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A blue solution of copper(II) sulfate was investigated using colourimetry - HSC - SSCE Chemistry - Question 16 - 2022 - Paper 1
Question 16
A blue solution of copper(II) sulfate was investigated using colourimetry. Orange light (λ = 630 nm) was used and the pathlength was 1.00 cm. Which change would res... show full transcript
Worked Solution & Example Answer:A blue solution of copper(II) sulfate was investigated using colourimetry - HSC - SSCE Chemistry - Question 16 - 2022 - Paper 1
Step 1
Using blue light (λ = 450 nm)
Answer
Using blue light instead of orange light would result in a higher absorbance value because blue light is absorbed more strongly by the blue copper(II) sulfate solution. The absorbance of a solution is influenced by the wavelength of the light used; shorter wavelengths (like blue) have higher absorbance for this type of solution compared to longer wavelengths (like orange).
Step 2
Setting the pathlength to 2.00 cm
Answer
Increasing the pathlength from 1.00 cm to 2.00 cm will also increase the absorbance due to the Beer-Lambert Law, which states that absorbance is directly proportional to pathlength. Thus, a longer pathlength allows more light to interact with the solution, leading to higher absorbance.