To determine the mass percentage of water imbibed by raisins. - Class 9th Science Lab Work
Experiment - 7
Aim
To determine the mass percentage of water absorbed by raisins.Theory
Dry raisins when soaked in water they absorb water and increases their size by the process of osmosis and swell up. Osmosis is the movement of solvent from higher concentration to lower concentration through semi-permeable membrane. The difference in mass between the swollen and dry raisins gives the amount of water absorbed by the raisins.
Materials Required
Raisins, Electronic balance, Blotting Paper, Bowl, Petridish and Forceps
Procedure
Step 1: 10 dry raisins is taken and weigh them on electronic balance. Let it be x.
Step 2: These raisins were put in bowl containing water for 2 hours.
Step 3: These raisins were taken out using forceps and dried gently with the help of blotting paper.
Step 4: Weigh these soaked raisins on electronic balance. Let it be y.
Observation
The weight of dry raisins is x grams and weigh of soaked raisins is y.
Calculation
Weight of water absorbed by raisins = (y - x)
Percentage of water absorbed by raisins = {(y - x)/x} × 100
Result
The weight of the raisins soaked in water is more than the dried raisins because raisins absorbed water by the process of endosmosis.
Precaution
1. Raisins should be dried and weigh accurately.
2. Raisins should be properly soaked.
3. Excess water should be dried gently before weighing.
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