Equilibrium Test

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Equilibrium Test - 30

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Weekly Quiz Competition

Question 1
1 / -0

For the reaction $${ I }_{ 2 }(g)+{ H }_{ 2 }(g)\rightleftharpoons 2HI(g)$$,
what is the effect on the equilibrium position when the pressure of the reaction vessel is increased?

A
Increased production of products

B
Increased production of reactants

C
Fluctuations in the amounts of reactants and products

D
No impact on the equilibrium

E
Cannot be determined

Solution

If there are the same number of moles of gas in reagents and products, changing pressure or volume has no effect on the reaction.
Question 2
1 / -0

Degree of ionisation does not depend on:

A
nature of the solvent

B
nature of the electrolyte

C
dilution

D
molecular mass of the electrolyte

Solution

Degree of ionization $$(\alpha)$$ depends on-
1) Concentration of solute
2) Temperature
3) Nature of electrolysis
4) Nature of solvent
5) Dilution
"$$\alpha$$" does not depend on molecular mass of electrolyte.
Question 3
1 / -0

Dissociation events in $$H_2O \rightarrow H^+ +OH^-$$ is termed as ionization because :

A
the electron is initially shared between both atoms, thus the dissociation event into ions involves the transfer of an electron from one atom to the other

B
it does not involve any electron transfer

C
charged species formed

D
no charge species formed

Solution

$$H_2O\longrightarrow H^++OH^-$$
This dissociation is termed as ionization because initially there is a polar covalent compound $$H_2O$$.
This dissociation leads to the formation of ions $$H^+$$ and $$OH^-$$
This dissociation involves a transfer of an electron from one atom to another leading to the formation of charged species.
Question 4
1 / -0

Which of the following will not function as a buffer solution?

$$(i)$$ $$NaCl$$ and $$NaOH$$
$$(ii)$$ $$NaOH$$ and $${NH}_{4}OH$$
$$(iii)$$ $${CH}_{3}COO{NH}_{4}$$ and $$HCl$$
$$(iv)$$ Borax and boric acid

A
$$(i),(ii),(iii)$$

B
$$(ii),(iii),(iv)$$

C
$$(i),(iii),(iv)$$

D
$$(i),(ii),(iii),(iv)$$

Solution

A buffer solution is a salt of either weak acid and its salt with a strong base ($$AcOH + NaOAc$$) or a weak base and its salt with a strong acid ($$NH_3+NH_4Cl$$).

(i) $$NaCl$$ and $$NaOH$$ consists of salt of strong acid and strong base.

(ii) $$NaOH$$ and $$NH_4OH$$ consists of a weak base and strong base.

(iii) $$CH_3COONH_4$$ and $$HCl$$ consists of strong acid and a salt.

(iv) Borax and boric acid is an acid buffer solution. It consists of a weak acid (boric acid) and it's salt (borax) with a strong base.

Hence, option A is correct.
Question 5
1 / -0

The state of equilibrium refers to:

A
State of rest

B
Dynamic state

C
Stationary state

D
State of inertness

Solution

The state of equilibrium refers to dynamic state. Both forward and backward reactions proceed in the opposite directions with equal rates. Neither the forward reaction nor the backward reaction has ceased.
Question 6
1 / -0

How many grams of ammonium chloride should be dissolved in 500 mL of water to have a solution of pH 4.5?

[$$\displaystyle K_b$$ for ammonium hydroxide is $$ \displaystyle1.8 \times 10^{-5}$$]

A
25.22

B
48.15

C
53.5

D
90

Solution

$$\displaystyle [H^+]=10^{-pH}=10^{-4.5}=3.162 \times 10^{-5} mol/L$$
$$\displaystyle [H^+]=\sqrt {\dfrac {K_wC}{K_b}}$$
$$\displaystyle C = \dfrac {[H^+]^2K_b}{K_w}$$
$$\displaystyle C = \dfrac {3.162 \times 10^{-5} \times 3.162 \times 10^{-5} \times 1.8 \times 10^{-5}}{1 \times 10^{-14}}=1.8 \: mol/L$$
Number of moles of ammonium chloride present in 500 mL $$\displaystyle = \dfrac {1.8 \times 500}{1000}=0.9$$ moles.
The molar mass of ammonium chloride is 53.5 g/mol. The mass of ammonium chloride will be $$\displaystyle 0.90 \times 53.5 = 48.15 $$ g
Question 7
1 / -0

Consider the reactions,
(i) $$P{ Cl }_{ 5 }(g)\rightleftharpoons P{ Cl }_{ 3 }(g)+{ Cl }_{ 2 }(g)$$
(ii) $${ N }_{ 2 }{ O }_{ 4 }(g)\rightleftharpoons 2{ NO }_{ 2 }(g)$$
The addition of an inert gas at constant volume:

A
will increase the dissociation of $$P{ Cl }_{ 5 }$$ as well as $${ N }_{ 2 }{ O }_{ 4 }$$

B
will reduce the dissociation of $$P{ Cl }_{ 5 }$$ as well as $${ N }_{ 2 }{ O }_{ 4 }$$

C
will increase the dissociation of $$P{Cl}_{5}$$ and step up the formation of $${NO}_{2}$$

