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🧮 Concentration Worked Example

Concentration measures how many moles of solute are dissolved in 1 dm³ of solution:

c = n ÷ V (concentration = moles ÷ volume in dm³)

Question: 0.25 mol of NaOH is dissolved in 500 cm³ of water. Calculate the concentration in mol/dm³.

Step 1: Convert volume to dm³
500 cm³ ÷ 1000 = 0.5 dm³

Step 2: Apply the formula
c = n ÷ V = 0.25 ÷ 0.5 = 0.5 mol/dm³

Answer: 0.5 mol/dm³

Always convert cm³ to dm³ first by dividing by 1000. Forgetting this step is the most common mistake in concentration calculations.

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