Question

5. Lab instructions tell you to dissolve 50 grams of AgNO3 in 400 mL of water. Later in the lab, the

procedure tells you to pour 20 mL of the AgNO3 solution into 20 mL of water. What is the molarity
of the diluted solution?

Answer 1

The molarity of the original solution can be calculated as follows:

Molarity = moles of solute / volume of solution (in liters)

We first need to calculate the moles of AgNO3 in 50 grams.

Moles of AgNO3 = mass / molar mass = 50 g / 169.87 g/mol = 0.294 moles

Next, we need to calculate the volume of the original solution in liters.

Volume of solution = 400 mL = 0.4 L

So the molarity of the original solution is:

Molarity = 0.294 moles / 0.4 L = 0.735 M

When 20 mL of the original solution is diluted with 20 mL of water, the volume of the resulting solution is 40 mL = 0.04 L.

To calculate the molarity of the diluted solution, we need to calculate the moles of AgNO3 in 20 mL of the original solution, and then divide by the volume of the diluted solution in liters.

Moles of AgNO3 in 20 mL = 0.735 M x 0.02 L = 0.0147 moles

Molarity of the diluted solution = 0.0147 moles / 0.04 L = 0.368 M

Therefore, the molarity of the diluted solution is 0.368 M.