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
32 g Na2​CO3​V = 500 mL

32 g of Na2CO3 (M = 105.99 g/mol) is dissolved in water to make 500 mL of solution. Find the molarity c.

m = 32 gM = 105.99 g/molV = 500 mL
c = mol/L
2.Easy
1000 mLc = 0.2 mol/L

What mass m of KMnO4 (M = 158.03 g/mol) do you need to make 1000 mL of a 0.2 mol/L solution?

V = 1000 mLc = 0.2 mol/LM = 158.03 g/mol
m = g
3.Medium
5 mol/LV1​0.05 mol/L1000 mL

You need 1000 mL of 0.05 mol/L solution and have a 5 mol/L stock solution. How much water Vwater do you add to the stock solution?

c1 = 5 mol/Lc2 = 0.05 mol/LV2 = 1000 mL
Vwater = mL
4.Medium
2.5 mol/LV1​ = ?0.3 mol/L250 mL

You need 250 mL of 0.3 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 = 0.3 mol/LV2 = 250 mL
V1 = mL
5.Hard
0.2 mol/L50 mL0.1 mol/L500 mLc = ?550 mL

50 mL of a 0.2 mol/L solution is mixed with 500 mL of a 0.1 mol/L solution of the same substance. Find the concentration c of the mixture (volumes are additive).

c1 = 0.2 mol/LV1 = 50 mLc2 = 0.1 mol/LV2 = 500 mL
c = mol/L
6.Hard
2 mol/L150 mL0.6 mol/L400 mLc = ?550 mL

150 mL of a 2 mol/L solution is mixed with 400 mL of a 0.6 mol/L solution of the same substance. Find the concentration c of the mixture (volumes are additive).

c1 = 2 mol/LV1 = 150 mLc2 = 0.6 mol/LV2 = 400 mL
c = mol/L

Answer key

  1. 1. c = 0.6038 mol/L
  2. 2. m = 31.61 g
  3. 3. Vwater = 990 mL
  4. 4. V1 = 30 mL
  5. 5. c = 0.1091 mol/L
  6. 6. c = 0.9818 mol/L

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