Assignment:
Finding the concentration of potato cell sap
Planning
In my experiment I am going to vary my concentration using 2 morar salt solution mixing it with pure water
i know that in osmosis that water moves from one low concentration to a high concentration. If there is a low concentration the high concentration will move into it. I am going to use this to find the concentration of cell sap as when the different concentration on the outside effects the water concentration inside the potato and there for the overall mass of the potato. If doesn't change the mass of the potato this will show that the concentration hasn't changes
Apparatus
Test tube
Chokebore
Pipette
Measuring cylinder
Glass rod
Tweezes
Knife
Ruler
Mass weigher
Test tube holder
Potato
Tile
Beaker
Variables
I will have to keep these constant to make it a fair test Same potato as it may have a different starch or water content Surface area of potato because the lager surface area the quicker it will go Mass of potato Temperature will have to be the same as different temperatures will change the speed of it and will give different results Same test tube
Same time in the solution as different time will make a bigger effect
Method
First set the apparatus as show above
• Then cut the piece of potato up to 2cm and the width of the cork borer
• Then measure the piece on the mass weigher and then record it
• Make to solution up with the salt solution and pure water
• Put the potato in the solution
• And time it for 6mins and take it out
• To take it out pour it in to a Petri dish
• Then weigh the mass of it after words the change in mass will show whether lost or gained water witch will show if concentration is high or low.
• Then repeat for all the different concentrations
• Then draw a graph and come to conclusion and evaluation
Prediction
I predict that there will b no change in the potato at about 1 as the highest change was 2 and lowest 0 so the potato will not change when there is no increase or decrease which is shown in my preliminary results