Re: How does soap get rid of bacteria?

What you're talking about is "Anti-bacterial" soap. Usually this is 
regular soap with a chemical substance to inhibit or kill bacteria, added to 
it. The most common of these anti-bacterial chemicals in soaps is 
Triclosan. These chemicals kill bacteria in a variety of ways. Some 
chemically poison the bacteria, some cause it's cell walls to rupture and 
thereby, kill the bacteria, and some interfere with some of it's chemical 
process by preventing the movement of sodium or inhibiting other 
pathways. 
A possible interesting project could be to test the effectiveness or 
different "anti-bacterial" soaps or test soaps against other household 
chemicals like laundry bleach, tabasco sauce (sounds silly but try it), or 
even over-the-counter antibiotics like Neosporin. Good luck.