Week 3-What happens when we mix solids with liquids?
This week we are investigating dissolving. Some solid substances dissolve when you mix them in a liquid. When a substance dissolves, it looks like it disappears. In fact it has just mixed with the liquid to make a transparent or translucent liquid called a solution. This process is reversible, which means that we can get the solid back again by evaporating the liquid in the solution. This leaves the solid behind.
The liquid a solid dissolves in is called the solvent. The most common solvent is water.
The solid which dissolves is called the solute. You will be familiar with solutes like salt and sugar.
When you mix sugar with water, the sugar dissolves to make a transparent solution. Salt dissolves in water too.
Task 1: Please try one of these experiments...either test as many of the solids in the power point as possible (or any that you have at home in the kitchen) to discover which ones are soluble and insoluble and fill in the carroll diagram or test the effect different temperatures of water have on how quickly a single solid like salt or sugar dissolves. In your books or on paper record your results as shown in the power point and explain what you have found out. Please send your work to me on Teams. Thank you.
Task 1 alternative: If you are unable to do any practical work please research dissolving to find out if these statements are true or false. Please send your work in to me in the science channel of Teams.
What affects the speed at which a solute dissolves at?
Heat can help some substances dissolve faster in water. Salt, for example, will dissolve quicker in hot water than in cold water. Stirring also increases the speed that a solute dissolves at, and sometimes so does the size of the particles of a solute. Smaller particles dissolve quicker than larger ones because they have a larger surface area to volume ratio ( the area in contact with the water is larger compared to each particle's volume).
- Substances that dissolve in a liquid are called soluble substances.
- Substances that do not dissolve in liquids are called insoluble substances.
When you mix sand or flour with water, they do not dissolve.
Dissolving is a reversible change. This means that we can separate the solvent (solid) from the solute (liquid) once it has been dissolved. To do this we can evaporate the solute by heating it. This leaves behind the solid. It may look slightly different but it is the same chemical.
Task 2: Please watch these videos which show how minerals are dissolved from rocks in the mineral water we drink and how they can be separated from it. Also how we get salt from sea water and rocks.
Extension activities: Sometimes a solid will not dissolve in water but it will dissolve in a different solvent. Visit these websites to find out more about solutes and solvent
www.bbc.co.uk/education/clips/zx7w2hv
Click on the link to go to a website with activities about dissolving.
www.bbc.co.uk/bitesize/topics/zjty4wx/articles/zpbdpbk