Concentration
\( c = \frac{n}{V} \)
Unit Warning
Volume MUST be in dm³ (not cm³). To convert: divide cm³ by 1000.
Standard Solutions & Dilutions
Standard Solution: A solution of accurately known concentration.
Dilutions: When you add water, moles stay the same but volume increases. Use:
Titration Calculation
Problem: 25.0 cm³ of 0.100 mol dm⁻³ NaOH is neutralized by 20.0 cm³ of HCl. Calculate the concentration of HCl.
\( NaOH + HCl \rightarrow NaCl + H_2O \) (1:1 ratio)
1. Moles of NaOH: \( n = c \times V = 0.100 \times 0.0250 = 0.00250 \text{ mol} \)
2. Moles of HCl: (1:1 ratio) = 0.00250 mol
3. Concentration of HCl:
\( c = \frac{0.00250}{0.0200} = 0.125 \text{ mol dm}^{-3} \)