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.
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%, .....
View science project