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- 1. Multiple Choice
Equilibrium for 2CrO42- + 2H+→Cr2O72- + H2O. What happens when OH- ions are added to the system?
Position of equilibrium will shift to right
Color of system will turn from orange to yellow
Kc will decrease
OH- ions will not react, and thus no change is seen.
- 2. Multiple Choice
Given the Kc for a forward reaction, how can you find Kc for the reverse reaction?
Divide Kc by 1
Divide 1 by Kc
Square Kc
Take the square root of Kc
- 3. Multiple Choice
This endothermic reaction is at equilibrium.
If its temperature is increased (at constant volume and pressure), which way will the equilibrium shift?
To products (right)
To reactants (left)
- 4. Multiple ChoiceLe Chatelier's Principle states that if a chemical system at equilibrium is stressed,the system will adjust to increase the stressthe system will adjust to reduce the stressthe system will not adjust
- 5. Multiple ChoiceThis symbol indicates that a reaction is ____________reversibleirreversible
- 6. Multiple ChoiceWhen the rate of the forward reaction is equal to the rate of backward reaction, the system is said to be inChemical EquilibriumChemical BalanceStoichiometryChemical Reaction
- 7. Multiple Choice
For the reaction...
SO2 + O2 <−> SO3
If the concentration of SO2 is increased, the system will shift ___________.
left
right
left and right
neither left nor right
- 8. Multiple Choice
For the reaction...
heat + N2 + O2 ↔ 2NO
If heat is added to the chemical system, the system will shift _______.
left
right
left and right
neither left nor right
- 9. Multiple Choice
2SO2 (g) + O2 (g) ⇌ 2SO3 (g)
Decreasing the volume of container will
shift the system right
shift the system left
change K
have no effect
- 10. Multiple Choice
2SO2 (g) + O2 (g) ⇌ 2SO3 (g)
Using a catalyst will...
shift the system right
shift the system left
increase the rate of reaction
have no effect
- 11. Multiple Choice
At what time (in seconds) is equilibrium established?
0 seconds
1 second
5 seconds
10 seconds
- 12. Multiple ChoiceWhy is equilibrium called a dynamic state?Chemists try to convert as much reactants as possible into products.The reactions at equilibrium continue to take place once equilibrium is established.The products of a forward reaction are favored, so equilibrium lies to the right.All chemical reactions are considered to be reversible under suitable conditions.
- 13. Multiple ChoiceFor the reaction...
N2 + O2 <=> 2NO
If O2 is removed, the concentration of N2 will _______.increasedecreaseremain the samedouble - 14. Multiple ChoiceWhat is the Kc expression for this reaction?
2 NO(g) + O2(g) ⇌ 2 NO2(g)Kc = [NO2]2 / [NO]2 [O2]Kc = [NO]2 [O2] / [NO2]2Kc = [NO]2 [O2] [NO2]2Kc = [NO2]2 / [NO]2 + [O2] - 15. Multiple Choice
Consider the following reaction:
2SO2(g) + O2(g) <=> 2SO3(g) ΔΗ = - 197 kJ
Which of the following will NOT shift the equilibrium position to the right?
Adding more O2
Adding a catalyst
Decreasing the volume
Lowering the temperature
- 16. Multiple ChoiceAn equilibrium constant with a large value, e.g. Kc = 1000, indicates…A very fast reactionMostly products at equilibriumMostly reactants at equilibriumNothing useful at all
- 17. Multiple Choice
When the following reaction reached equilibrium,
SO2 (g) + NO2 (g) <=> SO3 (g) + NO (g)
it was found to contain:
0.40 M SO3 , and 0.30 M NO,
0.15 M NO2 , and 0.20 M SO2.
Calculate the equilibrium constant for this reaction.
4.0
0.42
0.25
1.0
- 18. Multiple Choice
Which is true for a system at equilibrium?
Forward reaction rate is faster than the reverse and concentrations are equal
Forward and reverse reaction rates are equal and concentrations are constant
Forward and reverse reaction rates are equal and concentrations are equal
Forward reaction rate is faster than the reverse and concentrations are constant
- 19. Multiple ChoiceWhat is [H2O] if K = 1.2,
[CO2] = 0.846M, & [CH4]= 0.0713M?
4CuO(s)+CH4(g)↔CO2(g)+4Cu(s) +2H2O(g)0.101 M0.318 M0.0102 M3.77 M - 20. Multiple Choice
What is the correct equilibrium expression for the following reaction:
2H2O2 (aq) ↔ 2H2O (l) + O2 (g)
[H2O]2[O2] / [H2O2]2
[H2O2]2 / [H2O]2[O2]
[O2] / [H2O2]2
[H2O]2 / [H2O2]2
- 21. Multiple Choice
0.40 M SO2 and 0.60 M O2 are in a flask when the following reaction occurs:
2SO2 (g) + O2 (g) ↔ 2SO3 (g)
At equilibrium, the flask is found to contain 0.30 M SO3. Based on these results, the equilibrium constant, Kc, for the reaction is...
20
10
6.7
2.0
- 22. Multiple Choice
Which of the following systems would NOT be shifted by a change in the volume of the system at constant temperature?
CO (g) + NO (g) ↔ CO2 (g) + ½N2 (g)
N2 (g) + 3H2 (g) ↔ 2NH3 (g)
N2 (g) + 2O2 (g) ↔ 2 NO2 (g)
NO(g) + O3 (g) ↔ NO2 (g) + O2 (g)
- 23. Multiple Choice
H2 (g) +I2 (g) ↔ 2HI (g)
All gases begin with an initial concentration of 2.0 M. When equilibrium is established, the concentration of HI is 4.8 M. What is the value of the equilibrium constant?
1.2
2.4
32
64
- 24. Multiple Choice
H2 (g) + I2 (g) ↔ 2HI (g) and Kc = 54.3
If 0.500 mol H2 and 0.500 mol I2 were placed in a 1.00L flask, what would be the concentration of HI at equilibrium?
0.5M
1.0M
3.68M
0.393M
- 25. Multiple Choice
H2C2O4 + 2 H2O ↔ 2 H3O+ + C2O4 2–
Oxalic acid, H2C2O4, is a diprotic acid with
K1 = 5 x 10–2 and K2 = 5 x 10–5.
What is the equilibrium constant for the reaction represented above?
5 x 10–2
5 x 10–5
2.5 x 10–6
5 x 10–7
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