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Plants require trace metal nutrients, such as zinc, for healthy growth - Scottish Highers Chemistry - Question 10 - 2024
Question 10
Plants require trace metal nutrients, such as zinc, for healthy growth. Zinc ions are absorbed from soil through the plant roots. The zinc ion concentration in a so... show full transcript
Worked Solution & Example Answer:Plants require trace metal nutrients, such as zinc, for healthy growth - Scottish Highers Chemistry - Question 10 - 2024
Step 1
Explain fully why the flask was left for 24 hours, without a stopper.
Answer
Leaving the flask for 24 hours allows sufficient time for all of the zinc to react with the dilute sulfuric acid to form zinc sulfate. Without a stopper, hydrogen gas produced during the reaction can escape, preventing pressure build-up and ensuring the reaction proceeds to completion.
Step 2
Explain why the student should use deionised water or distilled water, rather than tap water, when preparing the stock solution.
Answer
Deionised or distilled water should be used to avoid introducing zinc ions, impurities, or other metal salts that may be present in tap water, which could interfere with the chemical reactions and the accuracy of the solutions prepared.
Step 3
Step 4
Calculate the concentration, in mg l^-1, of the solution prepared by transferring 10 cm^3 of the 1 g l^-1 stock solution to a 1000 cm^3 standard flask and making up to the mark.
Answer
To calculate the concentration:
-
Start with the stock concentration: 1 g l^-1, which is equal to 1000 mg l^-1.
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Use the dilution formula:
where:
- = initial concentration (1000 mg l^-1)
- = initial volume (10 cm^3)
- = final concentration (unknown)
- = final volume (1000 cm^3)
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Rearranging gives:
-
Therefore, the concentration of the diluted solution is 10 mg l^-1.
Step 5
Determine the concentration, in mg l^-1, of zinc ions in the solution.
Answer
To determine the concentration from the absorbance data and the given graph, it is essential to find the corresponding concentration for an absorbance of 0.3. Based on the plotted results, the concentration should be between 4 and 5 mg l^-1. A best fit line can be used to approximate the concentration more accurately within this range.