Vant Hoff's Equation and Effect of Temperature on Equilibrium Constant

Q.

Question 09
Which of the following aqueous solutions should have the highest boiling point?
(a) 1.0 M NaOH (b) $1.0MN{a}_{2}S{O}_4$
(C)$1.0MN{H}_{4}N{O}_3$ (d) $1.0MKN{O}_3$

Q. The boiling point of an aqueous solution of a non-volatile solute is $100.15{}^{\circ }C$. What is the freezing point of an aqueous solution obtained by diluting the above solution with an equal volume of water?
The value of $K_b$ and $K_f$ for water are $0.512{}^{\circ }\text{C kg/mol}$ and $1.86{}^{\circ }\text{C kg/mol}$ respectively.

1. $-0.545{}^{\circ }C$
2. $-0.520{}^{\circ }C$
3. $-0.273{}^{\circ }C$
4. $-1.86{}^{\circ }C$

Q.

What is K in chemistry ?

Q.

How does Temperature affect Equilibrium Exothermic?

Q.

Dihydrogen gas is obtained from natural gas by partial oxidation with steam as per following endothermic reaction:
(i) $C{H}_4\left(g\right)+H_{2}O\left(g\right)\leftrightarrow CO\left(g\right)+3H_2\left(g\right)$
Write as expression for $K_p$ for the above reaction

(ii) $C{H}_4\left(g\right)+H_{2}O\left(g\right)\leftrightarrow CO\left(g\right)+3H_2\left(g\right)$
How will the values of $K_p$ and compositioon of equilibrium mixture be affected by
(i) Increasing the pressure
(ii) Increasing the temperature
(iii) Using a catalyst?

Q. The following data were obtained at a certain temperature for the decomposition of ammonia in contact with tungsten:

$\begin{array}{cccc}\text{Relative}{t}_{1/2}& 3.64& 1.82& 0.91\\ \text{p(mm)}& 50& 100& 200\end{array}$
($t_{1/2}$ is the half life and $\text{p}$ is the partial pressure of ammonia at different intervals.)
Find the order of the reaction.

1. $1$
2. $2$
3. $0$
4. $3$

Q. The variation of equilibrium constant ($K$) of a certain reaction with temperature ($T$) is $\ln K=3.0+\frac{2.0\times {10}^4}{T}$ given $R=8.3J{K}^{-1}mo{l}^{-1}$, the values of $\Delta H^o$ and $\Delta S^o$ are:

1. $\Delta H^o=-166kJ/mol$
2. $\Delta H^o=+166kJ/mol$
3. $\Delta S^o=+24.9kJ/mol$
4. $\Delta S^o=-24.9kJ/mol$

Q.

What is the thermochemical equation?

Q. Which of the following is produced in the third step in contact process?

1. Sulphur dioxide
2. Sulphur trioxide
3. Pyrosulphuric acid
4. Sulphurous acid

Q.

For a reaction, $4\mathrm{M}\left(\mathrm{s}\right)+{\mathrm{nO}}_2\left(\mathrm{g}\right)\to 2{\mathrm{M}}_2{\mathrm{O}}_{\mathrm{n}}\left(\mathrm{s}\right)$ the free energy change is plotted as a function of temperature. The temperature below which the oxide is stable could be inferred from the plot as the point at which

1. The free energy change shows a change from negative to positive value.

2. The slope changes from positive to zero.

3. The slope changes from positive to negative.

4. The slope changes from negative to positive.

Q.

For a given equilibrium reaction, an increase in temperature will

1. Increase both rates equally.

2. Increase the rate of the exothermic reaction more than that of the endothermic reaction.

3. Increase the rate of the endothermic reaction more than that of the exothermic reaction.

4. Decreases both rates equally.

Q.

How do you know if a reaction is at equilibrium?

Q. An exothermic reaction is represented by the graph :

1. 
2. 
3. 
4. 

Q. Which of the following reaction will proceed in forward direction on decreasing the temperature?

1. $H_2\left(g\right)+I_2\left(g\right)\rightleftharpoons 2HI\left(g\right){\Delta }_{r}H=+3000\text{cal}$
2. $2N{H}_3\left(g\right)\rightleftharpoons N_2\left(g\right)+3H_2\left(g\right){\Delta }_{r}H=+22400\text{cal}$
3. $N_2\left(g\right)+O_2\left(g\right)\rightleftharpoons 2NO\left(g\right){\Delta }_{r}H=-43200\text{cal}$
4. $C{O}_2\left(g\right)\rightleftharpoons C\left(s\right)+O_2\left(g\right){\Delta }_{r}H=+94300\text{cal}$

Q. According to Van't Hoff equation, which of the following statement is correct regarding the plot of $\ln K_{eq}\text{v/s}\frac{1}{T}$ ?

1. For an endothermic reaction, the slope is $\frac{\Delta S^{\circ }}{RT}$
2. For an endothermic reaction, the slope is $\frac{-\Delta H^{\circ }}{R}$
3. For an exothermic reaction, the slope is $\frac{\Delta S^{\circ }}{R}$
4. For an exothermic reaction, the slope is $\frac{-\Delta H^{\circ }}{RT}$

Q.

How can you convert the following: Sulphuric acid to sulphur dioxide?

