Design task: Solubility

What is solubility?

What is solubility? Solubility is the amount of a solid that will dissolve in 100g of water. It is measured in grams per 100g of water. 1g of water = 1cm3 of water Therefore solubility can be measured in g/100g water OR g/100cm3 of water.

What is a saturated solution?

What is a saturated solution? When no more solute will dissolve in a solvent, it is called a saturated solution. When no more solute will dissolve you will see some solute left at the bottom of the beaker or test tube.

Cooling to saturation point The saturation point is the point at which a saturated solution has just been made. To find the saturation point of a salt at a certain temperature, prepare hot solutions with different quantities of solute, and cool them until crystals start to appear.

Design Task Plan an investigation into temperature and solubility. This is a very open task as there are various ways this can be approached. You will have to devise your own research question. Check you are meeting the requirements of the assessment criteria as you are planning your investigation.

There is information about solubility on p67 of the textbook.

Factors to consider What will you vary? (Independent variable) What will you measure? (Dependent variable) What will you keep the same? (Controlled variables)

What chemicals can I use? Sugar Sodium chloride (table salt) Copper Sulphate Potassium Chloride Note: You do not need to use 100g of water to calculate solubility in g/100g. Using less water will reduce the amount of solute required (which avoids wasting chemicals) and time taken to achieve a saturated solution.

What equipment can I use? All regular laboratory equipment is available to you including: Test tubes Beakers-various sizes Spatulas Stirring rods Thermometers Electronic Balances Timers Measuring cylinders Kettle

What should I do if I get stuck? Find out about solubility and possible experiments by researching. Start with your textbook. You can ask for help and advice from your teacher. Your teacher can provide you with a help sheet but this may lower the level you can obtain. Try out your ideas to see if there are any problems with your method and make adjustments.