A factory stores acidic wastewater in a lined containment basin.
The basin contains 2400 m3 of wastewater with a pH of 3. The maximum capacity of the basin is 20 000 m320\,000\,\mathrm{m^3}20000m3.
Workers will remove some of the wastewater and then add pure water, with a pH of 7, until the basin is full.
Assume that the acidity behaves like an unbuffered strong-acid solution.
Calculate the volume of wastewater that must be removed so that the pH of the contents of the full basin is 4.
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.