Glucose is a simple sugar and an essential source of energy for living cells. It's normally a solid and is a common reagent in a chemistry laboratory. High school and college students frequently make glucose solutions, as glucose dissolves easily in water. This experiment will demonstrate the calculations needed to determine the concentration of a solution.
Choose the total mass of your glucose solution. Assume for this example that you wish to make 200 grams (g) of solution. The mass of the glucose and water in the solution will total 200g.
Establish the concentration of glucose in the solution. Assume that you wish to make a 10 percent glucose solution for this example. The concentration of the glucose solution will be the mass of the glucose divided by the mass of the solution.
Determine the mass of glucose you'll need based on the desired mass of the solution and concentration of glucose. You know that Mg/Ms = c where Mg is the mass of the glucose, Ms is the desired mass of the solution and c is the desired concentration of glucose. Mg/Ms = c, so Mg = (Ms)(c) = (200 g)(0.10) = 20g for this example. Measure out 20g of glucose with a scale.
Calculate the mass of the water for the glucose solution. The mass of the solution is 200g, and the mass of the glucose is 20g. The mass of the water is therefore 180g. Place the beaker on the scale and pour 180g of water into the beaker.
Add the 20g of glucose you measured out in Step 3 to the 180g of water you prepared in Step 4. Stir in the glucose until it's completely dissolved. The solution will have a total mass of 200g and a concentration of 20g /200g = 0.1 = 10 percent as required.