Science Project Summary:

Examining the effect of acidity and alkalinity on bacteria growth inhibition

Featured science projectScience project video Intermediate 6 < 1 week $50-$100 Readily available [+] More info
Difficulty: Intermediate 6
Cost ($): 50
Time required:
Preparation will require one day, while observation and recording of data will be carried out over a period of three days
Availability of materials:
Easily found
Safety concerns:

The bacteria should be destroyed with bleach before it is disposed of. Gloves and protective eyewear must be worn when handling the acid and alkali.

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Abstract:
The objective of this science fair projectis to investigate the effect of acidity and alkalinity on bacterial growth. This will be determined through the use of different concentrations of hydrochloric acid and sodium hydroxide, and measuring the size of the respective inhibition zones in samples of E. coli bacteria.
Procedure preview:
1.    The independent variables in this science fair project are the concentration of sodium hydroxide (alkaline) and hydrochloric acid (acid) – 5%, 10%, 15% and 20%. The dependent variable is the size of inhibition zone (area free of bacteria), which is determined by measuring the diameter of the area using a ruler. The constants (control variables) are the temperature of the room, the amount of sunlight and the ingredients used to make the agar in the Petri dishes. 2.    Use the marker pen to label eight Petri dishes that were prepared with agar as acid 5%, acid 10%, acid 15%, .....