Determining water potential by mass change

Question 1

potential control variables of potato experiment

Answer 1

temperature, type of potato

Question 2

Iv of experiment

Answer 2

concentration of NaCl

Question 3

DV of experiment

Answer 3

% change of mass

Question 4

Describe the set up of the test tubes

Answer 4

-6 boiling tubes labelled 0, 0.2, 0.4, 0.6, 0.8 and 1.0 mol dm-3
-place 30cm3 of distilled water in first tube
-place 30cm3 of appropriate salt solution in other tubes
-firmly stopper each tube

Question 5

Describe procedure

Answer 5

-use cork borer and scalpel to prepare 6 potato cylinders of 50mm long
-divide filter paper into 6 labelled sections and place cylinder onto each section
-record mass of each cylinder and place in appropriate test tube
-leave tubes for 45 mins
-remove cylinders and place on appropriate space
-blot each cylinder dry
-reweigh each cylinder and calculate mass change

Question 6

What results would you expect to see?

Answer 6

As NaCl concentration increases, potatoes lose mass more rapidly

Question 8

what happens when the potato reaches its isotonic point?

Answer 8

the movement of water into the cells is equal to the movement of water out of the cells

Question 9

Explain why the graph would show a negative correlation

Answer 9

-when the NaCl solution has a higher solute concentration than the potato, water moves out of the potato so it therefore loses mass