Osmosis Flashcards
Osmosis
Water may move across cell membranes via osmosis.
Osmosis is
the diffusion of water from a dilute solution to a concentrated(low concentration of water molecules)
solution through a partially permeable membrane.
Osmosis practical aim and what will we do
To investigate the range of concentrations of salt or sugar solutions on the mass of plant tissue
You will:
Prepare samples of potato and place them in different concentrations of sugar or sodium chloride (salt) solution
Make measurements of mass and length of your samples before and after soaking them in solutions
Calculate the percentage change in mass of plant tissue
Plot, draw and interpret appropriate graphs
In this practical, you should take care to prepare your samples of potato carefully and record your measurements accurately
This practical can be carried out with either salt or sucrose solutions of at least five different concentrations
Step one of practical
Use a cork borer to cut 5 potato cylinder the same diameter
step 2 of practical
Use a scalpel and ruler to make them the same size(peel potato peel so it doesn’t affect osmosis
step 3 of practical
Measure mass and record in table of results
step 4
Measure 10 cm cubed of different concentrated solutions and pour into test tube make sure distilled water as tap has dissolved substances
step 5
Remove potatoes after period of time and dry them blot dry/try towel make sure no internal water gets out as this will ruin experiment and measure mass
Variables
you should measure both the mass and the length of each potato cylinder before and after it has been submerged in solution - these measurements are your dependent variables from which you will calculate the percentage change in mass and length
The independent variable is the concentration of salt or sucrose solution in mol dm3
Important control variables are type and volume of solute in solution, temperature, and time
