Osmosis RPA

Question 1

Method

Answer 1

1) Use a cork borer to cut out 5 potato cylinders with equal diameters
2) Trim the cylinders so they are all equal length (around 3cm)
3) Accurately measure the mass and length of each potato
4) measure 10 cm cubed of different concentrations of sugar/ salt solution into boiling tubes and label them as well as one with distilled water
5) Add one potato cylinder into each boiling tube and leave overnight
6) Remove the cylinders from the boiling tubes, pat dry with a paper towel and re measure their length and mass
7) Record measurements in a table then calculate percentage change for length and mass
8) plot 2 graphs- one showing mass against concentration and one showing length against concentration

Question 2

What is used to cut out 5 potato cylinders equal in diameter

Answer 2

Cork borer
(But they then need to be trimmed so that they’re equal in length (around 3cm long))

Question 3

How long do you leave the boiling tubes with the potato cylinder and solution in

Answer 3

Overnight (to allow osmosis to take place)

Question 4

Why pat potato cylinders dry with paper towel after removing from solution

Answer 4

Remove surface water which to prevent the mass from being higher in order to get a more accurate value

Question 5

Why use distilled water

Answer 5

Doesn’t contain any dissolved substances that could increase the concentration and effect osmosis

Question 6

Sources of error

Answer 6

Cylinders taken from different parts of the potato may have different water potentials effecting osmosis