Soap vs. Sanitizer

Laboratory Experiment

Why wash your hands?   Hand are the most

frequent transmission route for many types of infections.

  Pathogens may enter through the mouth, nose, or eyes.

  Proper hand hygiene is the easiest way to reduce infections.

How do you wash properly?   Scrub your hands with soap

and warm water for 20 seconds to 2 minutes.

  Scrubbing your hands physically removes dirt and grease, which wash away with the water

What about hand sanitizer?   When water is not available, hand sanitizer can be an

effective alternative.   The alcohol in hand sanitizer disrupts the coating on

bacteria and viruses.   Use enough sanitizer to keep your hands wet while

you rub for at least 30 seconds.

Soap vs. Sanitizer Experiment   Problem/Question:

  Which is more effective at reducing the amount of bacteria on hands: washing with soap or antibacterial sanitizer?

  Hypothesis & Prediction:   If washing with soap and water is more effective at reducing

the amount of bacteria on hands, then the soap treatment will show a greater reduction in bacterial growth than the sanitizer treatment.

Experimental Design   Independent/Manipulated Variable:

  Cleanser/Chemical   Dependent/Responding Variable:

  Bacterial growth   Treatments:

  Soap   Sanitizer

  Control:   No soap or sanitizer

  Analysis:   Compare percent reduction in bacterial growth

Methods   Label your Petri dish

  Group   #Treatment   Before/After

Before

After

Gro

up 1

Methods   How to sample:

Methods   Apply treatment for 30 seconds

Analysis   # Before - # After = Difference   Difference ÷ # Before = Reduction   Reduction x 100 = % Reduction

TREATMENT  Number of Bacterial Colonies  

Before   After   Difference   % Reduction  

Control 1  

Control 2  

Control Average:  

Soap 1  

Soap 2  

Soap Average:  

Sanitizer 1  

Sanitizer 2  

Sanitizer Average:  

Analysis   Sample results:

TREATMENT  Number of Bacterial Colonies  

Before   After   Difference   % Reduction  

Control 1   119 500 -381 -320%

Control 2   198 32 166 83.8%

Control Average:   -118%

Soap 1   100 68 32 32%

Soap 2   6 90 -84 -1400%

Soap Average:   -684%

Sanitizer 1   7 1 6 85.7%

Sanitizer 2   23 2 21 91.3%

Sanitizer Average:   88.5%

Expected ≈ 0

Expected > 0