1. The pH scale

Available for over a year

In this episode, Dr Sunayana Bhargava and Tulela Pea define acids, alkalis and the pH scale. They look at the difference between strong, weak, concentrated and dilute acids. Suitable for: AQA, Edexcel, OCR. For more information on the pH scale, check out the BBC Bitesize website: https://www.bbc.co.uk/bitesize/guides/ztv2dxs/revision/1 Key learning objectives discussed in this episode include: - Acids produce hydrogen ions (H+) in aqueous solutions. - Aqueous solutions of alkalis contain hydroxide ions (OH–). - The pH scale, from 0 to 14, is a measure of the acidity or alkalinity of a solution and can be measured using universal indicator or a pH probe. - A solution with pH 7 is neutral. Aqueous solutions of acids have pH values of less than 7 and aqueous solutions of alkalis have pH values greater than 7. - In neutralisation reactions between an acid and an alkali, hydrogen ions react with hydroxide ions to produce water. - A strong acid is completely ionised in aqueous solution. Examples of strong acids are hydrochloric, nitric and sulfuric acids. - A weak acid is only partially ionised in aqueous solution. Examples of weak acids are ethanoic, citric and carbonic acids. - For a given concentration of aqueous solutions, the stronger an acid, the lower the pH. - As the pH decreases by one unit, the hydrogen ion concentration of the solution increases by a factor of 10. Presented by Dr Sunayana Bhargava and Tulela Pea ‘NNICK’ written and performed by Nick Romero Written and Produced by Julian Mayers Exec Producer: Chris Wilson A Yada-Yada Audio Production for BBC Bitesize and BBC Sounds