Question : Raman while doing an experiment to find out the percentage of water absorbed by raisins measured the mass of dry raisins as 50g. He soaked the raisins in water for four hours and again measured the mass as 80 g Calculate the percentage of water absorbed by the raisins. He then placed swollen raisins in concentrated salt solution for four hours. What will he observe ?

Question : Raman while doing an experiment to find out the percentage

1.	Question : Raman while doing an experiment to find out the percentage of water absorbed by raisins measured the mass of dry raisins as 50g. He soaked the raisins in water for four hours and again measured the mass as 80 g Calculate the percentage of water absorbed by the raisins. He then placed swollen raisins in concentrated salt solution for four hours. What will he observe ?
Answer» Solution :The raisins will absorb water by the process of ENDOSMOSIS. Hence the weight will increase INITIALLY. The percentage of water absorbed by the raisins is calculated as follows: Calculations : Weight of dry raisins = `=50g =W_(2)` (2) Weight of swollen raisins `=80g=W_(2)` Weight of the water absorbed by raisins = `W_(2)-W_(1)=80-50=30` Percentage (%) of water absorbed by raisins`W_(2)-W_(1)//W_(1)xx100` `=30//50xx100=60g` LATER, when these raisins are transferred to concentrated salt solution, there will be exosmosis. The raisins will throw out the water and they will reduce in their weight. Raman will thus observe the phenomena of exosmosis as the medium in which the raisins are KEPT is hypertonic. The membrane of raisins act as the semi permeable membrane in both the cases,