A chip off the old block
Problem: Mr. Haddock the fish shop owner has a problem. He has cut a large number of potatoes into chips to cook the next day but his fridge has broken down and he needs to keep the chips fresh and firm until the next day, until he can use them.
Solution: Mr. Haddock must keep the chips in an environment that is such that it will inhibit osmosis and stop the chips from increasing or decreasing in mass. As osmosis is the movement of water molecules across a partially permeable membrane from a region of high concentration to a region of lower concentration he must place the potatoes into an environment in which the water concentration is the same in the inside of the potato cells and in the environment they are in, in other words he must find an equilibrium. To create this equilibrium, or isotonic solution to put the potato chips into he must make sure that there are the same number of dissolved particles in the water environment as there are in the potato itself. These dissolved particles may be, for convenient use of household materials either salt (sodium chloride) or sugar. The idea is to dissolve the correct amounts of either sugar or salt particles into the water the potatoes will go into so as there will be no greater concentration of water on either side of the partially permeable membrane and therefore there will be no osmosis and no net movement and hence no water gain and no water loss.
Problem: Mr. Haddock the fish shop owner has a problem. He has cut a large number of potatoes into chips to cook the next day but his fridge has broken down and he needs to keep the chips fresh and firm until the next day, until he can use them.
Solution: Mr. Haddock must keep the chips in an environment that is such that it will inhibit osmosis and stop the chips from increasing or decreasing in mass. As osmosis is the movement of water molecules across a partially permeable membrane from a region of high concentration to a region of lower concentration he must place the potatoes into an environment in which the water concentration is the same in the inside of the potato cells and in the environment they are in, in other words he must find an equilibrium. To create this equilibrium, or isotonic solution to put the potato chips into he must make sure that there are the same number of dissolved particles in the water environment as there are in the potato itself. These dissolved particles may be, for convenient use of household materials either salt (sodium chloride) or sugar. The idea is to dissolve the correct amounts of either sugar or salt particles into the water the potatoes will go into so as there will be no greater concentration of water on either side of the partially permeable membrane and therefore there will be no osmosis and no net movement and hence no water gain and no water loss.