Q. A schematic plot of ln $k_{eq}$ vs inverse of temperature for a reaction is shown below:

The reaction must be

1. Exothermic
2. Endothermic
3. One with negligible enthalpy change
4. Highly spontaneous at ordinary temperature

Q. Change in volume of the system does not alter which of the following equilibria?

1. $N_2\left(g\right)+O_2\left(g\right)\rightleftharpoons 2NO\left(g\right)$
2. $PC{l}_5\left(g\right)\rightleftharpoons PC{l}_3\left(g\right)+C{l}_2\left(g\right)$
3. $N_2\left(g\right)+3H_2\left(g\right)\rightleftharpoons 2N{H}_3\left(g\right)$
4. $S{O}_{2}C{l}_2\left(g\right)\rightleftharpoons S{O}_2\left(g\right)+C{l}_2\left(g\right)$

Q.

For the reaction ${\mathrm{Zr}}_3{\left({\mathrm{PO}}_4\right)}_4$ the solubility product is ${\mathrm{K}}_{\mathrm{sp}}$ and solubility is $\mathrm{S}$. Find the correct relation.

1. $S={\left(\frac{K_{sp}}{6912}\right)}^{1/2}$

2. $S={\left(\frac{K_{sp}}{216}\right)}^{1/7}$

3. $S={\left(\frac{K_{sp}}{216}\right)}^{1/8}$

4. $S={\left(\frac{K_{sp}}{912}\right)}^{1/3}$

Q. According to Van't Hoff equation, which of the following statement is correct regarding the plot of $\ln K_{eq}\text{v/s}\frac{1}{T}$ ?

1. For an endothermic reaction, the slope is $\frac{-\Delta H^{\circ }}{R}$
2. For an exothermic reaction, the slope is $\frac{\Delta S^{\circ }}{R}$
3. For an exothermic reaction, the slope is $\frac{-\Delta H^{\circ }}{RT}$
4. For an endothermic reaction, the slope is $\frac{\Delta S^{\circ }}{RT}$

Q. Consider a reaction:
$N_2\left(g\right)+3H_2\left(g\right)\rightleftharpoons 2N{H}_3\left(g\right)$
Given that ,
$K_{eq}=7\times {10}^5$
$\Delta S_{N{H}_3}^{\circ }=-23.66calmo{l}^{-1}{K}^{-1}$
Both the values are at 300K
Find the value of $\Delta H_{N{H}_3}^{\circ }$ at 300 K
Take $ln\left(7\right)=1.95$

1. $-35.46kcalmo{l}^{-1}$
2. $-85.2kcalmo{l}^{-1}$
3. $-15.16kcalmo{l}^{-1}$
4. $-65.4kcalmo{l}^{-1}$

Q. Which of the following happens when a catalyst is added to a reaction at equilibrium?

1. The point of equilibrium is shifted to the right
2. The point of equilibrium is shifted to the left
3. The forward and reverse reactions rates are increased uneqully
4. The forward and reverse reactions rates are increased equally
5. None of these

Q. The elevation of boiling point of $0.10m$ aqueous $CrC{1}_3.xN{H}_3$ solution is two times that of $0.05m$ aqueous $CaC{l}_2,$ solution. The value of $x$ is _______ [Assume $100\%$ ionisation of the complex and $CaC{l}_2$, coordination number of $Cris6$, and that all $N{H}_3$ molecules are present inside the coordination sphere]

Q. For the reaction $PC{l}_5\left(g\right)\leftrightharpoons PC{l}_3\left(g\right)+C{l}_2\left(g\right),$ the forward reaction at constant temperature is favored by –

1. Introducing an inert gas at constant volume
2. Introducing chlorine gas at constant volume
3. Introducing an inert gas at constant pressure
4. Decreasing the volume of container

Q. Given reaction is
$3X\left(g\right)+Y\left(g\right)\rightleftharpoons 3Z\left(g\right)$
$\Delta H=+35kJ$
Which conditions will give the highest yield of $Z$ at equilibrium?

1. High temperature and high pressure.
2. High temperature and low pressure.
3. Low temperature and high pressure.
4. Low temperature and low pressure.

Q. For the reaction H${}_2$ (g) + I${}_2$(g)$\rightleftharpoons$2HI(g), K${}^o$${}_c$= 66.9 at 350${}^{\circ }$C and K${}^o$${}_c$= 50.0 at 448 ${}^{\circ }$C. The reaction has

1. H = +ve.

2. H = -ve.

3. H whose sign cannot be predicted

4. H = Zero

Q. In the following reversible reaction $2S{O}_2\left(g\right)+O_2\left(g\right)\rightleftharpoons 2S{O}_3\left(g\right),\Delta H=+Qcal$,
where Q is negative. Most suitable condition for a low production of $S{O}_3$ is:

1. Low temperature and low pressure
2. High temperature and low pressure
3. Low temperature and high pressure
4. High temperature and high pressure

Q.

In the reaction $N_2\left(g\right)+3H_2\left(g\right)\rightleftharpoons 2N{H}_3\left(g\right)$, the value of the equilibrium

constant depends on

1. The temperature

2. Volume of the reaction vessel

3. Total pressure of the system

4. The initial concentration of nitrogen and hydrogen

Q.

For an equilibrium reaction A (g) + B (g)$\rightleftharpoons$ C (g) + D (g), $\Delta H$ = +ve. An increase in temperature would cause

1. An increase in the value of

2. No change in the value of

3. A change in which cannot be qualitatively predicted

4. A decrease in the value of

Q.

For an equilibrium reaction A (g) + B (g) $\rightleftharpoons$ C (g) + D (g), $\Delta H$ = -ve. An increase in temperature would cause

1. No change in the value of

2. A decrease in the value of

3. A change in which cannot be qualitatively predicted

4. An increase in the value of