Question

10.0 g of an alkali metal chloride salt is dissolved in 90.0 g h2o. this solution has a vapor pressure that is 3.2% lower than that of pure water at the same temperature. what is the salt?

Answer 1

To determine the salt, we need to calculate the vapor pressure lowering using Raoult's Law and solve the given calculations.

Step-by-step explanation:

The decrease in vapor pressure of a solution compared to that of the pure solvent is known as vapor pressure lowering. In this case, the solution of an alkali metal chloride salt in water has a vapor pressure that is 3.2% lower than that of pure water at the same temperature. To determine the salt, we need to calculate the vapor pressure lowering using Raoult's Law.

1. First, we need to convert the mass of the salt and water into moles.
2. We can then calculate the mole fraction of the salt in the solution using the moles of salt and water.
3. Next, we can use Raoult's Law, which states that the vapor pressure of a component in a solution is equal to the vapor pressure of the pure component multiplied by its mole fraction in the solution.
4. We can substitute the given values into Raoult's Law to find the vapor pressure of the solution.
5. Finally, we can calculate the vapor pressure lowering by subtracting the vapor pressure of the solution from the vapor pressure of pure water.

By solving these calculations, we can determine the salt present in the solution.

Answer 2

The decrease in vapor pressure can be attributed to the dissolved salt particles in the water, leading to boiling point elevation. The exact formula of the salt cannot be determined without the boiling point elevation constant.

Step-by-step explanation:

In this question, we are given that 10.0 g of an alkali metal chloride salt is dissolved in 90.0 g of water and that the solution has a vapor pressure 3.2% lower than that of pure water at the same temperature.

The decrease in vapor pressure can be attributed to the presence of the dissolved salt particles in the water. This phenomenon is known as boiling point elevation.

By comparing the decrease in vapor pressure to the boiling point elevation constant for water, the formula of the salt can be determined. However, without the boiling point elevation constant, it is not possible to calculate the exact formula of the salt.