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
25.5 g CaCl2​V = 100 mL

25.5 g of CaCl2 (M = 110.98 g/mol) is dissolved in water to make 100 mL of solution. Find the molarity c.

m = 25.5 gM = 110.98 g/molV = 100 mL
c = mol/L
2.Easy
40 g Na2​CO3​V = 500 mL

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

m = 40 gM = 105.99 g/molV = 500 mL
c = mol/L
3.Medium
1 mol/LV1​ = ?0.4 mol/L200 mL

You need 200 mL of 0.4 mol/L solution and have a 1 mol/L stock solution. What volume V1 of stock solution do you need?

c1 = 1 mol/Lc2 = 0.4 mol/LV2 = 200 mL
V1 = mL
4.Medium
1 mol/LV1​ = ?0.4 mol/L500 mL

You need 500 mL of 0.4 mol/L solution and have a 1 mol/L stock solution. What volume V1 of stock solution do you need?

c1 = 1 mol/Lc2 = 0.4 mol/LV2 = 500 mL
V1 = mL
5.Hard
0.8 mol/L200 mL0.75 mol/L50 mLc = ?250 mL

200 mL of a 0.8 mol/L solution is mixed with 50 mL of a 0.75 mol/L solution of the same substance. Find the concentration c of the mixture (volumes are additive).

c1 = 0.8 mol/LV1 = 200 mLc2 = 0.75 mol/LV2 = 50 mL
c = mol/L
6.Hard
1 mol/L300 mL0.3 mol/L400 mLc = ?700 mL

300 mL of a 1 mol/L solution is mixed with 400 mL of a 0.3 mol/L solution of the same substance. Find the concentration c of the mixture (volumes are additive).

c1 = 1 mol/LV1 = 300 mLc2 = 0.3 mol/LV2 = 400 mL
c = mol/L

Answer key

  1. 1. c = 2.298 mol/L
  2. 2. c = 0.7548 mol/L
  3. 3. V1 = 80 mL
  4. 4. V1 = 200 mL
  5. 5. c = 0.79 mol/L
  6. 6. c = 0.6 mol/L

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