Required Practical - Osmosis
Biology: Edexcel IGCSE, topic 2.1.19
Osmosis
Osmosis is the diffusion of water across a partially permeable membrane from a dilute solution (high concentration of water) to a concentrated solution (low concentration of water).
Investigating Osmosis
This experiment shows the effect of water concentration on osmosis.
Measure change in mass
- Cut discs of raw potato and measure their mass.
- Put discs in different concentrations of sugar or salt solution.
- After 30 minutes, measure the mass of each disc again.
Calculate percentage change in mass
- Subtract the final mass from the initial mass of each disc.
- Divide this number by the initial mass and then multiply by 100 to give a percentage change in mass.
- The concentration in which the potato's mass changed the least is closest to the water concentration of the potato (because the least water has moved into or out of the potato by osmosis).
Test yourself on Required Practical - Osmosis
What is an independent variable?
Steps Involved in Investigating Osmosis
The percentage change of mass in the osmosis experiment is worked out by which equation?