The vapor pressure of solution, at constant temperature, is linearly dependent on mole fraction Select one: O True O False
The answer is true.
According to Raoult's Law, for a solution containing volatile substance, the partial vapor pressure of that substance is directly proportional to the mole fraction of the substance dissolved in the solution.
Thus, let us assume a binary solution having A and B as components, then as per Raoult's Law:
Pa is directly proportional to xa equation (1)
where Pa = Partial vapor pressure of A
xa = mole fraction of A in solution
Therefore, to obtain a relation from equation (1), we put a constant P0a which is pure pressure of A when it is present alone in a container at a same temperature.
hence, the equation now becomes,
Pa = P0a xa equation (2)
Similarly, for another component B, the partial vapor pressure of B is directly proportional to its mole fraction in the solution.
Pb is directly proportional to xa equation (3)
where Pb = partial vapor pressure of B
xb= mole fraction of B in solution
To obtain an equation, we insert a constant P0b where it is pure pressure of B when it is present alone in the container at the same temperature.
Hence, we get
Pb = P0b xb equation (4)
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