AP EAMCET202017 Sep 2020Evening ShiftChemistrySolutionsActual
Which of the following change decrease the vapour pressure of water kept in a sealed vessel?
Options
- ADecreasing the quantity of water
- BAdding salt to water
- CDecreasing the volume of the vessel to one-half
- DKeeping the temperature of water constant
Correct answer
B. Adding salt to water
Step-by-step solution
When salt (non-volatile solute) is added to water kept in a sealed vessel, boiling point of the solution will be elevated or increased. So, vapour pressure of water (solution) will be decreased. Lowering of vapour pressure ( ( p=p^ -p ) ) is also proportional to mole fraction of the solute ( ( _B ) ) present in the solution. ( p _B [p^ = . ) vapour pressure of pure water (p= ) vapour pressure of solution]