Temperature & Solubility D. Crowley, 2007
Temperature & Solubility Sunday, December 02, 2018 Temperature & Solubility To know how temperature affects solubility
Word-search Have a go at the particle word-search See how many words you can find in the next five minutes…
Particles Word-search http://www.teachers-direct.co.uk/resources/wordsearches/preview.aspx?puzzle-number=7670
Solubility Are insoluble substance always insoluble?! Some substances which are insoluble in one solvent, may be soluble in a different solvent E.g. salt does not dissolve in petrol, but in water it will!
Solubility Some substances are more soluble than others Very soluble substances have a high solubility Why is it a good idea to wash dishes in hot, rather than cold water (think about temperature and solubility) The solubility of most substances increases as the temperature does This means most substances become more soluble in hot water, rather than cold water, meaning it becomes easier to wash our dishes!
Experiment You are going to investigate how heat affects the solubility of salt in water What would be a good way to investigate this? What will be your independent variable (one changed)? What will be your dependent variable (one changed by exp.)? What will you need to control? What equipment will you need? What do you predict?
Experiment We could add a known amount of salt to a beaker of water, and record how long it took to dissolve We could then repeat this, to different beakers of water, at different temperatures This would show us how temperature affects solubility Independent variable: temperature Dependent variable: time taken for salt to dissolve Control: water type; amount of salt; time of experiment etc…
Results Design a results table… These are usually the things you have measured This is usually the thing you change Use a pencil and ruler Always include your units (e.g. cm, sec, N etc…)
Mass of salt which dissolved (grams) Results Temperature of water (C) Mass of salt which dissolved (grams) 1 2 3 Average 20C 30C 60C Remember: everything else except the temperature of water is kept constant
Graph You now need to graph the class results on the board Remember, the variable you changed goes on the bottom (temperature) and the variable which was changed by the experiment goes up the side (mass of salt added) You will need to draw a line graph You will need a title, labels, line of best fit and explanation as to what your results show
Graph
We could predict that 7.5g of salt would dissolve in water at 100°C Graph Data How could you use the graph below to predict how much salt would dissolve at 100oC? We could predict that 7.5g of salt would dissolve in water at 100°C