Colorimetry is a technique used to determine the concentration of a colored substance in a solution by measuring the amount of light it absorbs. In this case, we will use colorimetry to determine the concentration of copper ions in the sample. Here's a step-by-step procedure:1. Prepare a series of standard solutions: To create a calibration curve, you'll need to prepare a series of standard solutions with known concentrations of copper ions. You can do this by dissolving a known amount of copper salt e.g., copper sulfate in a fixed volume of water. Prepare at least five different concentrations, including a blank solution with no copper ions.2. Complexation reaction: Copper ions in solution can form colored complexes with certain ligands. In this case, we can use a reagent like ammonia or a biuret reagent to form a colored complex with the copper ions. Add an equal volume of the chosen reagent to each standard solution and the unknown sample. Allow the reaction to proceed for a few minutes, so the colored complex forms completely.3. Measure absorbance: Using a colorimeter or a spectrophotometer, measure the absorbance of each standard solution and the unknown sample at the wavelength of maximum absorbance for the copper complex usually around 600-700 nm . Make sure to zero the instrument with the blank solution before taking measurements.4. Create a calibration curve: Plot the absorbance values of the standard solutions against their respective copper ion concentrations. The resulting graph should be a straight line, as described by the Beer-Lambert Law, which states that the absorbance of a solution is directly proportional to its concentration. Perform a linear regression to obtain the equation of the line y = mx + b , where y is the absorbance, x is the concentration, m is the slope, and b is the y-intercept.5. Determine the concentration of the unknown sample: Using the absorbance value of the unknown sample, substitute it into the equation obtained from the calibration curve to solve for the concentration x . This will give you the concentration of copper ions in the unknown sample.In summary, colorimetry relies on the principle that the absorbance of a colored solution is directly proportional to its concentration. By creating a calibration curve using standard solutions and measuring the absorbance of an unknown sample, you can determine the concentration of copper ions in the sample.