Salty Solutions & Marvellous Mixtures.... Science week continues...

Following the creation of the smoothies we decided to look a little more closely at what makes a mixture and what makes a solution. We started off by talking about what solutions and mixtures are and then did some experiments to discover a little more about how to make and separate them.

Our first experiment was to discover which substances can be made into solutions with water (Aim)

You will need (Apparatus)
8 transparent glass
50ml of tap water in each glass (to make sure it is a fair test)
Sand
Salt
Gravel
Bath salts
Sugar
Chalk
Instant Coffee
Flour
a teaspoon / stirrer

What we did (Method)

1. First pour 50ml of tap water into each of the transparent glasses.
2. Next put the sand into the first glass of water and mix well using a spoon/stirrer and watch to see if the sand dissolves.
3. Repeat for the other substances listed above.

What did we find out? (Results)
We discovered that salt, bath salts, sugar, instant coffee dissolved in water. Sand, gravel and chalk did not dissolve in the water. We thought that the flour had dissolved, but when we left it for a few
minutes it began to separate again so we learnt that it does not dissolve in water.

Once we had made these solutions and mixtures we wondered how we could separate them again. The mixtures (sand, gravel, chalk and flour) seemed easy to separate using the physical process of sieving/filtering. The solutions were a little more tricky and needed a chemical process because it required heat. This is how we did it.


How to separate the salt and the water in a saturated salt solution (Aim)


What you will need (Apparatus)
Glass container
Salt
50ml Water
Stirrer
Filter
Muslin square
Foil dish
A cold plate
Tongs and heat proof gloves
Bowl to collect the water
A heat source

What we did with the help of Mummy and Grandma (Method)
A salt solution was made by adding salt to 50ml of water until no more salt can dissolve, making it a saturated salt solution.
Filter the solution into the foil dish using a funnel and a piece of muslin to stop any undissolved salt going into the dish.
Then heat the salt solution.
When the solution starts to boil, hold the plate at an angle over the foil dish using the tongs, whilst wearing the heat proof gloves. The plate needs to be pointing down towards the water collecting bowl.
Watch as the salt begins to form crystals and water condenses onto the plate.

What happened? (Results)
The salt turned back into crystals once all the water had evaporated into water vapour. When the water vapour touched the cold plate it condensed back into water droplets and dripped into the collecting bowl. When we tasted the water it was no longer salty.

Whilst we were watching the solution separate it reminded us of the stages of the Water Cycle.
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