Factors affecting diffusion rates

Question 1

How can you investigate diffusion?

Answer 1

-using pH indicator phenolphthalein and dilute sodium hydroxide to make agar jelly

Question 2

What colour is phenolphthalein in alkaline vs acidic solutions?

Answer 2

-alkaline: pink
acidic: colourless

Question 3

Describe the base procedure

Answer 3

-fill beaker with dilute HCl acid
-use scalpel to cut few cubes of agar jelly and put into beaker of acid
-over time, the acid will diffuse into the agar jelly and neutralise the sodium hydroxide, making it colourless

Question 4

How do you investigate effect of SA?

Answer 4

-cut agar jelly into different sized cubes and calculate SA:V ratio
-time how long until each cube goes colourless in same HCL concentration.
-largest SA:V ratio go colourless fastest

Question 5

How do you investigate effect of temperature?

Answer 5

-prepare boiling tubes with same HCL concentrations and place in water baths of differing temperatures
-put equal sized jelly in each tube and time how long till each goes colourless
-highest temp go colourless fastest

Question 6

How do you investigate effect of concentration gradient?

Answer 6

-prepare test tubes with different HCl concentrations
-put equal sized jelly into tubes and time how long until they go colourless
-highest HCl conc go colourless fastest