Required Practical 3:

Question 1

What is osmosis?

Answer 1

diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane

Question 2

How do you prepare the potatoes ?

Answer 2

1. peel potato ( as skin can effect osmosis )
2. using a cork borer to produce 3 cylinders of potato with the same diameter
3. use a scalpel to trim the cylinders to the same length of around 3cm
4. measure the length of each cylinder with a ruler and measure the mass of each cylinder using a balance.
5. place each cylinder into a test tube

Question 3

how do you calculate percentage change ?

Answer 3

change in value / original value multiplied by one hundred

Question 4

describe the graph that represents the % change in mass for the concentration of sugar solution.

Answer 4

the change in mass is inversely proportional to the concentration of sugar solution

Question 5

what do you do with the prepared potato cylinders ?

Answer 5

1. add 10cm^3 of a 0.5 molar sugar solution to the first test tube
2. add 10cm^3 of a 0.25 molar sugar solution to second test tube
3. add 10^3 of distilled water to the 3rd test tube
4. Leave over night, then roll them on a paper towel to remove surface water
5. re-measure the length and mass