D
will not disturb the equilibrium of the reaction

Solution

If insert gas is added at constant volume it will not disturb the equilibrium of the reaction as it will not react with any of the reactant or product species.
Question 8
1 / -0

For the reaction, $$P{ Cl }_{ 5 }(g)\rightleftharpoons P{ Cl }_{ 3 }(g)+{ Cl }_{ 2 }(g)$$, the position of equilibrium can be shifted to the right by:

A
doubling the volume

B
increasing the temperature

C
addition of equimolar quantities of $$P{Cl}_{3}$$ and $$P{Cl}_{5}$$

D
addition of $${Cl}_{2}$$ at constant volume

Solution

$$Le Chatelier’s principle$$ states that changes in the temperature, pressure, volume or concentration of a system will result in predictable and opposing changes in the system in order to achieve a new equilibrium state.
If the reaction is endothermic, an increase in temperature will cause the forward reaction to occur, increasing the amounts of the products, and decreasing the amounts of reactants.
In an exothermic reaction, if you increase the temperature, then the number of products increases, and so you shift the balance at equilibrium back toward reactants, meaning there will be more reactants left at equilibrium.
since
$$PCl_5(g)\rightleftharpoons PCl_3(g)+Cl_2(g)$$ is endothermic reaction the position of the equilibrium shift towards right.
Hence the correct answer is option $$B$$.
Question 9
1 / -0

Densities of diamond and graphite are $$3.5$$ and $$2.3$$ $$g/mL$$ respectively. Increase in pressure on the equilibrium
$${ C }_{ diamond }\rightleftharpoons { C }_{ graphite }$$:

A
Favours backward

B
Favours forward reaction

C
Has no effect

D
Increases the reaction rate

Solution

Densities of diamond and graphite are $$3.5$$ and $$2.3$$ $$g/mL$$ respectively. Increase in pressure on the equilibrium favours backward.
$${ C }_{ diamond }\rightleftharpoons { C }_{ graphite }$$
When pressure is increased, the equilibrium will shift towards reverse direction. It is the direction that has higher density. Higher density means lower volume for a fixed mass of water.
Thus, increase in pressure will shift equilibrium towards lower volume.
Question 10
1 / -0

For the reaction,
$$2A(g)+B(g)\rightleftharpoons 3C(g)+D(g)$$
two moles each of $$A$$ and $$B$$ were taken into a flask. The following must always be true when the system attained equilibrium:

A
$$\left[ A \right] =\left[ B \right] $$

B
$$\left[ A \right] <\left[ B \right] $$

C
$$\left[ B \right] =\left[ C \right] $$

D
$$\left[ A \right] >\left[ B \right] $$

Solution

For the reaction,
$$\underset{2\\2-2x}{2A(g)}+\underset{2\\2-x}{B(g)}\rightleftharpoons \underset{0\\3x}{3C(g)}+\underset{0\\x}D(g)$$

2 moles each of $$A$$ and $$B$$ were taken into a flask. The consumption of A is twice of that of B.

Hence, $$\left[ A \right]_{eqm} <\left[ B \right]_{eqm} $$

Also from the reaction stoichiometry,

$$-\dfrac {1}{2}\dfrac {d}{dt}[A] =-\dfrac {d}{dt}[B] $$
or
$$- \dfrac {d}{dt}[A] =-2\dfrac {d}{dt}[B] $$

The rate of consumption of A is twice the rate of consumption of B.

So the equilibrium concentration of A will be less than the equilibrium concentration of B.

Option B is correct.

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Equilibrium Test - 30

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Equilibrium Test - 30

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Question 1

Increased production of products

Increased production of reactants

Fluctuations in the amounts of reactants and products

No impact on the equilibrium

Cannot be determined

Solution

Question 2

nature of the solvent

nature of the electrolyte

dilution

molecular mass of the electrolyte

Solution

Question 3

the electron is initially shared between both atoms, thus the dissociation event into ions involves the transfer of an electron from one atom to the other

it does not involve any electron transfer

charged species formed

no charge species formed

Solution

Question 4

$$(i),(ii),(iii)$$

$$(ii),(iii),(iv)$$

$$(i),(iii),(iv)$$

$$(i),(ii),(iii),(iv)$$

Solution

Question 5

State of rest

Dynamic state

Stationary state

State of inertness

Solution

Question 6

25.22

48.15

53.5

90

Solution

Question 7

will increase the dissociation of $$P{ Cl }_{ 5 }$$ as well as $${ N }_{ 2 }{ O }_{ 4 }$$

will reduce the dissociation of $$P{ Cl }_{ 5 }$$ as well as $${ N }_{ 2 }{ O }_{ 4 }$$

will increase the dissociation of $$P{Cl}_{5}$$ and step up the formation of $${NO}_{2}$$

will not disturb the equilibrium of the reaction

Solution

Question 8

doubling the volume

increasing the temperature

addition of equimolar quantities of $$P{Cl}_{3}$$ and $$P{Cl}_{5}$$

addition of $${Cl}_{2}$$ at constant volume

Solution

Question 9

Favours backward

Favours forward reaction

Has no effect

Increases the reaction rate

Solution

Question 10

$$\left[ A \right] =\left[ B \right] $$

$$\left[ A \right] <\left[ B \right] $$

$$\left[ B \right] =\left[ C \right] $$

$$\left[ A \right] >\left[ B \right] $$

Solution

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