Answer
Verified
64.8k+ views
Hint: The ionic product of water is the product of concentrations of ${{\text{H}}^{\text{ + }}}$ and ${\text{O}}{{\text{H}}^ - }$ ions in water at a particular temperature. It is denoted by ${{\text{K}}_{\text{w}}}$
Step-by-Step Explanation: Water is a weak electrolyte and ionizes only to a small extent. ‘The ionic product of the water is the product of concentrations of ions in which it is dissociated at a particular temperature’. The water is dissociated in the following manner-
$ \Rightarrow {{\text{H}}_2}{\text{O}} \rightleftharpoons {{\text{H}}^{\text{ + }}} + {\text{O}}{{\text{H}}^ - }$
Then ${{\text{K}}_{\text{w}}}$=$\dfrac{{\left[ {{{\text{H}}^{\text{ + }}}} \right]\left[ {{\text{O}}{{\text{H}}^ - }} \right]}}{{\left[ {{{\text{H}}_2}{\text{O}}} \right]}}$
$ \Rightarrow {{\text{K}}_{\text{w}}}\left[ {{{\text{H}}_2}{\text{O}}} \right] = \left[ {{{\text{H}}^{\text{ + }}}} \right]\left[ {{\text{O}}{{\text{H}}^ - }} \right]$
Because $\left[ {{{\text{H}}_2}{\text{O}}} \right] = 1$ then,
$ \Rightarrow {{\text{K}}_{\text{w}}} = \left[ {{{\text{H}}^{\text{ + }}}} \right]\left[ {{\text{O}}{{\text{H}}^ - }} \right]$
Ionic products are temperature dependent because the Ionic product is directly proportional to the temperature.
By Le-Chatelier’s principle, as the temperature increases, the position of equilibrium shifts to the right of the equation to minimize the effect of increased temperature.
This means with the increase in temperature the concentration of$\left[ {{{\text{H}}^{\text{ + }}}} \right]$ and$\left[ {{\text{O}}{{\text{H}}^ - }} \right]$ ions will increase which will result in increased value of${{\text{K}}_{\text{w}}}$ as forward reaction is favoured.
This means that the ionic product depends only on temperature and is unaffected by any other changes.
Hence correct answer is ‘D’.
Note: Since concentration of hydrogen ion increases when temperature is increased and we know that pH is inversely proportional to concentration of hydrogen ion then the pH of water will decrease with increase in temperature. Also,
When,$\left[ {{{\text{H}}^{\text{ + }}}} \right] = \left[ {{\text{O}}{{\text{H}}^ - }} \right]$ then the solution is neutral [pure water is neutral].
When $\left[ {{{\text{H}}^{\text{ + }}}} \right] > \left[ {{\text{O}}{{\text{H}}^ - }} \right]$ then the solution becomes acidic.
When $\left[ {{{\text{H}}^{\text{ + }}}} \right] < \left[ {{\text{O}}{{\text{H}}^ - }} \right]$ then the solution becomes basic.
Step-by-Step Explanation: Water is a weak electrolyte and ionizes only to a small extent. ‘The ionic product of the water is the product of concentrations of ions in which it is dissociated at a particular temperature’. The water is dissociated in the following manner-
$ \Rightarrow {{\text{H}}_2}{\text{O}} \rightleftharpoons {{\text{H}}^{\text{ + }}} + {\text{O}}{{\text{H}}^ - }$
Then ${{\text{K}}_{\text{w}}}$=$\dfrac{{\left[ {{{\text{H}}^{\text{ + }}}} \right]\left[ {{\text{O}}{{\text{H}}^ - }} \right]}}{{\left[ {{{\text{H}}_2}{\text{O}}} \right]}}$
$ \Rightarrow {{\text{K}}_{\text{w}}}\left[ {{{\text{H}}_2}{\text{O}}} \right] = \left[ {{{\text{H}}^{\text{ + }}}} \right]\left[ {{\text{O}}{{\text{H}}^ - }} \right]$
Because $\left[ {{{\text{H}}_2}{\text{O}}} \right] = 1$ then,
$ \Rightarrow {{\text{K}}_{\text{w}}} = \left[ {{{\text{H}}^{\text{ + }}}} \right]\left[ {{\text{O}}{{\text{H}}^ - }} \right]$
Ionic products are temperature dependent because the Ionic product is directly proportional to the temperature.
By Le-Chatelier’s principle, as the temperature increases, the position of equilibrium shifts to the right of the equation to minimize the effect of increased temperature.
This means with the increase in temperature the concentration of$\left[ {{{\text{H}}^{\text{ + }}}} \right]$ and$\left[ {{\text{O}}{{\text{H}}^ - }} \right]$ ions will increase which will result in increased value of${{\text{K}}_{\text{w}}}$ as forward reaction is favoured.
This means that the ionic product depends only on temperature and is unaffected by any other changes.
Hence correct answer is ‘D’.
Note: Since concentration of hydrogen ion increases when temperature is increased and we know that pH is inversely proportional to concentration of hydrogen ion then the pH of water will decrease with increase in temperature. Also,
When,$\left[ {{{\text{H}}^{\text{ + }}}} \right] = \left[ {{\text{O}}{{\text{H}}^ - }} \right]$ then the solution is neutral [pure water is neutral].
When $\left[ {{{\text{H}}^{\text{ + }}}} \right] > \left[ {{\text{O}}{{\text{H}}^ - }} \right]$ then the solution becomes acidic.
When $\left[ {{{\text{H}}^{\text{ + }}}} \right] < \left[ {{\text{O}}{{\text{H}}^ - }} \right]$ then the solution becomes basic.
Recently Updated Pages
Write a composition in approximately 450 500 words class 10 english JEE_Main
Arrange the sentences P Q R between S1 and S5 such class 10 english JEE_Main
What is the common property of the oxides CONO and class 10 chemistry JEE_Main
What happens when dilute hydrochloric acid is added class 10 chemistry JEE_Main
If four points A63B 35C4 2 and Dx3x are given in such class 10 maths JEE_Main
The area of square inscribed in a circle of diameter class 10 maths JEE_Main
Other Pages
A boat takes 2 hours to go 8 km and come back to a class 11 physics JEE_Main
In the ground state an element has 13 electrons in class 11 chemistry JEE_Main
Differentiate between homogeneous and heterogeneous class 12 chemistry JEE_Main
Electric field due to uniformly charged sphere class 12 physics JEE_Main
According to classical free electron theory A There class 11 physics JEE_Main
Excluding stoppages the speed of a bus is 54 kmph and class 11 maths JEE_Main