Question

A solution is made by dissolving 26.42g of (NH4)2so4 in enough h2o to make 50.00ml of solution

Answer 1

Molarity = moles of solute/liters of solution

We first need to convert grams of ammonium sulfate to moles.
To convert from grams to moles, we need to divide by it's molecular mass.

26.42 g (NH₄)₂SO₄ * (1 mole (NH₄)₂SO₄ / 132.14 g (NH₄)₂SO₄) = 0.1999 mole (NH₄)₂SO₄

0.1999 mol/0.05000L = 3.998 M

Since there 4 significant digits in both the volume and mass, we are limited to 4 significant digits.

Your final answer is 3.998 M (NH₄)₂SO₄.

Answer 2

Moles of ammonium sulfate = 26.42/molar mass of (NH4)2SO4
                                             =   26.42/132.14 = 0.19 mole.

Molarity = moles of ammonium sulfate/volume of solution
             =                0.19/50x10^-3
             =                    3.8M