WorksheetsChemical Equilibrium and Acids/Bases Midterm Exam-3
Total questions: 28
Worksheet time: 1hrs 2mins
What is the equilibrium constant expression for the reaction below?
2 CaSO4(s) <---> 2 CaO(s) + 2 SO2(g) + O2(g)
Kc = [CaO]/[CaSO4]
Kc = [CaO]2[SO2]2[O2]/[CaSO4]2
Kc = [SO2]2[O2]
Kc = [SO2][O2]
When Kc >> 1 for a chemical reaction:
the equilibrium would be achieved rapidly.
reactants would be much more stable than products.
product concentrations would be much greater than reactant concentrations at equilibrium.
reactant concentrations would be much greater than product concentrations at equilibrium.
Given: N2(g) + 3 H2(g) <---> 2 NH3(g)
At equilibrium at a certain temperature, the concentration of NH3(g), H2(g) and N2(g) are 0.980 M, 1.89 M and 0.510 M, respectively. Calculate the value of Kc for this reaction.
0.279
0.837
0.16
0.526
In the gas phase reaction:
PCl3(g) + Cl2(g) <-----> PCl5(g)
Kc = 1.9
the system is in equilibrium with concentrations [PCl3] = 0.5 M and [Cl2] = 0.8 M. What is the PCl5 concentration?
0.76 M
2.1 M
1.9 M
0.54 M
The pressure of CO2 is 0.227 atm. Calculate Kc of the reaction at 25oC.
CaCO3 (s) ⇌ CaO (s) + CO2 (g)
7.9 x 10-2
9.3 x 10-3
5.8 x 10-4
10.1 x 10-6
What is Kp value for the following reaction if Kc = 2.12 at 58oC?
H2 (g) + ½ O2 ⇌ H2O (g)
0.203
0.407
1.89
1.34
The value of the equilibrium constant for the reaction:
2 HBr(g) <----> H2(g) + Br2(g) is
Kc = 1.26 x 10-12 at 500 K. This implies that:
the product concentrations will be large relative to the reactants at equilibrium.
the reactants are much more thermodynamically stable than the products.
the reaction has a large negative ΔG°.
the rate of this reaction is very slow.
The reaction: 2 SO2(g) + O2(g) <---> 2 SO3(g)
has come to equilibrium in a vessel of specific volume and at a given temperature. Before the reaction, the concentrations of the reactants were 0.060 M of SO2 and 0.050 M of O2. No SO3 was present. After equilibrium was reached, the concentration of SO3 was 0.040 M. What is the equilibrium constant Kc for this reaction?
13.33
133
4.0
8.9
What would be the effect of decreasing the pressure by increasing the volume on the following system at equilibrium?
2 CO(g) + O2 <---> 2 CO2(g)
The equilibrium would be perturbed and would show a net shift to the left.
There would be no effect. The system is at equilibrium.
The equilibrium would be perturbed and would show a net shift to the right.
2 NO2(g) <---> 2 NO(g) + O2(g)
If additional O2 is added to a vessel at equilibrium what will ultimately happen to the NO2 concentration?
it will increase
it will decrease
it will remain the same
2 NO2(g) <---> 2 NO(g) + O2(g)
The reaction is endothermic. What will happen to the NO2(g) concentration if the temperature is increased?
it will increase
it will decrease
it will remain the same
A large equilibrium constant
indicates that the reaction favors the formation of reactants.
indicates that the reaction favors the formation of products.
results from the addition of a catalyst to a reaction mixture.
indicates that a reaction has a large rate constant.
Consider the following reaction:
4 PCl3(g) --> P4(g) + 6 Cl2(g)
If the initial concentration of PCl3(g) is 1.0 M, and "x" is the equilibrium concentration of P4(g), what is the correct equilibrium relation?
Kc = 6x7
Kc = (x)(6x) 6/(1.0 - 4x)4
Kc = x7/(1.0 - x)4
Kc = 6x7/(1.0 - 4x)4
Which of the following changes can affect the value of the equilibrium constant?
introducing a catalyst
changing the concentrations of species
changing the temperature inside the reaction vessel
changing the initial concentrations of species
A collection of gases N2(g), Cl2(g) and NCl3(g) are in equilibrium in a reaction vessel.
N2(g) + 3 Cl2(g) <-----> 2 NCl3(g)
Suddenly the vessel size is compressed to half its volume. What will happen?
The equilibrium constant will get larger.
Nothing will change. The system is at equilibrium.
The system will no longer be in equilibrium and more product will form as equilibrium is restored.
The system will no longer be in equilibrium and more reactants will form as equilibrium is restored.
Which of the following properties are NOT consistent with acids?
have a sour taste
have a slippery feeling
change blue litmus to red
produces H+ (or H3O+) ions in aqueous solution
In the Lowry-Bronsted theory a base is:
a proton donor
a proton acceptor
Calculate the pH of 3.0 M NaOH(aq) solution.
13.477
11.0
14.47
3.0
Calculate the hydroxide concentration in 1.0 M HNO3(aq).
13.0 M
1.0 x 10-14 M
1.0 M
1.0 x 10-7 M
The molar concentration of the OH- ion is __________ in 0.022 M calcium hydroxide.
0.044 M
0.030 M
0.015 M
Which of the following does NOT completely ionize in aqueous solution?
HNO3
HCl
HClO4
HF
Which salt is produced from a STRONG acid and a WEAK base?
LiF
NaHCO3
NH4NO3
NaHSO4
Rank the hydrohalic acids from strongest to weakest:
HF > HCl > HBr > HI
HCl > HBr > HI > HF
HI > HBr > HCl > HF
According to the Lewis theory, a base:
accepts a share in a pair of electrons.
makes available a share in a pair of electrons.
is a proton donor.
is a proton acceptor.
The following acids are listed in order of decreasing acid strength in water. According to the Brønsted-Lowry theory, which one of the following anions is the weakest base?
HI > HNO2 > CH3COOH > HCN
NO2-
CH3COO-
I-
CN-
Which one of the following pairs of acids is INCORRECTLY listed?
(Stronger Acid; Weaker Acid)
HClO; HClO2
H2SO3; H2SeO3
HNO3; HNO2
H2SO4; H2SO3
Identify the INCORRECT statement:
As the pH increases the hydronium ion concentration decreases.
As the pH increases the hydroxide ion decreases.
As the pH increases the solution becomes less acidic and more alkaline.
As the pH increases the Kw of water remains the same.
What is the pH of a 0.030 M solution of morphine (C7H19NO3) at 25oC if
Kb = 1.6 x 10-6?
10.34
10.09
12
7.22
