Answer to Question #117847 in Chemistry for Elle

Question

Calculate the number of grams in the following
5. 1.0 liter of a 5.0 M solution of KOH.

6. 5.0 liters of a 0.8 M solution of H 2 SO 4

Answer 1

Solution:

(1) Molarity = Moles of solute / litres of solution

(2) Moles of solute = Mass of solute / Molar mass of solute

Combining the expression (1) and (2) we get:

Molarity = (Mass of solute) / (Molar mass of solute × Liters of solution)

Therefore,

(3) Mass of solute = Molarity × Molar mass of solute × Liters of solution

a)

The molar mass of KOH is 56.11 g/mol

Using the expression (3) we calculate the number of grams of KOH:

Mass of KOH = (5.0 M × 56.11 g/mol × 1.0 L) = 280.55 g

m(KOH) = 280.55 g

Answer (a): The mass of KOH is 280.55 grams.

b)

The molar mass of H₂SO₄ is 98.08 g/mol

Using the expression (3) we calculate the number of grams of H₂SO₄:

Mass of H₂SO₄ = (0.8 M × 98.08 g/mol × 5.0 L) = 392.32 g

m(H₂SO₄) = 392.32 g

Answer (b): The mass of H₂SO₄ is 392.32 grams.