Thermodynamics Test

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Thermodynamics Test - 64

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Weekly Quiz Competition

Question 1
1 / -0

The value of $$\Delta G$$ for the process $${ H }_{ 2 }O\left( s \right) \rightarrow { H }_{ 2 }O\left( l \right)$$ at 1 atm and 260 K is:

A
<0

B
=0

C
>0

D
unpredictable

Solution

At $$T<273K$$ ice remains as ice and water converts into ice. So, ice to water conversion is not a spontaneous process.
$$\Rightarrow$$ $$\Delta G>0$$ for $${ H }_{ 2 }O\left( s \right) \longrightarrow { H }_{ 2 }O\left( l \right) $$ at $$260K$$.
Ans :- C
Question 2
1 / -0

Statement I: In adsorption process, the value of $$\Delta H$$ is always negative.
Statement II: During adsorption surface area of adsorbent decreases.
Which of the above statement is/are true? Choose the correct option.

A
Only I

B
Only II

C
I and II

D
None of these

Solution
Question 3
1 / -0

For the reversible isothermal expansion of one mole of an ideal gas at $$300$$ $$K$$, from a volume of $$10 L$$ to $$20 L$$, $$\Delta H$$ is :

A
$$1.73 \ kJ$$

B
$$-1.73 \ kJ$$

C
$$3.46 \ kJ$$

D
0

Solution
Question 4
1 / -0

For the process $${ H }_{ 2 }O(1,1bar,373.15k)\rightarrow { H }_{ 2 }O(g,1bar,373.15k)$$, the correct set of thermodynamic parameters is:

A
$$\Delta G\ =\ 0,\ \Delta S\ =\ +\ ve$$

B
$$\Delta G\ =\ 0,\ \Delta S\ =\ -ve$$

C
$$\Delta G\ =\ +ve,\ \Delta S\ =\ 0$$

D
$$\Delta G\ =\ -ve,\ \Delta S\ =\ +ve$$
Question 5
1 / -0

For reversible isothermal expansion of one mole of an ideal gas at $$300 K$$, from a volume of $$10 L$$ to $$20 L$$, $$\Delta H$$ is :

A
$$1.73 kJ$$

B
$$-1.73 kJ$$

C
$$3.46 kJ$$

D
zero

Solution
Question 6
1 / -0

For the hypothetical reaction: $${ A }_{ 2 }\left( g \right) +{ B }_{ 2 }\left( g \right) \rightleftharpoons 2AB\left( g \right)$$

$${ \Delta }_{ r }G$$ and $${ \Delta }_{ r }S$$ are $$20\ { kJ }/{ mole }$$ and $$-20\ { Jk }^{ -1 }{ mole }^{ -1 }$$ respectively at 200 K. If $${ \Delta }_{ r }{ C }_{ p }$$ is $$20\ { Jk }^{ -1 }{ mole }^{ -1 }$$ then $${ \Delta }_{ r }H$$ at 400 K is:

A
$$20\ { kJ }/{ mole }$$

B
$$7.98\ { kJ }/{ mole }$$

C
$$28\ { kJ }/{ mole }$$

D
None of these

Solution
Question 7
1 / -0

Two reactions are given below:$${ CO }_{ \left( g \right) }+\dfrac { 1 }{ 2 } { O }_{ 2\left( g \right) }\rightarrow { CO }_{ 2\left( g \right) }$$$${ { Ag }_{ 2 }O }_{ \left( s \right) }\rightarrow { 2Ag }_{ \left( s \right) }+\dfrac { 1 }{ 2 } O_{ 2\left( g \right) }$$Which of the following statements is true?

A
For (i) $$ \Delta H<\Delta E$$ and for (ii) $$\Delta H>\Delta E$$

B
For (i) $$\Delta H>\Delta E$$ and for (ii) $$ \Delta H<\Delta E$$

C
For both (i) and (ii) $$ \Delta H>\Delta E$$

D
For both (i) and (ii) $$ \Delta H<\Delta E$$

Solution
Question 8
1 / -0

Mayuri was performing thermometric titration and she took 100 ml of $$1 M$$ sulphuric acid and started adding $$1 M$$ calcium hydroxide. When she plotted a graph of temperature vs volume of the titrant added, she found that the temperature was initially increasing and then it started decreasing. The maximum of the graph is obtained at 100 ml of calcium hydroxide. What will be the enthalpy change of this reaction?
[Given: $$\Delta H\ = -13.7 kcal/eq$$]

A
-13.7 kcal

B
-27.4 kcal

C
-1.37 kcal

D
-2.74 kcal
Question 9
1 / -0

$$(CH_3)_2CH + Cl_2 \longrightarrow (CH_3)_2CHCl + Cl$$
$$CH_3CH_2CH_2 - H$$ $$98$$
$$(CH_3)_2CH - H$$ $$95$$
$$Cl - Cl$$ $$58$$
$$H - Cl$$ $$103$$
$$CH_3CH_2CH_2 - Cl$$ $$81$$
$$(CH_3)_2CH -Cl$$ $$80$$
Given the bond dissociation energies below (in $$kcal/mole$$), estimate the $${ \Delta H }^{ o }$$ for the propagation step:

A
$$-30\ kcal/mole$$

B
$$+22\ kcal/mole$$

C
$$-40\ kcal/mole$$

D
$$+45\ kcal/mole$$
Question 10
1 / -0

$$aA + bB \rightleftharpoons cC + dD$$
in the above reaction, low pressure and high-temperature conditions shift the equilibrium in the backward direction, then which of the following is true?

A
$$(a + b) > (c + d), \triangle H > 0$$

B
$$(a + b) < (c + d), \triangle H > 0$$

C
$$(a + b) < (c + d), \triangle H < 0$$

D
$$(a + b) > (c + d), \triangle H < 0$$

Solution

Solution:- (D) $$\left( a + b \right) > \left( c + d \right), \quad \Delta{H} < 0$$
$$aA + bB \rightleftharpoons cC + dD$$
When pressure is decreased, the equilibrium will shift in a direction in which there is an increase in the number of moles. Due to this, the pressure will increase and invalidate the decrease in pressure. When the temperature of an exothermic reaction is increased, the reaction will proceed in the backward direction so as to absorb heat and invalidate the effect of increasing temperature. This will decrease the value of the equilibrium constant $${K}_{C}$$, i.e., the equilibrium will shift to left. The equilibrium shifts in the backward direction by low pressure and high temperature. This indicates that the total no. of moles of reactant is greater than the total no. of moles of product, i.e.,
$$\left( a + b \right) > \left( c + d \right)$$.
This indicates that the reaction is exothermic, i.e.,
$$\Delta{H} < 0$$