Osmosis
- Created by: GreenGooSnake
- Created on: 25-05-19 21:46
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- Osmosis
- Osmosis is the movement of water molecules across a partially permeable membrane from an area of higher water concentration to a region of lower water concentration.
- Partially permeable is just one with very small holes in it. So only tiny molecules like water can pass through and bigger molecules e.g. sucrose can't.
- The water molecules pass both ways during osmosis because they move about randomly all the time.
- Because there are more water molecules on one side then the other there's a steady net flow.
- Osmosis is a type of diffusion.
- Osmosis
- Osmosis is the movement of water molecules across a partially permeable membrane from an area of higher water concentration to a region of lower water concentration.
- Partially permeable is just one with very small holes in it. So only tiny molecules like water can pass through and bigger molecules e.g. sucrose can't.
- The water molecules pass both ways during osmosis because they move about randomly all the time.
- Because there are more water molecules on one side then the other there's a steady net flow.
- Osmosis is a type of diffusion.
- The water molecules pass both ways during osmosis because they move about randomly all the time.
- Partially permeable is just one with very small holes in it. So only tiny molecules like water can pass through and bigger molecules e.g. sucrose can't.
- Investigating osmosis using potatoes
- Dilute solution
- Lots of solvent and not much solute
- Concentrated solution
- Lots of solute and not much solvent
- Hypertonic: more sugar then cell so less free water moleculesHypotonic: has less sugar then the cell so more free molecules. Isotonic: Same sugar as in the cell so same number of free water molecules then the cell.
- Cut up potato into identical cylinders, get beakers with different sugar solutions in them. One should be pure and one concentrated.
- Measure mass then leave in beaker
- Take them out and dry and measure again
- If they've drawn in water they'll have increased in mass, if drawn out they'll have decreased in mass. Calculate percentage change and plot graph.
- Percentage change = Final value - original value/original value x 100.
- Dependent variable - chip massIndependent variable - concentration of sugar solution.Control variables - Volume of solution, temperature, time, type of sugar used must be kept the same or won't be a fair test.
- Errors - may occur carrying out method, if some potato wasn't dried the excess water would give a higher mass or if water evaporated from the beakers the concentration of the sugar solutions would change. You can deduce the effect by repeating and calculating a mean percentage change.
- If they've drawn in water they'll have increased in mass, if drawn out they'll have decreased in mass. Calculate percentage change and plot graph.
- Take them out and dry and measure again
- Dilute solution
- Osmosis is the movement of water molecules across a partially permeable membrane from an area of higher water concentration to a region of lower water concentration.
- Osmosis
- The water molecules pass both ways during osmosis because they move about randomly all the time.
- Partially permeable is just one with very small holes in it. So only tiny molecules like water can pass through and bigger molecules e.g. sucrose can't.
- Investigating osmosis using potatoes
- Dilute solution
- Lots of solvent and not much solute
- Concentrated solution
- Lots of solute and not much solvent
- Hypertonic: more sugar then cell so less free water moleculesHypotonic: has less sugar then the cell so more free molecules. Isotonic: Same sugar as in the cell so same number of free water molecules then the cell.
- Cut up potato into identical cylinders, get beakers with different sugar solutions in them. One should be pure and one concentrated.
- Measure mass then leave in beaker
- Take them out and dry and measure again
- If they've drawn in water they'll have increased in mass, if drawn out they'll have decreased in mass. Calculate percentage change and plot graph.
- Percentage change = Final value - original value/original value x 100.
- Dependent variable - chip massIndependent variable - concentration of sugar solution.Control variables - Volume of solution, temperature, time, type of sugar used must be kept the same or won't be a fair test.
- Errors - may occur carrying out method, if some potato wasn't dried the excess water would give a higher mass or if water evaporated from the beakers the concentration of the sugar solutions would change. You can deduce the effect by repeating and calculating a mean percentage change.
- If they've drawn in water they'll have increased in mass, if drawn out they'll have decreased in mass. Calculate percentage change and plot graph.
- Take them out and dry and measure again
- Dilute solution
- Osmosis is the movement of water molecules across a partially permeable membrane from an area of higher water concentration to a region of lower water concentration.
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