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
100 mLc = 0.15 mol/L

What mass m of NaOH (M = 40 g/mol) do you need to make 100 mL of a 0.15 mol/L solution?

V = 100 mLc = 0.15 mol/LM = 40 g/mol
m = g
2.Easy
18 g CaCl2​V = 500 mL

18 g of CaCl2 (M = 110.98 g/mol) is dissolved in water to make 500 mL of solution. Find the molarity c.

m = 18 gM = 110.98 g/molV = 500 mL
c = mol/L
3.Medium
2.5 mol/LV1​ = ?0.2 mol/L250 mL

You need 250 mL of 0.2 mol/L solution and have a 2.5 mol/L stock solution. What volume V1 of stock solution do you need?

c1 = 2.5 mol/Lc2 = 0.2 mol/LV2 = 250 mL
V1 = mL
4.Medium
3 mol/LV1​0.4 mol/L1000 mL

You need 1000 mL of 0.4 mol/L solution and have a 3 mol/L stock solution. How much water Vwater do you add to the stock solution?

c1 = 3 mol/Lc2 = 0.4 mol/LV2 = 1000 mL
Vwater = mL
5.Hard
1.5 mol/L100 mL3 mol/L200 mLc = ?300 mL

100 mL of a 1.5 mol/L solution is mixed with 200 mL of a 3 mol/L solution of the same substance. Find the concentration c of the mixture (volumes are additive).

c1 = 1.5 mol/LV1 = 100 mLc2 = 3 mol/LV2 = 200 mL
c = mol/L
6.Hard
0.4 mol/L150 mL1.2 mol/L500 mLc = ?650 mL

150 mL of a 0.4 mol/L solution is mixed with 500 mL of a 1.2 mol/L solution of the same substance. Find the concentration c of the mixture (volumes are additive).

c1 = 0.4 mol/LV1 = 150 mLc2 = 1.2 mol/LV2 = 500 mL
c = mol/L

Answer key

  1. 1. m = 0.6 g
  2. 2. c = 0.3244 mol/L
  3. 3. V1 = 20 mL
  4. 4. Vwater = 866.7 mL
  5. 5. c = 2.5 mol/L
  6. 6. c = 1.015 mol/L

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