pag agar cubes

Question 1

what is this investigating

Answer 1

effect of surface area to volume ratio on diffusion

Question 2

outline method

Answer 2

• coloured agar (dilute NaOH and universal indicator makes purple) cut into cubes (eg 0.5x0.5x0.5, 1x1x1, 2x2x2)
• cubes into boiling tubes of higher conc HCl
• measure either: time taken for the acid to completely change the colour of the indicator in the agar blocks, or distance travelled into the block by the acid (shown by the change in colour of the indicator) in a given time period
• convert into rates

Question 3

limitations

Answer 3

• colour change is subjective

- organisms are usually not cube shaped

Question 4

how to improve accuracy

Answer 4

use more and smaller intervals of cube length