Clay water and salt water
Two mixtures, made the same way from the same volume of water. One of them turns out to be even throughout and the other does not.
Activity 3.1.3 — clay in water
Take about 500 ml of water in a beaker. Add about 10 g of clay soil, stir well and leave it still for about a minute. Filter the muddy water into another beaker through a piece of cloth. Leave it still for about an hour, then look at whether the muddiness is spread evenly through the liquid, and whether it is as clear at the top as it is at the bottom.
Figure to be added
Activity 3.1.4 — salt in water
Take about 250 ml of water in a beaker. Add about 10 g of clean salt, stir well until it dissolves and filter through a piece of cloth. Leave it still for about an hour and check whether the clarity is the same from top to bottom. Then do to this solution what you did in activity 3.1.3.
Figure to be added
What the two look like after an hour
Clay in water
- The colour, and how see-through it is, change from place to place
- The number of clay particles in a unit volume changes from place to place
Salt in water
- How see-through it is stays the same throughout the solution
- The number of salt particles in a unit volume is the same everywhere
The test that settles it
Take a piece of metal plate with a shiny surface. Using a pipette or a glass rod, take liquid from two places in the solution, A and B, put one equal drop from each on the plate, and evaporate them. If more residue is left by the drop from one place than by the drop from the other, the mixture was not the same throughout.
Clay water and salt water are both mixtures of a solid and water, and they are not the same kind of mixture. The difference is whether the composition is the same everywhere in it.