Equilibrium Test

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Equilibrium Test - 26

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Question 1
1 / -0

For the reaction $${{\text{H}}_{\text{2}}}{\text{(g) + }}{{\text{I}}_{\text{2}}}{\text{(g)}} \rightleftharpoons {\text{2HI(g)}}$$
$$\rm{K_c}=66.9$$ at $$350^\circ$$C and $$\rm{K_c}=50.0$$ at $$448^\circ$$C. The reaction has:

A
$$\Delta H= +ve$$

B
$$\Delta H= -ve$$

C
$$\Delta H= Zero$$

D
$$\Delta H=$$ Not found the signs

Solution

As temp. increases, eqm constant value decreases so its an exothermic reaction and $$\Delta H= -ve$$. (Refer table)

Hence, the correct option is B
Question 2
1 / -0

Given the following reaction at equilibrium $$N_2 \:(g) + 3H_2 \:(g)\rightleftharpoons 2 NH_3 \:(g)$$. Some inert gas at constant pressure is added to the system. Predict which of the following facts will be affected :

A
more $$NH_3 \:(g)$$ is produced

B
less $$NH_3 \:(g)$$ is produced

C
no affect on the equilibrium

D
$$K_P$$ of the reaction is decreased

Solution

When an inert gas is added to the equilibrium mixture at constant pressure, the equilibrium will shift in the direction in which there is increase in the number of moles of gas. In the reaction for the formation of ammonia, the number of moles of gaseous reactants are greater than the number of moles of gaseous products. Hence, when inert gas is added, the equilibrium will shift in the reverse direction. Hence, less ammonia is obtained.
Question 3
1 / -0

A reaction in equilibrium is represented by the following equation.

$$2{A}_{(s)}+3{B}_{(g)}\rightleftharpoons 3{C}_{(g)}+{D}_{(g)}+Q$$

If the pressure on the system is reduced to half of its original value:

A
The amounts of C and D decreases

B
The amounts of C and D increases

C
The amount of D decreases

D
All the amounts remain constant

Solution

When a system at equilibrium undergoes a change in pressure, the equilibrium of the system will shift to offset the change and establish a new equilibrium. The system can shift in one of two ways:
-Toward the reactants (i.e. in favor of the reverse reaction)
-Toward the products (i.e. in favor of the forward reaction)
The effects of changes in pressure can be described as follows (this only applies to reactions involving gases):
-When there is an increase in pressure, the equilibrium will shift towards the side of the reaction with fewer moles of gas.
-When there is a decrease in pressure, the equilibrium will shift towards the side of the reaction with more moles of gas.
$$2{A}_{(s)}+3{B}_{(g)}\rightleftharpoons 3{C}_{(g)}+{D}_{(g)}+Q$$ if the pressure on the system is reduced to half of its original value, the amounts of C and D increases as product side has more moles of gases.
Question 4
1 / -0

In a 20 litre vessel, initially 1 mole each of $$CO,\ {H}_{2}O,\ C{O}_{2}$$ is present, then for the equilibirum of
$$CO+{H}_{2}O\rightleftharpoons C{O}_{2}+{H}_{2}$$, which one among the following is true?

A
$${H}_{2}$$ is more than 1 mole

B
$$CO,\ {H}_{2}O,\ H_{2}$$ each are less then 1 mole

C
$$C{O}_{2},{H}_{2}O$$ both are more than 1 mole

D
All of these

Solution

$$\underset {1}{CO}\ +\underset {1}{H_2O}\rightleftharpoons \underset {1}{CO_2}+\ \underset{0}{H_2}$$

$$\underset {1-x}{CO}\ +\underset {1-x}{H_2O}\rightleftharpoons \underset {1+x}{CO_2}+\ \underset{x}{H_2}$$

At equilibrium, the reaction won't go to completion. Hence $$x<1$$

So, $$CO$$, $$H_2O$$ and $$H_2$$ will be less than 1 mole.

Hence, option B is correct
Question 5
1 / -0

When add 0.01 M HCl in aqueous solution of acetic acid :

A
$$C{H}_{3}CO{O}^{-}$$ molar conc. is decrease

B
$$C{H}_{3}COOH$$ molar conc. is decrease

C
$$C{H}_{3}CO{O}^{-}$$ molar conc. is increase

D
None of these

Solution

When we add 0.01 M HCl in aqueous solution of acetic acid, it will react

$$CH_3COO^- + HCl \rightarrow CH_3COOH + Cl^-$$

As a result, $$C{H}_{3}CO{O}^{-}$$ molar conc. decreases and conc. of acetic acid increases.
Question 6
1 / -0

Which of the following is correct regarding buffer solution?

A
It contains weak acid and its conjugate base.

B
It shows low change in pH on adding small amount of acid or base.

C
(A) and (B) both

D
None of these

Solution

A buffer solution (more precisely, pH buffer or hydrogen ion buffer) is an aqueous solution consisting of a mixture of a weak acid and its conjugate base, or vice versa. Its pH changes very little when a small or moderate amount of strong acid or base is added to it and thus it is used to prevent changes in the pH of a solution. Buffer solutions are used as a means of keeping pH at a nearly constant value in a wide variety of chemical applications.
Question 7
1 / -0

For the reaction $$A+2B\rightleftharpoons 2C+D$$, initial concentration of A is a and that of B is 1.5 times that of A. Concentration of A and D are same at equilibrium. What should be the concentration of B at equilibrium?

