Answer to Question #175140 in Chemistry for Ally

Question

What is the mass in grams of potassium ion K+

(30.0 g/mol) in 25.0 g of potassium 

sulfate (K2SO4)?

Answer 1

Solution:

The molecular weight of potassium ion (K⁺) is 39.10 g/mol (not 30.0 g/mol)

K₂SO₄ → 2K⁺ + SO₄^2-

(25.0 g K₂SO₄) × (1 mol K₂SO₄ / 174.26 g K₂SO₄) × (2 mol K⁺ / 1 mol K₂SO₄) × (39.10 g K⁺ / 1 mol K⁺) = 11.2188 g K⁺ = 11.2 g K⁺

Mass of K⁺ = 11.2 g

OR (another solution path):

%K⁺ = (2 × Molar mass of K⁺ × 100%) / Molar mass of K₂SO₄

%K⁺ = (2 × 39.10 g mol^-1 × 100%) / 174.26 g mol^-1 = 44.88%

Mass of K⁺ = (%K⁺ × Mass of K₂SO₄) / 100%

Mass of K⁺ = (44.88% × 25.0 g) / 100% = 11.22 g = 11.2 g

Mass of K⁺ = 11.2 g

Answer: The mass of potassium ion (K⁺) is 11.2 g.