2026 enrolment now open · IBDP & MYP Physics, taught 1-on-1 · 13+ years of specialist teaching · Average IB score 6.8 ·
2026 enrolment now open · IBDP & MYP Physics, taught 1-on-1 · 13+ years of specialist teaching · Average IB score 6.8 ·
Acids and bases are chemistry's opposing teams, and the pH scale is the scoreboard: 0–6 acidic, 7 neutral, 8–14 alkaline. Indicators — litmus, universal indicator, phenolphthalein — reveal where a solution sits. When acid meets base, neutralisation produces a salt and water, a reaction that names everything from antacid tablets to agricultural lime. You will learn the reliable reaction patterns (acid + metal, acid + carbonate, acid + base), how to name the salts they produce, and how neutralisation chemistry solves real problems from indigestion to acid rain.
Guiding Questions
?How can substances as different as lemon juice and oven cleaner be described by one scale?
?What really happens when an antacid tablet meets stomach acid?
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What the IB expects you to master
Classify solutions as acidic, neutral or alkaline using the pH scale (0–14).
Use indicators: litmus, universal indicator (with the colour spectrum) and phenolphthalein.
Name common laboratory acids (hydrochloric, sulfuric, nitric) and bases/alkalis (sodium hydroxide, calcium hydroxide, ammonia).
Describe neutralisation: acid + base → salt + water.
Predict products of acid + metal (salt + hydrogen) and acid + carbonate (salt + water + carbon dioxide).
Name salts from their parent acid: chlorides (HCl), sulfates (H₂SO₄), nitrates (HNO₃).
Apply neutralisation to real contexts: antacids, soil treatment, acid rain, bee stings.
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Key Formulas
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Exam Preparation & Topic Explanations
The three acid reaction patterns (Criterion A)
Three patterns answer nearly every acid question: acid + base → salt + water; acid + metal → salt + hydrogen; acid + carbonate → salt + water + carbon dioxide. Learn them as templates, then substitute the specific chemicals and name the salt from the acid.
Gas observations seal the marks: hydrogen pops with a lit splint, carbon dioxide turns limewater milky.
Pro Exam Strategy
The salt's surname comes from the acid: hydrochloric → chloride, sulfuric → sulfate, nitric → nitrate.
Alkali = a base that dissolves in water. All alkalis are bases; not all bases are alkalis.
Universal indicator gives a pH estimate; litmus only says acid or alkali. Choose the right tool for the question.
Real-world neutralisation contexts (antacids, soil lime, acid rain, toothpaste) are Criterion D favourites — link the chemistry to the impact.
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MCQ Practice
Q1.A solution turns universal indicator orange. Its approximate pH is:
1
4
7
10
Q2.The salt produced when magnesium reacts with sulfuric acid is:
Magnesium sulfide
Magnesium sulfate
Magnesium chloride
Magnesium nitrate
Q3.Farmers add lime (calcium hydroxide) to fields because:
