Molarity & dilution worksheet with answers

Free printable Molarity & dilution worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
15.5 g KClV = 750 mL

15.5 g of KCl (M = 74.55 g/mol) is dissolved in water to make 750 mL of solution. Find the molarity c.

m = 15.5 gM = 74.55 g/molV = 750 mL
c = mol/L
2.Easy
1000 mLc = 0.5 mol/L

What mass m of KNO3 (M = 101.1 g/mol) do you need to make 1000 mL of a 0.5 mol/L solution?

V = 1000 mLc = 0.5 mol/LM = 101.1 g/mol
m = g
3.Medium
3 mol/LV1​ = ?0.25 mol/L100 mL

You need 100 mL of 0.25 mol/L solution and have a 3 mol/L stock solution. What volume V1 of stock solution do you need?

c1 = 3 mol/Lc2 = 0.25 mol/LV2 = 100 mL
V1 = mL
4.Medium
0.5 mol/LV1​0.4 mol/L100 mL

You need 100 mL of 0.4 mol/L solution and have a 0.5 mol/L stock solution. How much water Vwater do you add to the stock solution?

c1 = 0.5 mol/Lc2 = 0.4 mol/LV2 = 100 mL
Vwater = mL
5.Hard
0.5 mol/L250 mL0.3 mol/L500 mLc = ?750 mL

250 mL of a 0.5 mol/L solution is mixed with 500 mL of a 0.3 mol/L solution of the same substance. Find the concentration c of the mixture (volumes are additive).

c1 = 0.5 mol/LV1 = 250 mLc2 = 0.3 mol/LV2 = 500 mL
c = mol/L
6.Hard
0.5 mol/L100 mL2.5 mol/L400 mLc = ?500 mL

100 mL of a 0.5 mol/L solution is mixed with 400 mL of a 2.5 mol/L solution of the same substance. Find the concentration c of the mixture (volumes are additive).

c1 = 0.5 mol/LV1 = 100 mLc2 = 2.5 mol/LV2 = 400 mL
c = mol/L

Answer key

  1. 1. c = 0.2772 mol/L
  2. 2. m = 50.55 g
  3. 3. V1 = 8.333 mL
  4. 4. Vwater = 20 mL
  5. 5. c = 0.3667 mol/L
  6. 6. c = 2.1 mol/L

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