| time
requ.: |
10 minutes. |
|
objective: |
Everyday
chemistry with candles. |
| material: |
- knife
- 2 test tubes d=18mm
- test tube holder
|
- lighter
- burner
- powder spatula 10mm
|
| chemicals: |
|
- octadecane
- stearic acid
- stearine candle
- paraffine candle
|
|
procedure 1: |
Scrape with a
knife some wax from a paraffin and a stearin candle. Put one spatula of
wax into a test tube, add 2 ml bromothymol blue and heat for a minute. |
|
observation 1: |
Positive test
result (yellow) with the stearin candle, negative test result (blue)
with the paraffin candle. |
|
interpretation 1: |
Stearic acid
is a weak acid, paraffine is not acidic. |
|
procedure 2: |
Make a blank
test with pure stearic acid and pure octadecane. |
|
observation 2: |
Positive test
result (yellow) with the stearic acid, negative test result (blue)
with octadecane. |
|
disposal of: |
Garbage box. |
|
source: |
Barke, H.-D. et al.: One Hundred
Chemistry-Experiments to Avoid Chalk and Talk; University of Muenster,
2004. |
