Answer:
0.39 mol
Explanation:
Considering the ideal gas equation as:
where,
P is the pressure
V is the volume
n is the number of moles
T is the temperature
R is Gas constant having value = 0.0821 L.atm/K.mol
At same volume, for two situations, the above equation can be written as:-
Given ,
n₁ = 1.50 mol
n₂ = ?
P₁ = 3.75 atm
P₂ = 0.998 atm
T₁ = 21.7 ºC
T₂ = 28.1 ºC
The conversion of T( °C) to T(K) is shown below:
T(K) = T( °C) + 273.15
So,
T₁ = (21.7 + 273.15) K = 294.85 K
T₂ = (28.1 + 273.15) K = 301.25 K
Using above equation as:

Solving for n₂ , we get:
n₂ = 0.39 mol
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Answer:
As solute concentration increases, vapor pressure decreases.
Step-by-step explanation:
As solute concentration increases, the number of solute particles at the surface of the solution increases, so the number of <em>solvent </em>particles at the surface <em>decreases</em>.
Since there are fewer solvent particles available to evaporate from the surface, the vapour pressure decreases.
C. and D. are <em>wrong</em>. The vapour pressure depends <em>only</em> on the number of particles. It does not depend on the nature of the particles.