EUTROPHICATION REVISION Q. Describe what fertilisers contain and explain the advantages and disadvantages of using them on farmland. KEYWORDS N__________ P__________ S__________ Y__________ A__________ R_____ O___ D__________ B__________ O__________ ____________

Potassium nitrate is a fertiliser. It is made by neutralisation. Look at the word equation for neutralisation. acid + alkalisalt + water Fertilisers such as potassium nitrate can cause eutrophication. Write down the names of the acid and alkali needed to make potassium nitrate and explain the problem of eutrophication caused by such fertilisers.

Level 3 Applies knowledge of acids and alkalis to name both chemicals required and the answer includes a comprehensive explanation of eutrophication which includes reference to bacteria using up oxygen. Quality of written communication does not impede communication of the science at this level.(5 – 6 marks) Level 2 Applies knowledge of acids and alkalis to name at least one chemical required and the answer includes an appreciation of increased growth of algae due to fertiliser in the water. Quality of written communication partly impedes communication of the science at this level.(3 – 4 marks) Level 1 Applies knowledge of acids and alkalis to name one correct chemical and/or a limited description of eutrophication is offered. Quality of written communication impedes communication of the science at this level.

Indicative scientific points at level 3 may include: most of the points mentioned up to level 2 and reference to bacteria or decomposers using up oxygen. alkali is potassium hydroxide (KOH) or potassium oxide (K2O)and acid is nitric acid (HNO3). A comprehensive explanation of eutrophication but either no mention of chemicals used or both chemicals named incorrectly scores level 2 (4 marks). If one chemical correct then 5 marks. Indicative scientific points at levels 1 and 2 may include: Eutrophication involves run off increased fertiliser concentration in water algal bloom blocking off of sunlight to other plants other plants die At level 1, a limited explanation is likely to include reference to run off and the death of aquatic organisms Not reference to poisoning by fertilisers above level 1