Q- Write four main steps of the method involved in an experiment on determining the percentage of water absorbed by raisins in the laboratory.
Answer- The four main steps of the method involved in an experiment on determining the percentage of water absorbed by raisins in the laboratory are as follows:
1. Weight some dry raisins and note down their weight before putting them in water (W1).
2. Keep the dry raisins in a petridish containing plain water for 1 to 2 hours. Raisins swell up due to the process of endosmosis.
3. After 1 to 2 hours remove those raisins from water in petridish and again weight them after getting swellen (W2).
4. Now the last step is to calculate the percentage of water absorbed by raisins after 1 to 2 hours dipped in water.
For example:
Let us assume,
W1 (Weight of raisins before placing in water) = 10 g
W2 (Weight of raisins after placing in water) = 12.5 g.
According to question,
Percentage of water absorbed by the raisins:
= (W2-W1) x 100/W1
= (12.5-10) x 100/10
= 25%
Therefore the raisins absorbed 25 percent of the water.
In this way we can calculate the percentage of water absorbed by raisins.
The two main precautions to be taken while we determine the mass percentage of water imbibed by raisins are as follows:
1. The raisins we had taken for this experiment should clean as well as dry and should have intact stalks.
2. Gently remove the extra water of the swollen raisins by placing them on a blotting paper.