I think you are doing this excellent project from the Science Buddies website:http://www.sciencebuddies.org/science-f ... #procedure
The experimental procedure section suggests making a series of dilutions for a positive control. Starting with a 4% solution, you are supposed to dilute the sample in half, so you have 7 dilutions with the following concentrations of glucose 4%, 2%, 1%, 0.5%, 0.25%, 0.125% and 0.0625%.plus the negative control, which if pure water.
Here are the directions from the procedure:
Label seven cups 1–7.
Add 8 g of glucose to 200 mL water in cup #1 to make the 4% solution.
Add 100 mL of water to each of the six remaining cups (2–7).
Add 100 mL of the 4% solution to cup #2 to make a 2% solution.
Then add 100 mL of the 2% solution to cup #3 to make a 1% solution.
Let me describe the first dilution in detail to help you get started.
Your first cup will be 200 ml of water containing 8 grams of dissolved glucose
Your second cup is 100 ml of water
To make the first dilution, transfer 100 ml of cup 1 to cup 2 and mix well.
Cup 2 now contains ½ of the concentration of glucose compared to cup 1, or 2%. So you have made a one to two dilution.
Now repeat the procedure using 100 ml from cup 2 to transfer to the 100 ml of water in cup 3. Cup 3 now contains 1% glucose.
Does this help?