UNIT OVERVIEW

Acids and bases are part of everyday life. Citric acid gives oranges their sour taste. Sodium hydroxide is used in drain cleaners. Antacids neutralise stomach acid. Fertilisers affect soil pH. Understanding how these substances react, how we measure their strength, and how we determine their concentrations is important for careers in medicine, agriculture, water treatment, and industry.

This unit builds on your Grade 11 knowledge of acids and bases. You will learn why some salt solutions are acidic or basic, how blood maintains a stable pH, and how chemists use titrations to find unknown concentrations.

By the end of this unit, you will be able to:

• Write balanced equations for reactions of acids with metals, metal oxides, metal hydroxides, and metal carbonates
• Perform acid-base titration calculations
• Calculate pH from hydronium ion concentration and vice versa
• Use the relationship between $[H_3O^+]$, $[OH^-]$, and $K_w$
• Explain salt hydrolysis and predict whether a salt solution will be acidic, basic, or neutral
• Describe how buffer solutions resist changes in pH
• Conduct the prescribed experiment: titration of oxalic acid against sodium hydroxide

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