Equilibrium Test

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Equilibrium Test - 25

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Weekly Quiz Competition

Question 1
1 / -0

At 1400 K, $$K_c = 2.5 \times 10^{3}$$ for the reaction $$CH_4 (g) + 2H_2S \rightleftharpoons CS_2 (g) + 4H_2 (g)$$. A 10.0 L reaction vessel at 1400 K contains 2.0 mol of $$CH_4$$, 3.0 mol of $$CS_2$$, 3.0 mol of $$H_2$$ and 4.0 mol of $$H_2S$$.The reaction will proceed from right to left to reach equilibrium.

A
True

B
False

C
Ambiguous

D
None of the above

Solution

At 1400 K, $$K_c = 2.5 \times 10^{3}$$ for the reaction $$CH_4 (g) + 2H_2S \rightleftharpoons CS_2 (g) + 4H_2 (g)$$. A 10.0 L reaction vessel at 1400 K contains 2.0 mol of $$CH_4$$, 3.0 mol of $$CS_2$$, 3.0 mol of $$H_2$$ and 4.0 mol of $$H_2S$$.The reaction will proceed from right to left to reach equilibrium.
The reaction quotient $$\displaystyle Q = \frac {[CS_2] [H_2]^2}{[CH_4] [H_2S]^2} $$
$$\displaystyle Q = \frac {3.0 \times (3.0)^2}{2.0 \times (4.0)^2 \times (10)^2} = 0.0084 $$
But the equilibrium constant $$\displaystyle K_c = 2.5 \times 10^3 $$
Hence, the reaction quotient Q is smaller than the equilibrium constant K
$$\displaystyle Q < K$$
Hence, the concentration of products is smaller than the equilibrium concentration and the concentration of reactants is higher than the equilibrium concentration.
The system will shift right to reach equilibrium till Q becomes equal to K.
Question 2
1 / -0

Calculate change in concentration of $${H}^{+}$$ ion in one litre of water,when temperature changes from $$298K$$ to $$310K$$. [Given $${K}_{w}(298)={10}^{-14}, {K}_{w}(310)=2.56\times {10}^{-14}]$$.

A
$$0.3\times {10}^{-7}$$

B
$$0.6\times {10}^{-7}$$

C
$$1.2\times {10}^{-7}$$

D
$$12\times {10}^{-9}$$

Solution

$$K_w = [H^+][OH^-]$$ and $$[H^+] = [OH^-]$$

So at 300 K
$$[H^+] = \sqrt {K_w} = 10^{-7}$$

At 310 K
$$[H^+] = \sqrt {K_w} = 1.6\times10^{-7}$$

So change in conc. of hydrogen ion
$$ [H^+] = 0.6\times10^{-7}$$
Question 3
1 / -0

Assertion: The value of $${K_w}$$ increases with increase in temperature.
Reason: Water dissociates more as temperature increases.

A
Both Assertion and Reason are true and Reason is the correct explanation of Assertion

B
Both Assertion and Reason are true but Reason is not the correct explanation of Assertion

C
Assertion is true but Reason is false

D
Assertion is false but Reason is true

E
Both Assertion and Reason are false

Solution

$$K_w= [H^+][OH^-]$$
As the temperature increases, the dissociation of water increases.
Hence, the hydrogen ion concentration and hydroxide ion concentration increases.
Hence, the value of Kw increases with increase in temperature.
Question 4
1 / -0

Directions For Questions

Amino acid glycine $$(NH_2 CH_2 COOH)$$ exist as a zwitterion in aqueous solution. The $$K_a$$ and $$K_b$$ value of glycine are $$1.6 \times 10^{-10}(pK_a = 9.8)$$ and $$2.5\times 10^{12}(pK_b = 11.6)$$ respectively. The $$K_a$$ and $$K_b$$ values are for zwitterion of amino acid with structure, $$[\overset {\oplus}{N}H_3 CH_3 COO^-]$$.

...view full instructions

What is the $$K_b$$ for $$NH_2$$ group in glycine?

A
$$4\times 10^{-3}$$

B
$$1.6\times 10^{-10}$$

C
$$6.25\times 10^{-5}$$

D
$$2.5\times 10^{-12}$$

Solution

We know,

$$k_b = \dfrac {k_w}{k_a} =\dfrac {1 \times 10^{-14}}{1.6 \times 10^{-10}}=6.25 \times 10^{-5}$$

Hence, the $$K_b$$ for $$NH_2$$ group in glycine is $$6.25 \times 10^{-5}$$.
Question 5
1 / -0

For the reaction $$CO(g) + H_2O \:(g)\rightleftharpoons CO_2 \:(g) + H_2 \:(g)$$ at a given temperature the equilibrium amount of $$CO_2 \:(g)$$ can be increased by :

A
adding a suitable catalyst

B
adding an inert gas

C
decreasing the volume of container

D
increasing the amount of CO (g)

Solution

$$CO(g) + H_2O \:(g)\rightleftharpoons CO_2 \:(g) + H_2 \:(g)$$
so reaction will go to forward direction by adding reactants and go to backward by adding products.
Question 6
1 / -0

$$C_{(s)}+H_2O_{(g)}\rightarrow CO{(g)}+H_2{(g)}$$
The pressure on the system is increased in the above reaction then:

