The student plans to conduct a spectrophotometric analysis to determine the concentration of Cu2+(aq) in a solution. The solutio
n has a small amount of Co(NO3)2 (aq) present as a contaminant. The student is given a diagram below, which shows the absorbance curves for aqueous solutions of Co2+ (aq) and Cu2+ (aq)
c. The spectrophotometer available to the student has a wavelength range of 400 nm to 700 nm. What wavelength should the student use to minimize the interference from the presence of the Co2+ (aq)?
c. The spectrophotometer available to the student has a wavelength range of 400 nm to 700 nm. What wavelength should the student use to minimize the interference from the presence of the Co2+ (aq)?
1 answer:
Answer:
The wavelength the student should use is 700 nm.
Explanation:
Attached below you can find the diagram I found for this question elsewhere.
Because the idea is to minimize the interference of the Co⁺²(aq) species, we should <u>choose a wavelength in which its absorbance is minimum</u>.
At 400 nm Co⁺²(aq) shows no absorbance, however neither does Cu⁺²(aq). While at 700 nm Co⁺²(aq) shows no absorbance and Cu⁺²(aq) does.
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Explanation:
where,
= energy of
orbit
n = number of orbit
Z = atomic number
a) Energy change due to transition from n = 1 to n = ∞ ,hydrogen atom .
Z = 1
Energy of n = 1 in an hydrogen like atom:
Energy of n = ∞ in an hydrogen like atom:
Let energy change be E for 1 atom.
Energy for 1 mole = E'
The energy required to remove the electron in the ground state is 1,312.17 kJ/mol.
b) Energy change due to transition from n = 1 to n = ∞ , atom .
Z = 5
Energy of n = 1 in an hydrogen like atom:
Energy of n = ∞ in an hydrogen like atom:
Let energy change be E.
Energy for 1 mole = E'
The energy required to remove the electron in the ground state is 32,804.31 kJ/mol.
c) Energy change due to transition from n = 1 to n = ∞ ,atom .
Z = 3
Energy of n = 1 in an hydrogen like atom:
Energy of n = ∞ in an hydrogen like atom:
Let energy change be E.
Energy for 1 mole = E'
The energy required to remove the electron in the ground state is 11,809.55 kJ/mol.
d) Energy change due to transition from n = 1 to n = ∞ ,atom .
Z = 25
Energy of n = 1 in an hydrogen like atom:
Energy of n = ∞ in an hydrogen like atom:
Let energy change be E.
Energy for 1 mole = E'
The energy required to remove the electron in the ground state is 820,107.88 kJ/mol.