Question

What is the molarity of a solution made by dissolving 26.42 g of (NH_4)_2 SO_4 in enough water to make 50 ml of solution?

Options:
Option 1: 4 M
Option 2: 40 M
Option 3: 0.4 M

Answer 1

The molarity of the solution is calculated by dividing the number of moles of (NH4)2SO4 (which is 0.2 mol) by the volume in liters (0.05 L), yielding a molarity of 4 M.

Step-by-step explanation:

The molarity of a solution is calculated by dividing the number of moles of the solute by the volume of the solution in liters. In this case, we first need to calculate the number of moles of (NH4)2SO4 by using its molar mass.

Molar mass of (NH4)2SO4 = (2 × 14.007) + (8 × 1.008) + 32.065 + (4 × 15.999) = 132.14 g/mol

Number of moles = 26.42 g ÷ 132.14 g/mol = 0.2 mol

Now, we convert the volume of the solution from milliliters to liters: 50 mL = 0.05 L.

Thus, the molarity (M) of the solution is:

0.2 mol ÷ 0.05 L = 4 M