CANDLE LAB 1.3

Purpose – To investigate the reactions in a burning candle

Experiment /Conclusion–

Step #    OBSERVATION	INFERENCE
1  …bottle over the candle water goes up about 25% flame goes out before water gets there	candle uses up the oxygen part of air and the water replaces it….air is about 25% oxygen
2.  Cobalt chloride paper goes from blue to pink on the liquid deposited on the inside of beaker	Water is given off by the candle burning.
3A  … reaction with Ca(OH)2                              (limewater) Ca(OH)2 + CO2 →  CaCO3   +  H2O                                 white solid goes milky white, solid precipitate	the gas given off by the candle causes a chemical reaction with limewater and that gas must be CO2
3C  …. reaction with your breath goes milky white, solid precipitate	Your breath has a chemical in it that reacts with limewater (from Sc. 9  you know that gas must be carbon dioxide)
2  *notice the inside of the glass there is a foggy, condensation, clear liquid droplets, film, on the inside of the glass - note sometimes you get black solid condensing on the glass	It looks a lot like the candle gives off water - Whenever a candle’s wax (Hydrocarbon/Paraffin Wax) does not burn perfectly: C25H52   +  O2 →  H2O  +  CO2 + energy  if not enough oxygen then CO or C will be formed
5   Black solid/soot was deposited on the bottom of the beaker	This black solid is CARBON  from the wax (C25H52) that didn’t have enough heat to convert to CO2 ,  … because the water in the beaker removed the heat.
6   copper coil -flame inside the coil dies down - notice the blackening of the coil	(remember a fire requires fuel, oxygen and heat) the copper coil conducts or removes the heat necessary for a flame to happen
7  glass tube - flame could be lit at the end of the tube where smoke travelled	- the fuel which was gaseous wax (looked like smoke) travels up the tube and is flammable!
8  blow out , then relight smoke	- this fuel is part of the smoke after its put out
9a  “pinch” the candle goes out	-when you pinch it, you remove the oxygen
9b   puff with different speeds of air you can blow the candle out	(- your breath may not have enough oxygen in it, or too much carbon dioxide, - the fast blowing cools the reaction too)
12   observe black particles  in bowl little black particles circulate around the bowl and some even go toward the wick	- there are convection currents (hot up, cold down) around the wick - the wick pulls up wax into its fibres, capillary action “ the wick wicks” or wix
14  add a tiny amount of water with a eye-dropper -crackling, spitting, sputtering, sizzling, psssss, bzzzz, sparking. fizzing , - candle goes out	- the water heats up to a gas and gets trapped by the wax and breaks free making a popping sound - the water absorbs the heat - the water solidifies the wax blocking the fuel intake