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The UV-visible spectrum of a solution of a certain compound is shown above - VCE - SSCE Chemistry - Question 3 - 2009 - Paper 1
Question 3
The UV-visible spectrum of a solution of a certain compound is shown above. Consider the following statements about this compound and its UV-visible spectrum. I Th... show full transcript
Worked Solution & Example Answer:The UV-visible spectrum of a solution of a certain compound is shown above - VCE - SSCE Chemistry - Question 3 - 2009 - Paper 1
Step 1
I The amount of light absorbed by a solution of this compound depends on its concentration.
Answer
This statement is true. According to Beer-Lambert Law, absorbance (A) is directly proportional to the concentration (c) of the solution, given by the formula: where ε is the molar absorptivity and l is the path length.
Step 2
II The amount of light absorbed by a solution of this compound depends on the wavelength of light used.
Answer
This statement is also true. Different wavelengths of light can be absorbed by different electronic transitions in a compound, leading to variations in absorbance at those wavelengths. The spectrum provided shows specific absorbance peaks corresponding to particular wavelengths.
Step 3
III The spectrum is a result of electrons falling back from higher to lower electronic energy levels.
Answer
This statement is accurate. The absorbance peaks are indicative of electronic transitions where electrons absorb energy and transition from a lower energy level to a higher one, subsequently falling back and emitting energy.
Step 4
IV The concentration of a solution of this compound can only be determined by UV-visible spectroscopy at 250 nm.
Answer
This statement is false. While UV-visible spectroscopy can be utilized at 250 nm, it is not the sole wavelength for concentration determination. Concentrations can be determined at various wavelengths where the compound displays absorbance.