A
$$[H_2O]$$ increase

B
$$[H_2]$$ decrease

C
[CO] decrease,

D
all of the above

Solution

As C is in solid state, any change in its amount will not affect the equilibrium in the gas phase.
Since the number of moles of the products is more than that of the gaseous reactants, increase in pressure will shift the equilibrium towards the left.
So, $$[H_2O]$$ increase, $$[H_2]$$ decrease, $$[CO]$$ decrease,
Question 7
1 / -0

Reaction $$2BaO_2(s)\rightleftharpoons 2BaO(s) + O_2 \: (g) \: ; \: \Delta H= + ve$$. At equilibrium condition, Pressure of $$O_2$$ is depends on :

A
Increase mass of $$BaO_2$$

B
Increase mass of BaO

C
Increase temp. at $$Eq^m$$.

D
Increase mass of $$BaO_2$$ and BaO both

Solution

$$K_p=P_{O_2}$$
Hence, pure solids of added do not change state of equilibrium.
Only a change in temperature changes $$K_p$$ hence $$P_{O_2}$$ will be affected by increasing temperature.
Hence, option C is correct.
Question 8
1 / -0

Listed in the table are forward and reverse rate constants for the reaction $$2NO (g) \rightleftharpoons N_2 (g) + O_2 (g)$$.

Temperature (K)
$$k_f(M^{-1}s^{-1})$$
$$k_r(M^{-1}s^{-1})$$
1400
0.29
$$1.1\times 10^{-6}$$
1500
1.3
$$1.4\times 10^{-5}$$

Is the reaction endothermic or exothermic?

A
Exothermic reaction

B
Endothermic reaction

C
Can't predict

D
None of these

Solution

At 1400 K,

$$\displaystyle K = \frac {K_f}{K_r} = \frac {0.29}{1.1 \times 10^{-6}} = 2.64 \times 10^5 $$

At 1500 K,

$$\displaystyle K = \frac {K_f}{K_r} = \frac {1.3}{1.4 \times 10^{-5}} = 9.29 \times 10^4 $$

Thus, with an increase in temperature, the value of the equilibrium constant decreases. Hence, the reaction is exothermic.
Question 9
1 / -0

An equimolar solution of $${NaNO_2}$$ and $${HNO_2}$$ can act as a:

A
strong reductant

B
strong oxidant

C
buffer solution

D
none of these

Solution

$${HNO_2}$$ is a weak acid.
$${NaNO_2}$$ is a salt of weak acid $${HNO_2}$$ with strong base $$NaOH$$.
Hence, an equimolar solution of $${HNO_2}$$ and $${NaNO_2}$$ acts as a buffer solution.
Question 10
1 / -0

The ionization constant of water is related to ionic product as:

A
$${k_w>k\left [ H_2O \right ]}$$

B
$${k_w=k\left [ H_2O \right ]}$$

C
$${k_w<\left [ H_2O \right ]}$$

D
none of the above

Solution

The ionization constant of water is related to ionic product by the expression $${k_w=k\left [ H_2O \right ]}$$.
The ionization constant for water is given by the expression $$K= \frac {[H^+][OH^-]}{[H_2O]}$$.
Hence, $$K[H_2O] = [H^+][OH^-]$$
The ionic product of water is given by the expression $$K_w=[H^+][OH^-]$$.
Hence, $${k_w=k\left [ H_2O \right ]}$$.

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Re-Attempt Weekly Quiz Competition

Temperature (K)	$$k_f(M^{-1}s^{-1})$$	$$k_r(M^{-1}s^{-1})$$
1400	0.29	$$1.1\times 10^{-6}$$
1500	1.3	$$1.4\times 10^{-5}$$

Equilibrium Test - 25

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Equilibrium Test - 25

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Question 1

True

False

Ambiguous

None of the above

Solution

Question 2

$$0.3\times {10}^{-7}$$

$$0.6\times {10}^{-7}$$

$$1.2\times {10}^{-7}$$

$$12\times {10}^{-9}$$

Solution

Question 3

Both Assertion and Reason are true and Reason is the correct explanation of Assertion

Both Assertion and Reason are true but Reason is not the correct explanation of Assertion

Assertion is true but Reason is false

Assertion is false but Reason is true

Both Assertion and Reason are false

Solution

Question 4

$$4\times 10^{-3}$$

$$1.6\times 10^{-10}$$

$$6.25\times 10^{-5}$$

$$2.5\times 10^{-12}$$

Solution

Question 5

adding a suitable catalyst

adding an inert gas

decreasing the volume of container

increasing the amount of CO (g)

Solution

Question 6

$$[H_2O]$$ increase

$$[H_2]$$ decrease

[CO] decrease,

all of the above

Solution

Question 7

Increase mass of $$BaO_2$$

Increase mass of BaO

Increase temp. at $$Eq^m$$.

Increase mass of $$BaO_2$$ and BaO both

Solution

Question 8

Exothermic reaction

Endothermic reaction

Can't predict

None of these

Solution

Question 9

strong reductant

strong oxidant

buffer solution

none of these

Solution

Question 10

$${k_w>k\left [ H_2O \right ]}$$

$${k_w=k\left [ H_2O \right ]}$$

$${k_w<\left [ H_2O \right ]}$$

none of the above

Solution

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