Substance chilique (document en anglais)

Introduction:

A chemical change occurs in a process when one or more new substances

appear and is different from the original ones formed. Here we study a common type of

reaction, which is the burning of a substance, here a candle. Energy, some oxygen gas and a

combustible material (the candle) provide the means for this type of chemical reaction. The

objectives are to describe the physical properties and change of a candle after combustion, to

take the appropriate measurement with the good amount of significant number. Then we have

to describe the chemical change during the burning of the candle according with our

observations.

Therefore, after this experience we could note the physical and chemical changes during the

combustion of the candle.

Materials:

During the experience this material are required:

- Candle with a mass of : 9.93g

- Balance

- Ice

- Metal wire screen 2x8 cm

- Beaker

- Ca(OH)2 solution

Procedure:

To begin the experiment, we obtain a candle and we analyze it. We have to light the candle

and be able to burn for 10 minutes intervals taking the mass of the candle after each 10

minutes. We have to cover the candle with a beaker and make observations. The second

experience consists to put ice on a watch glass and make some observations. The third

experience consists to put a metal wire screen on a solution of Ca(OH)2. Then all the

information about the mass of the candle is summarize on a graph.

...