Colorimetry is a technique used to determine the concentration of a colored compound in a solution by measuring its absorbance of light at a specific wavelength. In this case, we will use colorimetry to determine the concentration of copper II ions in a water sample. Here's a step-by-step procedure:1. Prepare a series of copper II ion standards:To create a calibration curve, you'll need to prepare a series of standard solutions with known concentrations of copper II ions. You can do this by dissolving an appropriate amount of copper II sulfate in distilled water. For example, you can prepare 5 standards with concentrations of 1, 2, 4, 6, and 8 ppm parts per million .2. Complexation of copper II ions:Copper II ions in solution are not very colored, so it's necessary to form a colored complex with a suitable reagent. One common reagent used for this purpose is sodium diethyldithiocarbamate. Add a known volume of this reagent to each standard solution and the water sample. The copper II ions will form a colored complex with the reagent, which can be measured using colorimetry.3. Measure the absorbance of the standards and the sample:Using a colorimeter or a spectrophotometer, measure the absorbance of each standard solution and the water sample at the wavelength of maximum absorbance usually around 435 nm for the copper-diethyldithiocarbamate complex . Make sure to zero the instrument with a blank solution containing all reagents except copper before taking measurements.4. Create a calibration curve:Plot the absorbance values of the standard solutions against their respective concentrations on a graph. Draw a best-fit line or curve through the points. This is your calibration curve, which will be used to determine the concentration of copper II ions in the water sample.5. Determine the concentration of copper II ions in the sample:Find the absorbance value of the water sample on the y-axis of the calibration curve, and trace it horizontally until it intersects the best-fit line. From this intersection point, trace a vertical line down to the x-axis to find the corresponding concentration of copper II ions in the sample.6. Calculate the concentration of copper II ions in the original water sample:If you diluted the water sample before analysis, you'll need to multiply the concentration obtained from the calibration curve by the dilution factor to get the actual concentration of copper II ions in the original water sample.By following these steps, you can quantify the concentration of copper II ions in a water sample using colorimetry.