How many moles of solute are in 250 mL of 2.0M $CaCl_2$ ? How many grams of $CaCl_2$ is this?

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Answer 1 · 2016-08-04T20:21:34

The solution contains 0.50 mol or 55 g of $"CaCl"_2$ .

Moles of $"CaCl"_2$

You know there are 2.0 mol of $"CaCl"_2$ in 1 L of solution.

In 250 mL of solution there are

$"0.250" cancel("L soln") × "2.0 mol CaCl"_2/(1 cancel("L soln")) = "0.50 mol CaCl"_2$

Mass of $"CaCl"_2$

The mass of 1 mol of $"CaCl"_2$ is

$"(40.08 + 2 × 35.45) g" = "(40.08 + 70.90) g" = "110.98 g"$ .

So the mass of $"0.50 mol of CaCl"_2$ is

$"0.50" cancel("mol CaCl"_2) × "110.98 g CaCl"_2/(1 cancel("mol CaCl"_2)) = "55 g CaCl"_2$

How many moles of solute are in 250 mL of 2.0M CaCl_2CaCl_2? How many grams of CaCl_2CaCl_2 is this?