The instrument that might be useful in characterising the equilibrium is spectrophotometer.
The use of spectrophotometer
Spectrophotometer is an instrument that is used to determine the reflectance of solutions which is affected by the amount of photons absorbed by the solution.
In a solution where by both the reactant and the product contain highly coloured nature of copper, the spectrophotometer can be used to characterise the equilibrium of copper.
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