Q4) Suppose you prepare 950 mL of a solution by dissolving 100 grams of NaCl in 900 mL of water. Assuming the density of pure water to be 1 g/mL, answer the following questions with regards to this solution:

a) What is the mass percent of water in this solution?
b) What is molarity of NaCl solution?
c) What is the mole fraction of NaCl in the solution?

a. mass % H2O = (grams H2O/grams soln)*100 = (100g H2O/1000g)*100 = ?

b. M = moles NaCl/L soln = moles NaCl/0.950 = ?
moles NaCl = grams NaCl/molar mass

c. mols NaCl you have.
mols H2O = grams H2O/molar mass
total moles = ?

XNaCl = moles NaCl/total moles.

a) To find the mass percent of water in the solution, we need to know the mass of water in the solution and the total mass of the solution.

First, let's calculate the mass of water in the solution. Since the density of pure water is 1 g/mL, we can assume that 900 mL of water has a mass of 900 grams.

Next, let's calculate the total mass of the solution. The mass of NaCl used is given as 100 grams. Therefore, the total mass of the solution is 900 grams (mass of water) + 100 grams (mass of NaCl) = 1000 grams.

Now, we can calculate the mass percent of water using the formula:

Mass percent of water = (mass of water / total mass of solution) * 100

Substituting the values, we get:

Mass percent of water = (900 grams / 1000 grams) * 100 = 90%

So, the mass percent of water in this solution is 90%.

b) To find the molarity of the NaCl solution, we need to know the number of moles of NaCl and the volume of the solution.

The number of moles of NaCl can be calculated using the formula:

Moles = Mass / molar mass

The molar mass of NaCl is 58.44 g/mol (23 + 35.45).

Substituting the values, we get:

Moles of NaCl = 100 grams / 58.44 g/mol = 1.71 moles

The volume of the solution is given as 950 mL, which is equivalent to 0.95 L.

Now, we can calculate the molarity of the NaCl solution using the formula:

Molarity (M) = Moles of solute / Volume of solution (in liters)

Substituting the values, we get:

Molarity of NaCl solution = 1.71 moles / 0.95 L = 1.80 M

So, the molarity of the NaCl solution is 1.80 M.

c) To find the mole fraction of NaCl in the solution, we need to know the moles of NaCl and the moles of all components in the solution.

The moles of all components in the solution can be calculated as the sum of the moles of NaCl and the moles of water.

The moles of water can be calculated using the formula:

Moles = Mass / molar mass

The molar mass of water is 18.015 g/mol.

Substituting the values, we get:

Moles of water = 900 grams / 18.015 g/mol = 49.94 moles

The total moles of all components in the solution is 1.71 moles (moles of NaCl) + 49.94 moles (moles of water) = 51.65 moles.

Now, we can calculate the mole fraction of NaCl in the solution using the formula:

Mole fraction of NaCl = Moles of NaCl / Moles of all components

Substituting the values, we get:

Mole fraction of NaCl = 1.71 moles / 51.65 moles = 0.033

So, the mole fraction of NaCl in the solution is 0.033.