Percent-concentration problems. Density
Answers are for parents and teachers.
1
15 g of Li₂O is added to 185 g of water (Li₂O + H₂O → 2LiOH). Find the mass fraction (%) of LiOH (M(Li₂O) = 30, M(LiOH) = 24).
12
2
400 g of 5 % solution and 100 g of 30 % solution are mixed. What percent is the new solution?
10
3
How many grams of water must be added to 500 g of 36 % solution to make it 12 %?
1000
4
A 270 g solution has a density of 1.35 g/mL. What is its volume in mL?
200
5
Why is the mass of the solution less than the sum of the starting masses when sodium reacts with water?
Hydrogen escapes as a gas and its mass is subtracted from the solution.