Analisi dell’acqua — PHYWE 10321

PrincipleA colorimetric test kit can be used to quantitatively determine the phosphate ion content in water samples.

The deeper the blue colour of the sample, the higher its phosphate content.

By comparing the colour with the colour scale on the comparator, the concentration can be read directly.

A water sample and a tap water sample are measured in this way and compared with one another.Tasks1.

Take a water sample from a body of water of your choice (e.g.

a stream, pond or near an agricultural field).2.

Carry out the colorimetric phosphate test on the water sample using the test kit and compare the results.3.

Repeat the measurement with a tap water sample as a control sample and to evaluate it against the reference value.Learning objectivePupils learn how to use a colorimetric test kit safely and correctly and how to read the measurements properly.

They understand the chemical principles behind phosphate detection via the formation of phosphomolybdenum blue and recognise the significance of phosphate as an environmental problem.

Furthermore, they explore the effects of excessive phosphate pollution on aquatic ecosystems – from algal growth and eutrophication to the ‘tipping’ of a lake – and learn about measures that help reduce phosphate inputs into water bodies.BenefitsStrong link to everyday life: pupils test real water samples from their immediate surroundings – everyday products such as cola or washing powder can also be tested for their phosphate contentEasy to use: the colorimetric test provides quick and reliable quantitative results without the need for complex laboratory equipmentInterdisciplinary: Combines chemistry, biology and environmental science in a real-world context