Question

2. A farmer suspects that his well water is being contaminated by phosphates and nitrates from fertilizer in his fields. What tests could be done to support his supposition? If the contamination did not come from fertilizer, what else might cause the contamination? 

3. Explain testing for halides in this experiment by relating observations to oxidation- reduction reactions.

Answer 1

2. We have to test if water is contaminated by phosphate and nitrate.

Both test strips and color disk test kits are available for nitrate and phosphate testing. Nitrate can also be measured with a digital meter.

Contaminants in rain, snow, and dry atmospheric fallout can be another reason for water contamination.

3. To explain halide testing by relating to oxidation-reduction reaction:

To explain it with the help of an example, Consider a reaction between one halogen—​chlorine, say iodine and chlorine.

Cl2 +2 I− -----> 2 Cl−+ I2

Here, The iodide ions lose electrons, i.e,  they are oxidized to iodide molecules and the chlorine molecules gain electrons i.e, they are reduced to chloride molecules. This is a redox reaction in which chlorine is acting as an oxidizing agent.