“How to Test for Sugar”
by
Laura Franks, Abby, and Jenna
WilsonSchool, LauderdaleCounty
When conducting a test for sugar, you will need the following materials: goggles to protect your eyes, an apron to protect your clothing, Benedict’s solution (this is what Benedict’s looks like close up), test tubes labeled DW, Sugar Solution, A and B;a test tube rack, a test tube clamp, a water bath, a stopwatch or timer, pipettes, distilled water, sugar solution, unknown substances A and unknown substance B.
CAUTION: Benedict’s may damage your eyes, and it may stain your skin and clothing. You must report any accident concerning Benedict’s to your teacher!
To begin a test for sugar, you should first establish a “control.” For this control you will need to place about 30 drops of distilled water into the test tube labeled DW. Because you already know that distilled water does not have anything in it but water, then you know it should test negative (-) for sugar.
Next, place about thirty drops of the sugar solution into the test tube labeled sugar solution. Because you already know that sugar solution contains sugar, then you know it should test positive (+) for sugar.
Next, using the Benedict’s solution, place 10 drops of Benedict’s into the distilled water. Benedict’s alone appears to be a pale bluish color.
Continue with the Benedict’s solution by placing 10 drops of Benedict’s into the test tube labeled sugar solution.
In order for the Benedict’s to work as an indicator, it must be heated. Using the test tube clamp, place the two test tubes into the hot water bath for one minute. After one minute, use the test tube clamp to remove the hot test tubes.
Notice if there has been any color change. The test tube with distilled water is still blue. What do you think that means? Because the sample remains blue, that indicates that the sample is negative for sugar. The test tube with sugar solution has turned orange-red. What do you think that means? Because the sample turned orange-red, that indicates that the sugar solution is positive for sugar.
Now that you have established a control, you are ready to test unknown solutions A and B.
First place 30 drops of Unknown Solution A into the test tube labeled A. Then place 30 drops of Unknown Solution B into test tube labeled B. Now, use the Benedicts in each of the Unknown Solutions to test for sugar. Remember Benedicts must be heated in order for it to work as an indicator.
After placing test tubes A and B into the water bath for one minute, remove them and observe the results.
The result for Unknown Solution A was no color change. The result for Unknown Solution B was orange. Using what you learned from the control set up, what does this data mean??????
Correct! Solution A is negative (-) for sugar and Solution B is positive (+) for sugar.
Now you know how to conduct a test for sugar.
Something to thing about… What do you think it would mean to get a green or a yellow as a result of the test???????????