An environmental scientist measures the pH of water samples near a coal-fired power station.
The table shows the results.
| Water sample | pH |
|---|---|
| rain water | 4.0 |
| lake water | 5.0 |
| spring water | 7.0 |
| factory waste water | 2.0 |
State how the pH of a solution changes as the concentration of hydrogen ions increases.
Determine how many times greater the hydrogen ion concentration is in the rain water than in the spring water.
A 10.0 cm3\mathrm{cm^{3}}cm3 sample of the factory waste water is diluted with pure water to a total volume of 1000 cm3\mathrm{cm^{3}}cm3. Determine the pH of the diluted solution. Explain your answer.
Powdered limestone, CaCO3\mathrm{CaCO_{3}}CaCO3, is added to the lake to neutralise the acid.
Write the ionic equation for the reaction between calcium carbonate and hydrogen ions. Include state symbols.
The lake contains 2.0×109 dm32.0 \times 10^{9}\ \mathrm{dm^{3}}2.0×109 dm3 of water. The concentration of hydrogen ions in the lake water is 1.0×10−5 mol dm−31.0 \times 10^{-5}\ \mathrm{mol\,dm^{-3}}1.0×10−5 moldm−3. Calculate the minimum mass of calcium carbonate needed to neutralise all the hydrogen ions in the lake. Give your answer in kilograms. Relative formula mass: CaCO3=100\mathrm{CaCO_{3}} = 100CaCO3=100
44 exam-style questions on Edexcel GCSE Chemistry 4.1 Acids, covering 4.1.1 Acids, alkalis and the pH scale, 4.1.2 Hydrogen ion concentration and pH, 4.1.3 Dilute and concentrated, weak and strong acids, 4.1.4 Bases, alkalis and the reactions of acids, 4.1.5 Chemical tests for hydrogen and carbon dioxide, 4.1.6 Neutralisation as a reaction of acids with bases, 4.1.7 Preparing soluble salts, and 4.1.8 Solubility rules and preparing insoluble salts. Each one has a worked solution and a mark scheme showing where the marks go.