Effect of temperature on solubilityFeatured science projectScience project video

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Complexity level:
4
Project cost ($):
10
Time required:
1 hour to prepare, 2 hours for the experiment
Material availability:
Easily found. May be purchased at a supermarket/chemist
Safety concerns:

None.

Abstract

This experiment was done to find out how temperature affects the solubility of various substances in water. The tests were done using salt, sugar and sodium bicarbonate at different temperatures.

Hypothesis

As the temperature of the water increases, the amount of substance dissolved in the water also increases. This should be true for all types of substances.

Background

Solubility

Solubility refers to the ability of a given volume of solvent to dissolve a substance. It  is normally expressed as the amount (in grams) of substance that can be dissolved in 100ml of a given solvent at room temperature (20 °C). Most substances will become more soluble when the temperature of the solution is increased.

Some  factors that affect the solubility of a substance are temperature, air pressure and the type of solvent used. The solubility of different substances will not be the same for a given solvent. For example, some substances can dissolve very easily in water whereas others may not.

Saturation is reached when the substance cannot be dissolved in the solvent anymore. The  remaining  substance can be dissolved by adding more solvent or increasing the temperature of the solvent. When the temperature of such a saturated solvent is gradually reduced, crystals  will start to form inside the solvent.
 

Scientific Terms

Solubility, dissolve, substance, solvent, saturation, crystal

Materials

The materials required for this science fair project:

-    3 beakers
-    300ml water
-    Some ice cubes
-    1 measuring cylinder
-    1 hot plate
-    1 thermometer
-    1 kg sugar
-    100 grams salt
-    100 grams sodium bicarbonate
-    1 digital weighing scale
-    1 spatula

Procedure

1.    For this experiment, the independent variable is the temperature of the solvent (water) and the type of substance used – sugar, salt and sodium bicarbonate. The dependent variable is the amount of substance dissolved in the water. This is determined by measuring the weight of the substance using the digital weighing scale. The constants (control variables) are the type of solvent (water), the amount of water used and the air pressure in the room.

2.    The 3 beakers are labeled as “sugar”, “salt” and “sodium bicarbonate”.

3.    The temperature of the water is brought to 20°C by adding some ice cubes to the water. Once the temperature of the water has stabilized, 100ml of the water is measured using the measurement cylinder and poured into each of the 3 beakers.

4.    Sugar is added, 10 mg at a time, to the beaker labeled “sugar” and it is mixed using the spatula. The sugar is continuously added until it is not able to dissolve in the water anymore. The amount of sugar that has been added is calculated and recorded in the table given below.

5.    The beaker is now placed on the hot plate and the temperature of the solution is brought to 40°C. The sugar is again added, 10mg a time, until it does not dissolve in the water anymore. The total sugar added (including the sugar previously added) is calculated and recorded in the table below.

6.    Step 5 is again repeated at 60°C, 80°C and 100°C and the results are recorded in the table below.

7.    Steps  4, 5 and 6 are again repeated using  salt and  sodium bicarbonate. However these 2 substances will be added to the water 1mg a time instead of the 10mg used for sugar. The results are recorded in the table below.

Observation

The results show that as the temperature of the water increases, the amount of sugar, salt and sodium bicarbonate dissolving in the solution is also higher.
 


Substance

Weight of substance dissolving in the water at different temperatures (gram)

20°C

40°C

60°C

80°C

100°C

Sugar

240

300

360

420

480

Salt

35

36

37

38

39

Sodium bicarbonate

10

13

16

20

24


The graph below represents the results of our science project experiment.


Solubillity and solutions science fair project

Conclusion

The hypothesis that as the temperature of the water increases, the amount of substance dissolved in the water also increases is proven to be true.

Solubility of a substance in a solvent can be increased or reduced by  adding   another   substance. For example, adding salt in a solution saturated with sugar will enable more sugar to be dissolved in the solution. This technique is used in candy making. .

Also consider

Try to repeat the experiment by using other substances like calcium chloride, potassium permanganate or iron sulfate.

The experiment can also be repeated using different solvents like alcohol or benzene.

References

Effect of temperature on solubility - http://preparatorychemistry.com/Bishop_solubility_temperature.htm

Solubility of substances in solution - http://chestofbooks.com/food/science/Experimental-Cookery/Solubility-Of-Substances-In-Solution.html

Solubility in water - http://www.lenntech.com/air-purification/gas-purification-techniques/solubility-in-water.htm

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