Question

what is the molarity of a solution of potassium dichromate (k2cr2o7) if 187 grams are dissolved in 250 ml?

Answer 1

Answer:
Molarity = 2.54 mol.L⁻¹

Solution:
Molarity is the amount of solute dissolved per unit volume of solution. It is expressed as,

Molarity = Moles / Volume of Solution ----- (1)

Data Given;
Mass = 187 g

Volume = 250 mL = 0.25 L

First calculate Moles for given mass as,

Moles = Mass / M.mass

Moles = 187 g / 294.185 g.mol⁻¹

Moles = 0.6356 mol

Now, putting value of Moles and Volume in eq. 1,

Molarity = 0.6356 mol ÷ 0.25 L

Molarity = 2.54 mol.L⁻¹