The vapor pressure of pure water at 30C is 31.8Torr. What is the vapor pressure of a solution of NaCl dissolved in water when the mole fraction of NaCl is 0.111?
I am wondering if this would be correct.
0.11*31.8= 3.5 Torr
Is there another way to solve this and get the same answer?
To find the vapor pressure of a solution of NaCl dissolved in water, you can use Raoult's Law.
Raoult's Law states that the vapor pressure of a solution is equal to the mole fraction of the solvent multiplied by the vapor pressure of the pure solvent. The mole fraction of the solvent (water) can be calculated by taking the ratio of the moles of water to the total moles of solute and solvent.
In this case, the mole fraction of NaCl (solute) is given as 0.111. Since the sum of the mole fractions of all components in a solution must be equal to 1, the mole fraction of water (solvent) would be 1 - 0.111 = 0.889.
Now, you can use Raoult's Law to find the vapor pressure of the solution:
Vapor Pressure of the solution = Mole fraction of water * Vapor pressure of water
Vapor Pressure of the solution = 0.889 * 31.8 Torr
Calculating this value,
Vapor Pressure of the solution ≈ 28.2562 Torr
Therefore, the correct vapor pressure of the solution of NaCl dissolved in water, when the mole fraction of NaCl is 0.111, is approximately 28.2562 Torr.
So, your initial answer of 3.5 Torr is not correct. The correct way to solve this using Raoult's Law yields an answer of approximately 28.2562 Torr.