Question

What is the molarity of a solution that contains 45 mEq Ca“ per liter?

Answer 1

0.0225 M

Step-by-step explanation:

In one liter of this solution, there are 45 mEq of Ca⁺².

1 mEq of Ca⁺² is equal to 20 mg of Ca⁺. We know this by dividing its molar mass (40) by the charge of the ion (2).

Meaning that 45 mEq of Ca⁺² is equal to (45 * 20) 900 mg of Ca⁺².

Now we convert 900 mg of Ca⁺² into moles, using its molar mass:

• 900 mg / 1000 = 0.9 g

• 0.9 g Ca⁺² ÷ 40 g/mol = 0.0225 mol Ca⁺²

Finally we calculate the molarity of the solution:

• Molarity = moles / liters

• 0.0225 mol / 1 L = 0.0225 M