Question

1. What is the concentration, in g/mL, of a solution made by dissolving 75.0 g of phosphoric acid in 50.0 mL of solution?
2. What mass of NaCl is needed to produce 500 mL of a 2.0 mol/L solution?
3. What is the molarity of a solution that contains 0.350 g of barium fluoride, BaF₂, in 0.50 L of solution?
4. What is the molar concentration of a solution containing 10.0 g of NaOH in 250 mL of solution?
5. What mass of silver nitrate, AgNO₃, is needed to make 0.50 L of a 0.10 mol/L solution?
6. What volume of 1.0 mol/L solution of CuS can be made from 23.9 g of CuS?
7. A 100 mL sample of a 6.0 mol/L solution of H₂SO₄ is diluted to a final volume of 500 mL. What is the concentration of the diluted solution?
8. What volume of a 6.0 M NaOH solution is needed to produce 3.0 L of a 0.1 M solution?
9. Explain the steps you would follow to make 500 mL of a 0.5 mol/L solution of sodium chloride (NaCl) in the lab.

Answer 1

$1.\space\space c=75/50=1.5\text{ g/mL}.\\ 2.\space\space m=2·0.5·23=23\text{ g}.\\ 3.\space\space c_m=0.350/(137+19·2)/0.5=0.004\text{ mol/L}.\\ 4.\space\space c_m=10/(23+16+1)/250=0.001\text{ mol/mL}.\\ 5.\space\space m=nM=0.1·0.5·(170)=8.5\text{ g}.\\ 6.\space\space V=23.9/(96)/1=0.5\text{ L}.\\ 7.\space\space c=6·0.1/0.5=1.2\text{ mol/L}.\\ 8.\space\space V=3·0.1/6=0.05\text{ L}.\\ 9.\space\space \text{1) Find the amount of substance: }n=0.5·0.5=0.25\text{ mol.}\\\space\space\space\space \text{ 2) Find the mass of NaCl: } m=nM=14.6\text{ g}. \\ \space\space\space\space\space\text{3) Dissolve 16.4 g of NaCl in 500 mL of water.}$