An ideal solution was found to have a vapour pressure of 80 torr when ...
Mole fraction of solute = 0.2
mole fraction of solvent = 1 - 0.2 = 0.8
Psolution = Xsolvent*Pdegsolvent
80 = 0.8*Pdeg solvent
Pdeg solvent = 100torr
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An ideal solution was found to have a vapour pressure of 80 torr when ...
To find the vapour pressure of the pure solvent at the same temperature, we can use Raoult's Law. According to Raoult's Law, the vapour pressure of a solution is directly proportional to the mole fraction of the solvent.
Vapour pressure of the solution = mole fraction of solvent * vapour pressure of pure solvent
Given that the mole fraction of the solute is 0.2 and the vapour pressure of the solution is 80 torr, we can rearrange the equation to solve for the vapour pressure of the pure solvent:
Vapour pressure of pure solvent = Vapour pressure of solution / mole fraction of solvent
Substituting the given values into the equation:
Vapour pressure of pure solvent = 80 torr / 0.2
Vapour pressure of pure solvent = 400 torr
Therefore, the vapour pressure of the pure solvent at the same temperature is 400 torr.
Explanation:
- Raoult's Law states that the vapour pressure of a solution is directly proportional to the mole fraction of the solvent.
- The mole fraction of a component in a solution is the ratio of the number of moles of that component to the total number of moles in the solution.
- In this case, the non-volatile solute has a mole fraction of 0.2, which means it makes up 20% of the total number of moles in the solution.
- The vapour pressure of the solution is given as 80 torr.
- To find the vapour pressure of the pure solvent, we use Raoult's Law and divide the vapour pressure of the solution by the mole fraction of the solvent.
- Substituting the given values into the equation, we find that the vapour pressure of the pure solvent is 400 torr.
- Therefore, the correct answer is option C.
An ideal solution was found to have a vapour pressure of 80 torr when ...