How the solubility of potassium chlorate (KClO3) changes as the temperature changes

Method:

* Set-up the Bunsen burner, tripod, gauze, burette etc. as shown on the diagram sheet.

* Put 2 grams of potassium chlorate into a boiling tube. Add 4 cm3 of distilled water from the burette (a burette is used to add the water because it is more accurate than a measuring cylinder).

* Place the boiling tube in a boiling water bath and allow the solid to dissolve.

* Remove the tube from the water bath when the KClO3 is dissolved. Stir the contents with a thermometer and record the temperature at which the KClO3 crystals first reappear.

* Add another 4cm3 distilled water from the burette to the boiling tube and again allow the boiling tube of KClO3 to dissolve in the boiling water bath. As before remove the boiling tube and stir the contents with the thermometer and record the temperature at which the first KClO3 crystals reappear.

* Repeat this step another three times using the same boiling tube.

* Then take another boiling tube and add 2 grams of potassium chlorate and repeat the whole experiment in the same way to obtain a second set of results.

Calculations:

Solubility (g/100g of water) = Mass of solute (g) *100

Mass of water (g)

2*100=50

4

2*100=25

8

2*100=16.67

12

2*100=12.5

16

2 *100=10 Average temp = (temp1 + temp2)

20 2

Results:

Mass of KclO3

(g)

Volume Of Water

(cm3)

Solubility

g/100cm3

Water

Temperature (oC) at which

Crystals reappear

Temperature (oC) at which

Crystals reappear

Average

Temperature (oC)

2g

4cm3

50g/100cm3

91 oC

92 oC

91.5 oC

2g

8cm3

25g/100cm3

59 oC

55 oC

57 oC

2g

2cm3

6.67g/100cm3

45 oC

42 oC

43.5 oC

2g

6cm3

2.5g/100cm3

33 oC

31 oC

32 oC

2g

20cm3

0g/100cm3

25 oC

27 oC

26 oC

Conclusion:

From performing this experiment I have found that the solubility of potassium chlorate (KClO3) increases as the temperature increases.

I also have concluded that most solids that dissolve in water behave like potassium chlorate, although the amount that dissolves will be different.

Evaluation:

After doing the experiment and concluding that the solubility of potassium chlorate increases when temperature increases and also finding that other solids behave like this I feel that the experiment was successful. By using accurate apparatus like the burette and thermometer I believe that I have obtained reliable results. By also repeating the experiment to get a second set of results and finding the average this has also made my results reliable. From the graph I can clearly see it is a solubility curve as it should be and I have drawn a line of best fit to suit my results.

There are also other experiments that could be done to obtain results for the solubility of potassium chlorate and surely the same conclusion would be drawn up. But I think that the experiment I did was accurate and reliable enough.

Obtaining evidence

Liam Brogan S1F