Neco 2023 Chemistry Question 2

Practice practical question 2 from the 2023 Neco Chemistry examination. This question covers Periodic Table .

Neco 2023 Chemistry Practical

Topic: Periodic Table

Question 2 NECO • 2023 • CHEMISTRY • practical

A student is investigating the concentration of magnesium ions in an unknown solution using a UV‑visible spectrophotometer at 285 nm. The Beer‑Lambert law applies and the absorbance is directly proportional to concentration, passing through the origin. The data obtained are shown below. | Standard solution (C, mol L⁻¹) | Absorbance (A) | |-------------------------------|----------------| | 0.20 | 0.120 | | 0.40 | 0.245 | | 0.60 | 0.368 | | 0.80 | 0.492 | The unknown solution gives an absorbance of 0.310.

( a )

Calculate the average slope (ΔA/ΔC) of the calibration curve using the four standard solutions.

( b )

Determine the concentration of Mg²⁺ in the unknown solution.

( c )

Suggest two possible sources of systematic error that could cause the calculated concentration to be higher than the true value.

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This is Neco 2023 Chemistry Question 2. It is one of the practical questions from the 2023 Neco Chemistry examination.

The question covers Periodic Table .

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