Unit 9 – Chemical Equilibrium

Question 1 of 13

1. Question

The characteristics of reversible reactions are the following except:

products never recombine to form reactants
they never complete
they proceed in both ways
they have a double arrow between reactants and products

Question 2 of 13

2. Question

In the lime kiln, the reaction C_aCO₃(s) → C_a0(s) + C0₂(g) goes to completion because

of high temperature
C_aO is more stable than C_aCO₃
CO₂ escapes continuously
C_aO is not dissociated

Question 3 of 13

3. Question

For the reaction, 2A_(g) + B_(g)⇌ 3c_(g) the expression for the equilibrium constant is:

[2A][B] / [3C]
[A]²[B] / [C]³
[3C][2A] / [B]
[C]³ / [A]²[B]

Question 4 of 13

4. Question

When a system is at equilibrium states

the concentration of reactants and products becomes equal
the opposing reactions (forward and reverse) stop
the rate of the reverse reaction becomes very low
the rates of the forward and reverse reactions become equal

Question 5 of 13

5. Question

Which one of the following statement is not correct about active mass?

rate of reaction is directly proportional to active mass
active mass is taken in molar concentration
active mass is represented by square brackets
active mass means total mass of substances

Question 6 of 13

6. Question

When the magnitude of K is very large it indicates

reaction mixture consists of almost all products
reaction mixture has almost all reactants
reaction has not gone to completion
reaction mixture has negligible products

Question 7 of 13

7. Question

When the magnitude of K is very small it indicates

equilibrium will never establish
all reactants will be converted to products
reaction will go to completion
the amount of-products is negligible

Question 8 of 13

8. Question

Reactions which have comparable amounts of reactants and products at equilibrium state have

very small K_c value
very large K_c value
moderate K_c value
none of these

Question 9 of 13

9. Question

At dynamic equilibrium

the reaction stops to proceed
the amounts of reactants and products are equal
the speeds of the forward and reverse reactions are equal
the reaction can no longer be reversed

Question 10 of 13

10. Question

In an irreversible reaction dynamic equilibrium

never establishes
establishes before the completion of reaction
establishes after the completion of reaction
establishes readily

Question 11 of 13

11. Question

A reverse reaction is one that

which proceeds from left to right
in which reactants react to form products
which slows down gradually
which speeds up gradually

Question 12 of 13

12. Question

Nitrogen and hydrogen were reacted together to make ammonia;
N_{2 +}3H₂ ⇌ 2NH₃ K_C = 2.86 mol^-2 dm⁶

What will be present in the equilibrium mixture?

NH₃ only
N₂,H₂ & NH₃
N₂ & H₂
H_{2 only}

Question 13 of 13

13. Question

For a reaction between PCl₃ and Cl₂ to form PCl₅, the units of K_c, are:

mol dm^-3
mol^-1dm^-3
mol^-1dm³
mol dm³