Nitrates and phosphates are important soil minerals - Leaving Cert Agricultural Science - Question f - 2019
Question f
Nitrates and phosphates are important soil minerals.
In the case of each:
(i) Describe the test used to show the presence of the mineral.
(ii) Describe the colour ... show full transcript
Worked Solution & Example Answer:Nitrates and phosphates are important soil minerals - Leaving Cert Agricultural Science - Question f - 2019
Step 1
Describe the test used to show the presence of nitrates.
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Answer
To test for the presence of nitrates, one can use either diphenylamine or iron sulfate combined with sulfuric acid (H₂SO₄). Diphenylamine reacts with nitrates in an acidic medium, forming a colored complex.
Step 2
Describe the test used to show the presence of phosphates.
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Answer
For phosphates, the test involves using ammonium molybdate in the presence of nitric acid (HNO₃). This combination reacts with phosphates to indicate their presence.
Step 3
Describe the colour change that indicates a positive result for the presence of nitrates.
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Answer
A positive result for nitrates is indicated by a blue color with diphenylamine or a brown ring produced when using iron sulfate.
Step 4
Describe the colour change that indicates a positive result for the presence of phosphates.
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Answer
The presence of phosphates is indicated by a yellow color change after the addition of ammonium molybdate.
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