Copper sulfate (also spelled "sulphate") is a brilliant blue salt which readily dissolves in water. The solubility of copper sulfate is temperature-dependent, and increasing the water temperature encourages more salts to dissolve, resulting in increased concentrations. By using a solubility curve, which describes the relationship between temperature and the amount of salt that can be dissolved, you can create solution concentrations of choice without the risk of adding too much salt.
- Graduated cylinder
- Glass beaker
- Glass rod
Solubility curves may present the amount of water as a mass given in grams, and not a volume given in cubic centimeters or milliliters. Using the density of water, one cubic centimeter or one milliliter of pure water is equivalent to one gram of water.
Copper sulfate solutions are corrosive to many metals. Always use plastic or glass objects to stir the solution. If the solution spills on a metal surface, immediately wipe the spill using a paper towel.
Measure 100 ml of water in a graduated cylinder, and transfer approximately 80 ml of the water from the cylinder to the glass beaker.
Place a thermometer in the water in the beaker and measure the water's temperature.
Consult the solubility curve for copper sulfate (see link under "Resources" section below). Find the water temperature on the X axis of the graph. Read the maximum amount of salt that can be dissolved at this temperature from the Y axis. This amount of copper sulfate salt added to the water will form a saturated solution at this temperature. To dissolve more copper sulfate than this critical amount of salt, you will need to heat the water or add more water to the beaker.
Weigh the appropriate amount of copper sulfate using the scale. Add the copper sulfate crystals to the water in the beaker, stir briefly, and add the remaining water from the graduated cylinder to the beaker.
Stir the mixture of water and salts using a glass rod until all the crystals have dissolved to form a saturated copper sulfate solution.