Osmosis required practical Flashcards
1
Q
Method for potato osmosis experiment
A
- Cut out identical cylinders of potato using a ruler and measure the mass of each.
- Put one into a beaker of pure water and the other into a beaker of 1 mol?dm3 sugar solution.
- put some potatoes in a beakers with 0.2M conc
- Leave the potato cylinders in the in each beaker for around 24 hours. Take them out after 24 hours and dry them with a paper towel; then measure the new mass of each.
- If the mass has increased, water has been drawn in via osmosis. If the mass has decreased, water has been drawn out via osmosis.
2
Q
Why calculate the mass?
A
- To better compare the effect of sugar concentration of the cylinders that didn’t have the same initial mass. (Increase in mass = positive percentage change, decrease in mass = negative percentage change)
3
Q
Dependant, indépendant and control variables
A
Dependent - Potato mass
Independent - Concentration of the sugar solution
Control - Volume of solution, temperature, time, type of sugar used, species of potato
4
Q
Cause of error and how to reduce effect of errors
A
- Some of the potato cylinders not being fully dried (excess water would increase the mass)
- Water evaporating from the beakers (the concentrations of the sugar solutions would change
These errors can be avoided by repeating the experiment and calculating a mean percentage at each concentration
