An aqueous solution of 4.57 M H2SO4 has a density of 1.25 g/mL. Calculate the molality of this solution

The molality is 5.7 molal

Explanation:

Step 1: Data given

Molarity of H2SO4 = 4.57 M ( = 4.57 mol/L)

Density of the solution = 1.25 g/mL

Molar mass of H2SO4 = 98.09 g/mol

Step 2: Calculate mass of solution

Suppose we have 1L (= 1000 mL) of solution

Mass of the solution = 1.25 g/mL * 1000 mL

Mass of the solution = 1250 grams

Step 3: Calculate mass H2SO4

In 1L of a 4.57 M solution we have 4.57

Mass H2SO4 = moles H2SO4 * molar mass H2SO4

Mass H2SO4 = 4.57 moles * 98.09 g/mol

Mass H2SO4 = 448.3 grams

Step 4: Calculate mass solvent

Mass solvent = mass solution - mass H2SO4

Mass solvent = 1250 grams - 448.3 grams

Mass solvent = 801.7 grams

Step 5: Calculate molality

Molality = moles H2SO4 / mass solvent

Molality = 4.57 moles / 0.8017 kg

Molality = 5.7 molal

The molality is 5.7 molal

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