A technician treats a sample of waste sulfuric acid by adding zinc carbonate powder in 0.50 g portions. After each addition, the technician waits until the reaction has stopped and then records the pH and the total volume of gas produced.
| Total mass of zinc carbonate added in g\mathrm{g}g | pH | Total volume of gas in cm3\mathrm{cm^3}cm3 |
|---|---|---|
| 0.00 | 1.0 | 0 |
| 0.50 | 1.1 | 96 |
| 1.00 | 1.3 | 192 |
| 1.50 | 1.7 | 288 |
| 2.00 | 7.0 | 360 |
| 2.50 | 7.0 | 360 |
At total masses of 2.00 g and 2.50 g, some solid remains. Zinc forms Zn²⁺ ions and sulfate ions are SO₄²⁻.
Describe a test the technician could do to identify the gas. Give the result of the test.
Describe and explain the patterns in the pH and the total volume of gas as more zinc carbonate is added.
Complete the balanced symbol equation for the reaction.
ZnCO₃ + H₂SO₄ → ...... + ...... + ......
The technician must neutralise another sample of sulfuric acid without producing a gas. The available solids are zinc and zinc oxide.
Name the solid the technician should use. Explain your answer.
112 exam-style questions on OCR GCSE Chemistry 3.3 Types of chemical reactions, covering 3.3.1 Oxidation and reduction in terms of oxygen, 3.3.2 Acids, alkalis and neutralisation, 3.3.3 The pH scale and measuring pH, 3.3.4 Oxidation and reduction in terms of electrons, 3.3.5 Dilute and concentrated, weak and strong acids, and 3.3.6 Hydrogen ion concentration and pH. Each one has a worked solution and a mark scheme showing where the marks go.