AQA Jan 2010 Paper 5 Q9

Answers available below

areas outside the box will not be scanned for marking a state the electron configuration of a ti iii ion and that of a ti iv ion explain in terms of electron configurations and electron transitions why ti iii compounds are usually coloured but ti iv compounds are colourless marks extra space question continues on the next page turn over wmp jan chem areas outside the box will not be scanned for marking b transition metal ions and their complexes can often be identified from their colours for each of the following identify a complex ion responsible for the colour of the aqueous solution restrict your answers to complexes formed from the elements cr fe co and cu a deep blue solution formed in an excess of concentrated aqueous ammonia a green solution formed in an excess of aqueous sodium hydroxide a yellow green solution formed in an excess of concentrated hydrochloric acid marks c an experiment is carried out to investigate the rate of the autocatalysed reaction between aqueous potassium manganate vii and ethanedioate ions in an excess of dilute sulfuric acid when these reagents are mixed together the colour of the reaction mixture gradually fades the concentration of the manganate vii ions is recorded at different times using a spectrometer the temperature of the reaction mixture is constant c i give two reasons why the use of a spectrometer is the most appropriate method for measuring the concentration of the coloured ions in this experiment marks extra space wmp jan chem areas outside the box will not be scanned for marking c ii sketch a curve to show how you would expect the concentration of manganate vii ions to change with time until the colour has faded because the concentration has reached a very low value explain the shape of the curve marks extra space end of questions wmp jan chem

Show answer