A
$$\displaystyle\frac{a}{4}$$

B
$$\displaystyle\frac{a}{2}$$

C
$$\displaystyle\frac{3a}{4}$$

D
All of the above

Solution

Let x be the change in the concentration of A to reach equilibrium.
A B C D
Initial concentration
a
1.5a
0
0
Equilibrium concentration
$$a-x$$ $$1.5a-2x$$
$$2x$$
$$x$$
Concentration of A and D are same at equilibrium.
$$\displaystyle a-x = x$$
$$\displaystyle a = 2x$$
$$\displaystyle x = 0.5$$
The equilibrium concentration of B is $$\displaystyle 1.5a-2x = 1.5a - a = \frac {a}{2} $$.

Question 8

1 / -0

As pressure is increased, what will happen to the following reactions?

Match the column:

Column - I	Column - II
(P) $$PCl_5(g)\rightleftharpoons PCl_3(g)+Cl_2(g)$$	(1) Shift to forward
(Q) $$2NO_2(g)\rightleftharpoons N_2O_4(g)$$	(2) Shift to backward
(R) $$H_2(g)+I_2(g)\rightleftharpoons 2HI(g)$$	(3) No effect
(S) $$aA(g)+bB(g)\rightleftharpoons cC(g)$$	(4) Cannot predict

1 2 3 4

2 1 3 4

2 1 4 3

4 3 1 2

Solution

An increase in pressure will cause the reaction to shift in the direction that reduces pressure, that is the side with the fewer number of gas molecules.

For reaction (P), the equilibrium will shift to backward as number of moles of gaseous reactants is less than the number of moles of gaseous products.

For reaction (Q), the equilibrium will shift to forward as number of moles of gaseous reactants is more than the number of moles of gaseous products.

For reaction (R), the equilibrium will not shift in any direction as number of moles of gaseous reactants is equal to the number of moles of gaseous products.

For reaction (S), the direction of the shift in the equilibrium cannot be predicted as number of moles of gaseous reactants and gaseous products is not given.

Question 9
1 / -0

Identify the correct option amongst the following:
Electropositive atoms tend to form :

A
negative ions

B
positive ions

C
covalent bonds

D
metallic bonds

Solution

Electropositive elements tend to lose electrons and form positive ions e.g. univalent alkali metals$${ Li }^{ + },{ Na }^{ + },{ K }^{ + }$$and divalent alkaline earth metals $$ { Be }^{ 2+ },{ Mg }^{ 2+ }$$
Question 10
1 / -0

Which of the following can give a buffer solution?

A
$$HCI + NaOH$$

B
$$CH$$$$_3$$$$COONa$$

C
$$HCOOH + HCOONa$$

D
$$H_2SO_4 + Na_2SO_4$$

Solution

Buffer solutions have reserve acidity and reserve basicity. They are a mixture of a weak acid and its salt with a strong base or weak base and its salt with strong acid.
$$\therefore$$ $$HCOOH$$ and $$HCOONa$$ can from a buffer.

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	A	B	C	D
Initial concentration	a	1.5a	0	0
Equilibrium concentration	$$a-x$$	$$1.5a-2x$$	$$2x$$	$$x$$

Equilibrium Test - 26

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Equilibrium Test - 26

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Question 1

$$\Delta H= +ve$$

$$\Delta H= -ve$$

$$\Delta H= Zero$$

$$\Delta H=$$ Not found the signs

Solution

Question 2

more $$NH_3 \:(g)$$ is produced

less $$NH_3 \:(g)$$ is produced

no affect on the equilibrium

$$K_P$$ of the reaction is decreased

Solution

Question 3

The amounts of C and D decreases

The amounts of C and D increases

The amount of D decreases

All the amounts remain constant

Solution

Question 4

$${H}_{2}$$ is more than 1 mole

$$CO,\ {H}_{2}O,\ H_{2}$$ each are less then 1 mole

$$C{O}_{2},{H}_{2}O$$ both are more than 1 mole

All of these

Solution

Question 5

$$C{H}_{3}CO{O}^{-}$$ molar conc. is decrease

$$C{H}_{3}COOH$$ molar conc. is decrease

$$C{H}_{3}CO{O}^{-}$$ molar conc. is increase

None of these

Solution

Question 6

It contains weak acid and its conjugate base.

It shows low change in pH on adding small amount of acid or base.

(A) and (B) both

None of these

Solution

Question 7

$$\displaystyle\frac{a}{4}$$

$$\displaystyle\frac{a}{2}$$

$$\displaystyle\frac{3a}{4}$$

All of the above

Solution

Question 8

1 2 3 4

2 1 3 4

2 1 4 3

4 3 1 2

Solution

Question 9

negative ions

positive ions

covalent bonds

metallic bonds

Solution

Question 10

$$HCI + NaOH$$

$$CH$$$$_3$$$$COONa$$

$$HCOOH + HCOONa$$

$$H_2SO_4 + Na_2SO_4$$

Solution

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