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
19.5 g Na2​CO3​V = 750 mL

19.5 g of Na2CO3 (M = 105.99 g/mol) is dissolved in water to make 750 mL of solution. Find the molarity c.

m = 19.5 gM = 105.99 g/molV = 750 mL
c = mol/L
2.Easy
11 g NaOHV = 100 mL

11 g of NaOH (M = 40 g/mol) is dissolved in water to make 100 mL of solution. Find the molarity c.

m = 11 gM = 40 g/molV = 100 mL
c = mol/L
3.Medium
3 mol/LV1​ = ?0.5 mol/L100 mL

You need 100 mL of 0.5 mol/L solution and have a 3 mol/L stock solution. What volume V1 of stock solution do you need?

c1 = 3 mol/Lc2 = 0.5 mol/LV2 = 100 mL
V1 = mL
4.Medium
2.5 mol/LV1​0.1 mol/L500 mL

You need 500 mL of 0.1 mol/L solution and have a 2.5 mol/L stock solution. How much water Vwater do you add to the stock solution?

c1 = 2.5 mol/Lc2 = 0.1 mol/LV2 = 500 mL
Vwater = mL
5.Hard
1 mol/L150 mL0.05 mol/L500 mLc = ?650 mL

150 mL of a 1 mol/L solution is mixed with 500 mL of a 0.05 mol/L solution of the same substance. Find the concentration c of the mixture (volumes are additive).

c1 = 1 mol/LV1 = 150 mLc2 = 0.05 mol/LV2 = 500 mL
c = mol/L
6.Hard
0.5 mol/L50 mL0.75 mol/L200 mLc = ?250 mL

50 mL of a 0.5 mol/L solution is mixed with 200 mL of a 0.75 mol/L solution of the same substance. Find the concentration c of the mixture (volumes are additive).

c1 = 0.5 mol/LV1 = 50 mLc2 = 0.75 mol/LV2 = 200 mL
c = mol/L

Answer key

  1. 1. c = 0.2453 mol/L
  2. 2. c = 2.75 mol/L
  3. 3. V1 = 16.67 mL
  4. 4. Vwater = 480 mL
  5. 5. c = 0.2692 mol/L
  6. 6. c = 0.7 mol/L

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