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
14 g Na2​CO3​V = 250 mL

14 g of Na2CO3 (M = 105.99 g/mol) is dissolved in water to make 250 mL of solution. Find the molarity c.

m = 14 gM = 105.99 g/molV = 250 mL
c = mol/L
2.Easy
21.5 g KClV = 150 mL

21.5 g of KCl (M = 74.55 g/mol) is dissolved in water to make 150 mL of solution. Find the molarity c.

m = 21.5 gM = 74.55 g/molV = 150 mL
c = mol/L
3.Medium
1.5 mol/LV1​0.4 mol/L200 mL

You need 200 mL of 0.4 mol/L solution and have a 1.5 mol/L stock solution. How much water Vwater do you add to the stock solution?

c1 = 1.5 mol/Lc2 = 0.4 mol/LV2 = 200 mL
Vwater = mL
4.Medium
5 mol/LV1​ = ?0.25 mol/L500 mL

You need 500 mL of 0.25 mol/L solution and have a 5 mol/L stock solution. What volume V1 of stock solution do you need?

c1 = 5 mol/Lc2 = 0.25 mol/LV2 = 500 mL
V1 = mL
5.Hard
0.5 mol/L50 mL1.2 mol/L250 mLc = ?300 mL

50 mL of a 0.5 mol/L solution is mixed with 250 mL of a 1.2 mol/L solution of the same substance. Find the concentration c of the mixture (volumes are additive).

c1 = 0.5 mol/LV1 = 50 mLc2 = 1.2 mol/LV2 = 250 mL
c = mol/L
6.Hard
1 mol/L300 mL0.75 mol/L400 mLc = ?700 mL

300 mL of a 1 mol/L solution is mixed with 400 mL of a 0.75 mol/L solution of the same substance. Find the concentration c of the mixture (volumes are additive).

c1 = 1 mol/LV1 = 300 mLc2 = 0.75 mol/LV2 = 400 mL
c = mol/L

Answer key

  1. 1. c = 0.5284 mol/L
  2. 2. c = 1.923 mol/L
  3. 3. Vwater = 146.7 mL
  4. 4. V1 = 25 mL
  5. 5. c = 1.083 mol/L
  6. 6. c = 0.8571 mol/L

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