[Cepheides]

Right now, I am completing a lab on the brominization of acetone. Here are all the steps I followed.

A. Measure 5 mL of 0.02 M Br2 solution in 10 mL graduated cylinder and add to a small beaker.  Add 10 mL of deionized water to the beaker.

B. Make 100 mL of a 4.0 M acetone solution by adding 30 mL acetone to a 100 mL volumetric flask and diluting to the mark.  Transfer solution to labeled beaker.

C. Make 100 mL of a 1.0 M H+ solution by partially filling a 100 mL volumetric flask with water then adding 25 mL of 4.0 M HCl.  Dilute to the mark and transfer to a labeled beaker.

D. Measure 5 mL of the prepared acetone solution and 5 mL of the prepared H+ solution into separate containers.  Add each of these solutions to the beaker containing Br2 and water.

After doing this and observing the reaction for 5 minutes, I noticed that the beaker gradually changed from yellow to transparent. Why does this happen?

[AWK]

Read the section of your manual on the halogenation of aldehydes and ketones.

[DrCMS]

The acetone has not become clear; the acetone was clear/colourless to begin with.  You have seen colour of the bromine solution change as a reaction happened.