Benedict's Test?

Question

Would a benedict's solution turn the SAME solution in 5 tubes different colors when heated... WHY

I have a question concerning it on a lab and I'm having a hard time thinking of an answer. I had the same solution turn five different colors, and I was wondering if it was just because of human error (maybe I got a little bit of a different solution in the buret.. or what)

Please help end this confusion.. thanks in advance.

Answer 1

To check on "human error" look at the test being performed correctly at the first site below:

Trace positives are usually green in color. Heavy positive is a large amount of brick-red solid.

There are several possible reasons why the five tubes did not look the same, but each is just a different version of "the reactions were not carried out the same."

The first is possible contamination of the tubes in which the reactions were run. Always use clean, dry tubes for each experiment.

The second reason is error in the measurement of the reacting solutions. How accurate was the 5 mL of Benedict's solution measured from the buret? Is it possible that one got 4.8 mL or another 5.2 mL? Were the "drops" used the same size? Could some have been bigger than others? Was the same pipet used for all? These are called errors in precision. They usually improve as the student's techniques get better.

The last is other changes in the reaction conditions. In this case were all five tubes heated exactly the same way (like in a boiling water bath) or was each tube heated individually (like over a Bunsen burner)? Were all five tubes heated for the exact same length of time?

Answer 2

I don't think it would. You must not have put the same amount into each test tube. That's really wierd that I saw this question, considering the fact that I used a Benedict Solution in my science class today lol. If it was the same solution they should have all been the same color.

Answer 3

You test tubes were probably not cleaned properly.