“Acids, Bases and Salts: Beyond the Textbook” is available to Standard subscribers.
Why does the pH scale go in steps of ten? Why is vinegar a weak acid and hydrochloric acid a strong one, when both turn litmus red? How does a chemist find the strength of an unknown alkali with a burette? In this course you read further, solve problems on pH, dilution and titration, and then take a timed challenge.
3Lessons7Problems2Python Labs1Question Set1Mock Test
Extended reading: why the pH scale is a logarithm: pH is minus the logarithm of the hydrogen ion concentration, so one step of pH is a factor of ten. A solution of pH 3 has a hundred times as many hydrogen ions as one of pH 5.
Extended reading: strong and weak acids, and titration: A strong acid ionises fully in water and a weak acid only a little, so at the same concentration a weak acid has a higher pH. In a titration, we find the strength of one solution from the volume of another that just neutralises it.
Extended reading: finding the water in a crystal: The number of water molecules in a hydrated salt, the x in a formula such as CuSO4·xH2O, is found by weighing. Heat the crystals to constant mass, find the mass of water lost, change both masses to moles, and divide.
The chapter itself stays free
This is an extra course for Acids, Bases and Salts. Its main courses are open to everyone: