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
200 mLc = 0.25 mol/L

What mass m of NaCl (M = 58.44 g/mol) do you need to make 200 mL of a 0.25 mol/L solution?

V = 200 mLc = 0.25 mol/LM = 58.44 g/mol
m = g
2.Easy
23 g CaCl2​V = 750 mL

23 g of CaCl2 (M = 110.98 g/mol) is dissolved in water to make 750 mL of solution. Find the molarity c.

m = 23 gM = 110.98 g/molV = 750 mL
c = mol/L
3.Medium
5 mol/LV1​0.3 mol/L250 mL

You need 250 mL of 0.3 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 = 0.3 mol/LV2 = 250 mL
Vwater = mL
4.Medium
5 mol/LV1​ = ?0.5 mol/L500 mL

You need 500 mL of 0.5 mol/L solution and have a 5 mol/L stock solution. What volume V1 of stock solution do you need?

c1 = 5 mol/Lc2 = 0.5 mol/LV2 = 500 mL
V1 = mL
5.Hard
0.2 mol/L100 mL0.3 mol/L50 mLc = ?150 mL

100 mL of a 0.2 mol/L solution is mixed with 50 mL of a 0.3 mol/L solution of the same substance. Find the concentration c of the mixture (volumes are additive).

c1 = 0.2 mol/LV1 = 100 mLc2 = 0.3 mol/LV2 = 50 mL
c = mol/L
6.Hard
1 mol/L250 mL2.5 mol/L400 mLc = ?650 mL

250 mL of a 1 mol/L solution is mixed with 400 mL of a 2.5 mol/L solution of the same substance. Find the concentration c of the mixture (volumes are additive).

c1 = 1 mol/LV1 = 250 mLc2 = 2.5 mol/LV2 = 400 mL
c = mol/L

Answer key

  1. 1. m = 2.922 g
  2. 2. c = 0.2763 mol/L
  3. 3. Vwater = 235 mL
  4. 4. V1 = 50 mL
  5. 5. c = 0.2333 mol/L
  6. 6. c = 1.923 mol/L

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