General Chemistry

Question

what is the molarity of a solution made by dissolving 12.5 grams of potassium chromate in enough water to form 225 ml of solution?

Then give the molarity for the cation.

Please include steps

Answer 1

The formula for potassium chromate is K₂Cr₂O₇ thus the molar mass is

(39×2) + (52×2) + (16×7) = 78 + 104 + 112 = 294

Number of moles of potassium chromate = 12.5/294 = 0.0425mol

Molarity of potassium chromate = number of moles/ number of liters of solution = 0.0425/0.225 =0.189 M

Since each molecule contains two potassium ions, Molarity of K⁺ is twice 0.189 M = 0.378 M