to O3=1 Step 3 overall order of reaction =1+1=2 D- Step 1 order with respect to NO= 2 Step 2 order with respect to O3= 1 Step 3 overall order of reaction 1+2=3

C- Step 1 order with respect to NO =1 Step 2 order with respect to O3=1 Step 3 overall order of reaction =1+1=2

An aqueous solution of ammonia is found to be basic. This observation can be explained by the net ionic equation A-NH4+(aq) + H2O(l) → NH3(aq) + H3O+(aq). B-NO3-(aq) + H2O(l) → HNO3(aq) + OH-(aq). C-NH3(aq) + H2O(l) → NH4+(aq) + OH-(aq). D- HNO3(aq) + H2O(l) → NO3-(aq) + H3O+(aq).

C-NH3(aq) + H2O(l) → NH4+(aq) + OH-(aq).

The combustion of ethylene proceeds by the reaction A-C2H4 (g) + O2 -> CO2 (g) +H2O B- C2H4 (g) + H2 -> 2CH2 (g) + 2H2O (g) C- C2H4 (g) -> 2CO2 (g) + 2H2O (g) D-C2H4 (g) + 3O2 -> 2CO2 (g) + 2H2O (g)

D- C2H4 (g) + 3O2 -> 2CO2 (g) + 2H2O (g)

Determine the rate law and the value of k for the following reaction using the data provided. 2 NO(g) + O2(g) --> 2 NO2(g) [NO]i (M) [O2]i (M) Initial Rate (M-1s-1) 0.030 0.0055 8.55 x 10-3 0.030 0.0110 1.71 x 10-2 0.060 0.0055 3.42 x 10-2

K = 1727.27

What is the rate determining step in the reaction? a- slowest b- fastest

a- slowest

What are the products of a reaction of Hydrochloric acid and Sodium hydroxide?

NaOH(aq) + HCl(aq) --> NaCl(aq) + H2O(l)

Find the percent ionization of a 0.337 M HF solution. The Ka for HF is 3.5 × 10-4. a-3.2% b-42% c- 1.4% d-17.4%

a-3.2%

Which of the following is not a conjugate acid base pair? (A).H2SO3/HSO3- (B).H3O+/OH- (C).NH4+/NH3 (D).C2H3O2-/HC2H3O2 (E).All of the above are conjugate acid-base pairs.

b- H3O+/OH-

The chemical equilibrium is the result of? a- The result of the forward reaction being faster than the reverse. b- The result of the forwards and reverse rates converged. c- The result of the reverse reaction being faster than the forward d- The result of the forward and reverse reactions being being equal

b- The result of the forwards and reverse rates converged.

In which of the following reactions will Kc = Kp a) 4NH3(g) + 3O2(g) -----> 2N2(g) + 6H2O(g) b) SO3(g) + NO(g) -----> SO2(g) + NO2(g) c) 2N2(g) + O2(g) -----> 2N2O(g) d) 2SO2(g) + O2(g) ------> 2SO3(g) e) none of the above.

b-SO3(g) + NO(g) --> SO2(g) + NO2(g) must have the same amount of moles on each side

A sample of rainwater has a pH of 3.5. What ion is sure to be present in relatively large concentration in this sample? a. OH- b. H3O+ c. Cl- d. Na+

b. H3O+

Which of the following statements is FALSE? a. The average rate of a reaction decreases during a reaction. b. The half life of a first order reaction is dependent on the initial concentration of reactant. c. It is not possible to determine the rate of a reaction from its balanced equation. d. The rate of zero order reactions are not dependent on concentration. e. None of the statements are FALSE.

b. The half life of a first order reaction is dependent on the initial concentration of reactant

The same number of moles of acetic acid and hydrogen chloride are placed in beakers containing water. After this addition, the beaker with the HCl has more hydronium ions than the beaker with added acetic acid. HCl is classified as a. a weaker acid than acetic acid. b. a stronger acid than acetic acid. c. equal in acid strength to acetic acid. d. a base

b. a stronger acid than acetic acid.

Express the equilibrium constant for following reaction P4(s) + 5O2(g) <-> P4O10(s) a- K= [P4][O2]^5/[P4O10] b- K= [P4O10]/[P4][O2]^5 c- K= [O2]^-5 d- K= [O2]^5

c- K= [O2]^-5

Determine the Ka of an acid whose 0.294 M solution has a pH of 2.80. a-10.1X10^-6 b-7.43X10^-6 c-8.55X10^-6 d-8.0X10^-6

c-8.55X10^-6

A catalyst increases the rate of reaction by_________. a. Decreasing enthalpy b. Decreasing internal energy c. Decreasing activation energy d. Increasing activation energy

c. Decreasing activation energy

All of the following are strong acids except: HCl H3PO4 HBr HClO4 HNO3 a. HCl b. HBr c. H3PO4 d. HCLO4 e. HNO3

c. H3PO4

calculate the hydroxide ion concentration in an aqueous solution with a pH of 4.33 at 25 degrees celsius a-1.6X10^-10 b-2.7X10^-10 c-4.3x10^-10 d-2.1X10^-10

d-2.1X10^-10

The equilibrium constant is given for one of the reactions below. Determine the value of the missing equilibrium constant. H2(g) + Br2(g) ----> 2HBr(g) Kc = 3.8 x 10^4 4HBr(g) ---> 2H2(g) + 2Br1(g) Kc = ? a- 4.7X10^-5 b- 6.2X10^-2 c- 3.8X10^4 d- 5.3X10^-5

d-5.3X10^-5

Sodium hydroxide (NaOH) is classified as a strong base in water. This means it produces: a. No hydroxide ions b. A relatively small fraction of maximum number of possible hydroxide ions c. A relatively large fraction of maximum number of possible hydroxide ions d. 100% of the maximum number of possible hydroxide ions

d. 100% of the maximum number of possible hydroxide ions

A Lewis acid _____? a. Is a proton donor b. Produces H+ ions in water c. Is an electron pair donor d. Is an electron pair acceptor

d. Is an electron pair acceptor

Which of the following statements is false? a. When K >> 1, the forward reaction is favored and essentially goes to completion b. When K << 1, the reverse reaction is favored and the forward reaction does not proceed to great extent c. When K = 1, neither the forward nor the reverse reaction is strongly favored and about the same amount of products and reactants exists at equilibrium d. K >> 1 implies that the reaction is very fast at producing products e. None of the above

d. K >> 1 implies that the reaction is very fast at producing products

Which of the following statements is TRUE? a. The rate constant does not depend on the activation energy for a reaction where the products are lower in energy than the reactants. b. A catalyst raises the activation energy of a reaction. c. The addition of a homogeneous catalyst does not change the activation energy of a given reaction. d. Rate constants are temperature dependent. e. None of the above are true.

d. Rate constants are temperature dependent.

list the characteristics of a strong acid

ionizes completely in an aqueous solution has equilibrium far to the right has a polar bond has a weaker bond to hydrogen