Required Practical 3: Osmosis

Question 1

Name of method where the student uses a concentrated sucrose solution and distilled water to produce sucrose solutions with different concentrations

Answer 1

Dilution series

Question 2

When producing a dilution series, what formula is used to calculate the missing volumes and concentrations of the stock solution/ solutions with different concentrations

Answer 2

C1V1= C2V2

Question 3

A…solution contains has a 100% concentration

Answer 3

Stock

Question 4

Name for graph used to determine unknown water potential in a potato tissue

Answer 4

Calibration curve
(Never say plot a graph, always say plot a calibration curve)

Question 5

Why is teh percentage change in mass used instead of the actual change in mass

Answer 5

Not all potato chips start at the same mass so it allow you to compare the change in mass over different concentrations

Question 6

How can you ensure that temperature isn’t a variable that effects the rate of osmosis in/ out of teh potato tissue

Answer 6

Place the sucrose solutions into a hot water bath at 25 degrees celcius for 20 minutes to allow them to equilibraste to the same temperature (use a thermometer to check they’ve reached the correct temperature then add the potato chips and start the investigation)

Question 7

To calculate the change in mass of the potato cylinders you do…mass-….mass

Answer 7

Final
Initial

E.g if the initial mass is 3.82g and the final mass is 3.32g you do 3.32-3.82 which equals -5.0 (the change in mass is negative as the potato cylinders has lost mass)

If the potato cylinder has lost mass the change should be a negative value
If the potato cylinder has gained mass the change should be a positive value