In Year 5, we have been putting our knowledge of properties of materials to the test. Last week, we recapped vocabulary such as: conductor, insulator, magnetism, transparency, hardness, toughness and solubility. This week, we did an experiment to test solubility by making salt solutions.
We learned about saturation points and attempted to make saturated saltwater solutions by adding salt in the same increments each time, stirring until it had dissolved and recording how much we had added as a tally. When the salt (the solute) would no longer dissolve into the water (the solvent), we knew the solution was saturated.
Then came the fun part! We tested what effect a saltwater solution had on the buoyancy of an egg and how it differed to the effect of normal water. The egg sank to the bottom of the normal water.
However, the egg floated in the saturated saltwater solution!
Some groups had an egg which only floated half way to the top and from this we deduced that their solution must not have been fully saturated.
Finally, we spoke about the Dead Sea and hypothesised that people must float in it so easily due to a high salt content.