Chapter 16
Deriving the rate law from experimental data
For the reaction A + B → C
Experiment | [A] (M) | [B] (M) | Initial Rate (M/s)
1 | 0.10 | 0.10 | 2.0 × 10⁻³
2 | 0.20 | 0.10 | 8.0 × 10⁻³
3 | 0.10 | 0.20 | 2.0 × 10⁻³
a) Find the rate law
b) Determine the value of the rate constant, k
a) Rate = k[A]²
b) k = 0.20 M⁻¹s⁻¹
For the reaction:
N2(g) + 3H2(g) ⇌ 2NH3(g)
Given:
[N2] = 0.40 M, [H2] = 1.20 M, [NH3] = 0.20 M
a) Calculate the reaction quotient, Qc.
b) Given that Kc = 0.15, in what direction does the reaction shift in order to reach equilibrium?
a) 0.058
b) Shift right
Which Arrhenius theory species is an acid?
A) NH3
B) OH-
C) HNO3
D) NaOH
C) HNO3
Reaction rates and stoichiometry
For the reaction
4 NH₃ + 5 O₂ → 4 NO + 6 H₂O
If the rate of formation of NO is 0.80 M/s, find:
a) the rate of disappearance of NH₃
b) the rate of disappearance of O₂
a) 0.80 M/s
b) 1.00 M/s
For the reaction:
H2(g) + I2(g) ⇌ 2HI(g)
Initial concentrations:
H2 = 0.50 M, I2 = 0.50 M, HI = 0.00 M
At equilibrium, [HI] = 0.30 M.
What is the value of Kc?
0.73
At 25°C, what is Kw?
A) 1.0 x 10^-7
B) 1.0 x 10^-14
C) 14
D) 7.0
B) 1.0 x 10^-14
A certain reaction has a rate constant with units of M⁻² s⁻¹.
a) What is the overall reaction order?
b) Write the general form of the rate law.
a) 3rd order
b) rate = k[A]^m[B]^n (m+n=3)
For the reaction:
CO(g) + H2O(g) ⇌ CO2(g) + H2(g)
Initial concentrations:
CO = 0.60 M, H2O = 0.60 M, CO2 = 0.00 M, H2 = 0.00 M
If Kc = 4.0, what is the equilibrium concentration of CO2?
0.40 M
11. A weak acid solution of concentration 0.10 M has a pH of 3.00. What is [H3O+]?
A) 1.0 × 10−3 M
B) 3.0 × 10−3 M
C) 1.0 × 10−1 M
D) 3.0 × 10−2 M
A) 1.0 × 10−3 M
For a first-order process, k = 0.035 min⁻¹. If the starting concentration is 0.750 M, what is [A] after 25.0 minutes?
0.313 M
For the reaction:
2NO2(g) ⇌ N2O4(g) with ΔH < 0
What is the expected shift in equilibrium when:
a) temperature is increased?
b) volume is decreased?
c) more NO2 is added?
a) Left
b) Right
c) Right
A solution has a pH = 5.60. What is [H3O+].
A) 2.5 x 10^-6
B) 4.0 x 10^-6
C) 1.6 x 10^-5
D) 3.2 x 10^-6
A) 2.5 x 10^-6
For a second-order reaction, k = 1.50 M⁻¹ s⁻¹. How long does it take for the concentration to fall from 0.400 M to 0.100 M?
5.0 s
2SO2(g) + O2(g) ⇌ 2SO3(g)
If Kc = 3.5 at 600 K, what is the value of Kp?
Kp = Kc(RT)⁻¹
Which salt, when dissolved in water, will yield a basic solution?
A) NH4Cl
B) NaNO3
C) KBr
D) NaF
D) NaF