Diffusion

Question 1

What is the practical into investigating the rate of diffusion?

Answer 1

-fill section of visking tubing with starch + glucose solutions
-suspend tubing into boiling water for set time
-test water at reg intervals for presence of S+G
-results should indicate that G not S diffuses out

Question 2

What is the practical investigating the effect of SA:V on diffusion?

Answer 2

-coloured agar cut into equal dimension
-purple agar - dilute Na hydroxide solution + universal indicator
-cubes in boiling tubes - containing diffusion solution
-diffusion can be checked by colour change - as acid has higher molarity than Na hydrox
-time taken for acid to change colour of indicator in blocks
-graph - show rate of diffusion changes with SA:V of agar cubes

Question 3

What is visking tubing?

Answer 3

-non living partially permeable membrane made from cellulose
-pores in this are small enough to prevent passage of large molecules