Reaction Mechanisms
what is the molecularity of 2NO(g) + O2(g) --> 2NO2(g)
trimolecular
What is the Kp expression for the following reaction:
K2CO3(s) --> K2O(aq) + CO2(g)
Kp = PCO2
What will happen to the concentration of NO₂ if the temperature is increased?
N2O4(g) ⇌ 2NO2(g) ΔH>0
[NO2] will increase
Label the acid, base, conjugate acid, and conjugate base:
HCl(aq) + NH3(aq) --> Cl-(aq) + NH4+
acid: HCl (strong) conj base: Cl-
base: NH3 (weak) conj acid: NH4+
You have a 0.0010 M HCl solution.
What is the pH and pOH of the solution?
pH = 3.00
pOH = 11.00
Draw a diagram for the following reaction mechanism and label the axis, intermediates, transition states, activation energies, and ΔH.
Step 1 is fast and exothermic
Step 2 is slow and endothermic.
The overall reaction is endothermic
2nd Ea is larger than the first (bigger hump)
intermediate should be lower than reactants and products should be higher than reactants
Fill in an ICE table for the following problem (do not solve the E column):
The concentration-based equilibrium constant for the reaction below is 1.1 × 10−3 at 1300 °C.
Br2(g) ⇌ 2Br(g)
If the initial concentrations are [Br2] = 0.065 M and [Br] = 0.015 M, calculate the concentrations of these two species at equilibrium.
Respectively,
I : 0.065M, 0.015M
C: +x, -2x
E: 0.065+x, 0.015-2x
If the volume of the container decreases, what will happen to the concentration of SO₃?
2SO2(s)+O2(g)⇌2SO3(g)
[SO3] decreases
What is the chemical equation for the reaction that takes place in an aqueous solution of sodium hypochlorite?
OCl-(aq) + H2O(l) ⇋ HOCl(aq) + OH-(aq)
A 0.20 M solution of acetic acid (CH₃COOH) has a pH of 2.72.
Find the Ka of acetic acid.
Ka = 1.8x10-5
Does this mechanism have a catalyst? Does it have an intermediate? How do you know?
H2O2 + I- ⇋ H2O + IO- (fast)
H2O2 + IO- --> H2O + O2 + I- (slow)
IO- is the intermediate and I- is the catalyst.
Explanation:
Intermediates and made then used up (in the inner part of reaction)
Catalysts are used and then made again (because they need to go catalyze other reactions)
The solubility product constant (Ksp) for barium sulfate (BaSO₄) is 1.10 × 10⁻¹⁰ at 25 °C.
What is the molar solubility of BaSO₄ in pure water at 25 °C?
1.05x10-5M
CaCO3(s)⇌CaO(s)+CO2(g) ΔH>0
If additional CaCO₃ is added to the system at equilibrium, what happens to the concentration of CO₂
no change (solids don't affect equilibria)
Given the following list of acids, which one would produce the conjugate base that forms the most basic aqueous solution at equal concentrations?
H2O, NH4+, HCN
H2O
The weakest acid yields the strongest conjugate base
A 0.050 M solution of ammonia (NH₃) has a Ka=5.5x10-10.
Find the pH of the solution.
pH = 10.98
H2O2(aq) + I-(aq) ⇋ H2O(aq) + IO-(aq) (fast)
H2O2(aq) + IO-(aq) --> H2O(l) + O2(aq) + I-(aq) (slow)
overall: 2H2O2(aq) --> 2H2O(l) + O2(aq)
What is the overall rate law?
rate = k[H2O2]2[I-]/[H2O]
k=k2k1/k-1
If the K value for S + O2 ⇌ SO2 is 25 and the K value for A + B ⇌ C is 14, what is the K value for SO2 + 0.5A + 0.5B ⇌ S + O2 + 0.5C
0.15 = K
What effect does removing NaCl have on the equilibrium position of the following reaction:
AgCl(s) ⇌ Ag+(aq) + Cl-(aq)
Equilibrium shifts to the right
Determine each of the following 0.100M solutions, determine whether they will be basic acidic, or neutral:
NaClO, CaCl2, KNO2, and C5H5NHBr
NaClO: basic
CaCl2: neutral
KNO2: basic
C5H5NHBr: acidic
Determine the pH of a 0.25M solution of pyridinium nitrate (C5H6N+ NO3-) at room temperature. Pyridinium has a Kb of 1.7x10-9.
pH = 2.92