Answer to Question #251345 in General Chemistry for Shy

Question

Show your solution and provide units in your solution

1.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 1.1g/mL.

3. A solution is prepared by dissolving 20 mL of pure hydrogen peroxide (H2O2) in enough water to make 200 mL of solution.What is the concentration of the H2O2 solution?

Answer 1

1. Mass of solution=volume*Density

=1.1g/ml(150ml)=165g

Mass of MgCl₂=(20/100)*165g

=33g of MgCl₂

2.Concentration of pure hydrogen peroxide=42.404g/L

Molarity=(g/l)/(RFM)

=(42.404g/L)/34g

=1.2472M

M₁V₁=M₂V₂

20*1.2472=200M₂

M₂=(20*1.2472)/200

=0.1247M H₂O₂