Investigate the solubility of table salt (NaCl) in distilled water at different temperatures.

Procedure

1. Measure out 10ml of distilled water using a graduated cylinder and pour the water into a test tube. Repeat this 7 times so that you have 8 test tubes with 10 ml of distilled water in each.
2. Place a thermometer into your first test tube and wait to see what the real temperature of the water is and record it.
3. Using a scale, measure out portions of 0.5g of salt and dissolve them one by one in the distilled water.  If it doesn’t dissolve by itself, close the tube with a stopper and shake it.  Try not to let salt stick to the sides of the test tubes as this will influence your results. Only add the next portion in once the previous one has completely been dissolved i.e. the solution is transparent, and there is no salt residue or excess salt on the bottom of the tube.
4. At one point you will see that the last portion of salt has not been dissolved completely in the water (the salt settles down on the bottom and will not dissolve if you shake the test tube).  Record the amount of salt that been fully dissolved i.e. the amount of portions before the last one.
5. To improve your accuracy, take the amount of salt fully dissolved previously and add it all at once.  Shake the test tube with a stopper to speed the process up.
6. After all the salt has been dissolved, take portions of 0.05g and add them in to see the maximum amount of salt that can be dissolved. Make sure you are patient with the experiment, because the salt will not dissolve quickly once the solution is very saturated.  
7. Keep adding these portions of 0.05g of salt until no more can dissolve.  This will give you the maximum amount of salt dissolved in 10ml of distilled water at a certain temperature to the nearest 0.05g.
8. Repeat the previous steps 3 times using distilled water at higher temperatures.  Raise the temperature of the distilled water by placing the test tube in a beaker with water on a hotplate.  It is suggested that you use the same interval between temperatures (for example: if my initial temperature was 15˚C then my other 3 should be something like 40˚C, 65˚C, 90˚C with a difference of 25˚C)
9. Because it is difficult to prevent heat loss, as long as you use the same method every time for heating the distilled water, the results will be relevant.

Data Collection, Processing and Presentation

Conclusion

From the results it is clear that the temperature of the distilled water directly affects the solubility of table salt (NaCl) in it.  The higher I raised the temperature the more salt would fully dissolve in the test tube.  The graph also shows this direct proportionality.  

In this experiment I formed a solution with distilled water being the solvent and salt (NaCl) being the solute.  

        This relationship between temperature and solubility can be explained with the following.  Temperature is a measure of the average kinetic energy of the molecules in a substance.  Therefore, if the temperature increases the molecules move faster.  For something to dissolve in something else, energy is needed.  This energy is used to split up the particles of salt and align them up with the particles of the water as shown in diagram.  

The faster the particles are moving, the more energy they have to break up this ion, therefore more of it can dissolve.  Also, the faster they move the more chance they have of colliding with the salt particles from the right angle, therefore it will increase the solubility.