Question

What mass (g) of calcium chloride, CaCl2, is needed to prepare 2.451 L of a 1.56 M solution

Answer 1

424 grams CaCl₂

Step-by-step explanation:

To find the mass of CaCl₂, you need to (1) calculate the moles (using the molarity ratio) and then (2) convert moles to grams (using the molar mass). The final answer should have 3 sig figs to match the given value with the least amount of sig figs.

(Step 1)

Molarity (M) = moles / volume (L)

1.56 M = moles / 2.451 L

3.82 = moles

(Step 2)

Molar Mass (CaCl₂): 40.078 g/mol + 2(35.453 g/mol)

Molar Mass (CaCl₂): 110.984 g/mol

3.82 moles CaCl₂ 110.984 g
---------------------------- x ------------------- = 424 grams CaCl₂
1 mole