To see how solubility of sugar dissolved in water is affected by temperature

Firstly I shall tell you about the basic facts about sugar. Sugar

• Melts easily
• Soluble in water and solutions
• Does not conduct electricity
• Is a compound

Now I shall tell you how sugar dissolves, and how we get a saturated solution.

Here is a simple diagram to help explain

Atoms/Particles in a molecule are bonded/held tightly together. This is because they gain negative electrons between them. However heat contains positive electrons, due to the fact that negative attracts positive, the negative sugar particles attract the positive nuclei, in the charged water molecules. The water molecules attack the sugar particles at a great force, which causes them to separate. The particles at the end crumble away first, and eventually so do the others, and therefore the sugar dissolves.

Basically as you heat up the water molecules, they begin to vibrate faster and faster. The water molecules gain more energy, and therefore they are able to break the sugar molecules. The sugar is now separated into individual particles. As the temperature of the water increases molecules expand, therefore there is more space between the sugar particles. Due to this more sugar will be able to dissolve.

Here is a diagram to show this –

The diagram shows that the

                                                                                             water has hydrogen bonds

                                                                                            between them. The sugar    

will dissolve because it can

                                                                                      form hydrogen bonds.                                

However there is a limit to the amount of sugar that will dissolve. This is otherwise known as saturation. Saturation is influenced, when the particles from a solid are dissolving and crystallizing in the solution at the same rate. This occurs when the solution contains as much of the dissolved substance as possible at a particular temperature. When this procedure takes place, we are able to know the saturation point, (how much of the substance has dissolved).

Prediction – I predict that the hotter the water is, the more sugar will dissolve. This is because the water molecules gain a lot of positive energy from the heat. Therefore they will attack the sugar molecules. The water molecule will gain positive nuclei and will get attracted the negative nuclei in the sugar molecules. This will force them to collide harder and faster allowing them to break.

Preliminary work – I did a preliminary test to see what the best way would be to stir the solution once the sugar had been added.

I firstly filled a beaker with cold water, and then added a spoon of caster sugar in it.

I stirred the solution in a circular motion, and soon figured that the sugar was not dissolving easily, and seemed to be positioning itself at the centre of the water.

I then stirred the water from side to side, and soon figured that this was the best way to stir the solution. The water was more turbulent, and was beginning to dissolve the sugar.

Plan – The equipment I will use is -: A Beaker

                                                           A Bunsen burner

                                                           A Tripod

                                                           A Thermometer

                                                           A Stirrer

          I will also need -: Granulated Sugar/Sucrose

                                       Water

I will set up all my equipment and place cold water into the beaker. I shall record the weight of my beaker with the water, will then place a thermometer in it. After heating the water with a Bunsen burner, I will record my result every 10 C starting at 20  C. I will continuously add sugar, half a teaspoon at a time, until the sugar no longer dissolves, and seems to be reaching its saturation point. At this point I will measure the weight of the beaker with its solution. I will minus the weight of the cold water and beaker from that of the beaker containing my solution. I will repeat this same experiment three times for each different temperature. This is to enable that I have a consistent, reliable and fair set of results. I will neutralise the thermometer each time, and make sure I use the same amount of water to begin with each time. This is also to make sure that I have an accurate test. I will keep my contents for it will be precise and reliable evidence. Finally I shall take safety precautions, this shall be done by wearing a lab coat, goggles and also gloves. It will protect me from any dangerous events, if they tend to occur.

Results – Here are the results of my experiment. They show the weight of how much sugar has dissolved in the solution. I used a scale to measure the weight and made sure that the cursor was on zero each time. I also made sure that my scales were clean, this would ensure that there were no traces left on the scales from previous experiments.

As you can see from the above table, I have decided to repeat my experiments three times, this is to ensure reliability.

From these results, I have taken all my averages for each temperature –

20. C – 3g

30. C – 3g

40. C – 4g

50. C – 5g

60. C – 7g

70. C – 9g

80. C – 11g

Conclusion – Above I have drawn two graphs. One of them contains the line of best fit, and the other contains the average amount of sugar plotted beside its temperature. As you can see my graph shows a curve. This has occurred because; as the water is heated the positive electrons get charged. As the temperature of the water increases, so does the charge. These positive charges in the water get attracted to the negative charges in the sugar. Therefore when the temperature is increased, the sugar molecules are broken at a greater force, for they have more energy. The hotter they are, the better because the force is increased. Therefore the hotter the water is, will mean that more sugar will dissolve. My prediction was correct, for my results prove that as the temperature of the water increases, so does the solubility level of sugar. Also because I said that when the water was heated, the water molecules gained a lot of positive energy from the heat. Therefore they attracted to the negative nuclei which caused them to collide harder, allowing them to break.

Evaluation – I think that the evidence that I have collected is extremely sufficient and accurate to draw a firm conclusion. I only had one set of anomalous results. This occurred when the temperature of my water was 20 C. At this temperature 2.5g of sugar dissolved two out of three times. Although I had these anomalous results, I feel that my results were very sufficient and allowed me to draw a firm conclusion. Considering the fact tht I had a lack of professional, more reliable resources I made effective use of the apparatus I had in order and performed my experiment in the best possible way that I could. The main point was that I achieved my aims, I was very fair, and I had accurate and results. If I were to redo this experiment, and make it more accurate and reliable, I would use a mechanical stirrer to ensure that each experiment was stirred at the same rate. I would also use a water bath, to keep the temperature constant. Finally I would do each experiment 5 times instead of 3. This would enable a consistent and fair set of results. If I were to extend the investigation, I would try using different types of liquids other than water. For example salt water.