Question

Consider the reaction equilibrium
$\mathop {{\text{ice}}\,}\limits_{{\text{greater}}\,{\text{volume}}} \, \rightleftarrows \mathop {{\text{water}}}\limits_{{\text{lesser volume}}} \, - \,{\text{X}}\,{\text{kcal}}$
The favourable condition for forward reaction are:
A. Low temperature, high pressure and excess of ice.
B. Low temperature low pressure and excess of ice.
C. High temperature, low pressure and excess of ice.
D. High temperature, high pressure and excess of ice.

Answer 1

We can use the Le-chatlier principle. The increased concentration of reactants or products favors the reaction in that direction where the increased concentration can be utilized. The ice requires heat to melt. Pressure and volume are inversely proportional according to the ideal gas equation.

Complete answer:
According to the Le-chatlier principle if a reaction equilibrium is disturbed by changing the variable such as temperature, pressure number of mole, the reaction goes in that direction where the effect of change can be cancelled out.
1. Effect of concentration of reactant: On increasing the concentration of reactant the reaction goes in a forward direction to utilize the increased amount of reactant.
2. Effect of volume: Pressure and volume are inversely proportional so, as the volume is decreasing the pressure of the reaction is increasing so, high pressure will favour the reaction in forward direction.
3. Effect of temperature: The ice to water conversion is an endothermic reaction, on increasing the temperature the content of heat will increase which will be utilized by the ice to melt, so, the reaction will go in a forward direction so, high temperature will favour the reaction in a forward direction.
So, low temperature, high pressure, and excess of ice will favour the reaction in the forward direction.

Therefore, option (D) High-temperature high pressure and excess of ice, is correct.

Note: Increased concentration of product always favour the reaction in a backward direction. The high temperature favors the endothermic reaction and low-temperature favour the exothermic reaction. On increasing pressure the reaction goes in that direction lesser number moles of gaseous species a represent.