Answer to Question #165505 in General Chemistry for Ralph

Question

Calculate the mass (in grams) of magnesium chloride (MgCl2) that would be needed to prepare 150 mL of a 20% by mass aqueous solution of the salt. The density of the solution is 1.1 g/mL.

Answer 1

Given the density of the solution = 1.1 gram/ ml

So the mass of 150 ml of aqua solution = 150 x density of the solution

 = 150 ml X 1.1 gram /ml

=165 grams

According to the given data,

Magnesium chloride present in the solution = 20% by mass of the solution

 =$\dfrac{Mass of solution \times 20}{100}$ gram

= $\dfrac{165 \times 20}{100}$ gram

 =33 grams

hence, mass of the magnesium chloride needed to prepare a solution of 20% of magnesium chloride by mass = 33 grams of magnesium chloride