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Science · Grades 10–12

Concentration and dilution: avoid common errors

Molar concentration uses the total final solution volume in litres.

Make a worksheet

Understand the idea

Use solution volume

Molar concentration uses the total final solution volume in litres.

Track solute amount

Dilution with solvent conserves the solute amount when there is no reaction or loss.

Examples and reasoning

For c = n/V in mol/L, which V is required?

final solution volume in litres

final solution volume in litres

Convert 250 mL to litres.

250 ÷ 1000 = 0.25

0.25

Check your understanding

  1. A solution contains 0.60 mol in 2.0 L. Find its concentration in mol/L.

  2. A 0.50 mol/L solution has volume 0.40 L. How many moles of solute are present?

  3. Solvent is added without solute loss. What stays constant?

    1. concentration
    2. amount of solute
    3. solution volume
    4. mass of solvent

  4. A solution volume doubles during dilution. Its concentration becomes

    1. twice the original value
    2. zero in every case
    3. half the original value
    4. unchanged

Answers and marking notes

Answers and marking notes
  1. 0.3

    0.60 ÷ 2.0 = 0.30

  2. 0.2

    0.50 × 0.40 = 0.20

  3. amount of solute

    amount of solute

  4. half the original value

    half the original value

Further reading and review references

These are reference links, not copied exercises, institutional endorsement or proof of independent review.

Learning preview · teacher review required. Grade bands are approximate, not official curriculum alignment.