Experiment #1Experiment #1

Post-LabPost-Lab

Candle BurningCandle Burning Class observations for Part B and CClass observations for Part B and C Sample observations:Sample observations:

1. 1. Colors ofColors of: flame, wick, “wax”: flame, wick, “wax”2. “wax” is an interpretation!2. “wax” is an interpretation!3. other senses? (smell, touch, etc)3. other senses? (smell, touch, etc)4. Heat rises? (observation or interpretation?)4. Heat rises? (observation or interpretation?)5. Qualitative vs. Quantitative5. Qualitative vs. Quantitative

““Candle is bright”Candle is bright”““Candle is bright in a normally lit room”Candle is bright in a normally lit room”““Candle is as bright as a cmCandle is as bright as a cm22 of Fe raised to a of Fe raised to a

temperature of 700temperature of 700ooC.C.

How does a candle work?How does a candle work?-Hints:-Hints:

*Consider the shape that was “burned” into the *Consider the shape that was “burned” into the note card. note card. What does this tell you about the What does this tell you about the

wick’s wick’s role?role?

*Consider the similarities and differences *Consider the similarities and differences between the three items that hold a flame up between the three items that hold a flame up front (candle, tiki torch, bunsen burner)front (candle, tiki torch, bunsen burner)*Consider the 3 phases that are present when *Consider the 3 phases that are present when

the candle is burningthe candle is burning*What does “wick” actually mean? What does a *What does “wick” actually mean? What does a

wick do for a candle?wick do for a candle?*Why did the flame seem to “jump” in Part C #1?*Why did the flame seem to “jump” in Part C #1?*Why was the flame extinguished in Part C #8?*Why was the flame extinguished in Part C #8?

How a candle worksHow a candle works The wick is “lit” by a heat sourceThe wick is “lit” by a heat source

This begins to melt the solid paraffin wax into liquid wax.This begins to melt the solid paraffin wax into liquid wax. The wick will then “wick” or draw the liquid wax toward the flame The wick will then “wick” or draw the liquid wax toward the flame

where the reaction is taking placewhere the reaction is taking place The liquid wax becomes a gas and it is this gas that is undergoing The liquid wax becomes a gas and it is this gas that is undergoing

the combustion reaction the combustion reaction In the tiki torch, the fuel is already a liquid, and the wick draws the liquid In the tiki torch, the fuel is already a liquid, and the wick draws the liquid

toward the reaction site (flame)toward the reaction site (flame) In the Bunsen burner, the fuel is already a gas so the reaction happens In the Bunsen burner, the fuel is already a gas so the reaction happens

immediatelyimmediately The wick is actually not the fuel like many people believe… it’s The wick is actually not the fuel like many people believe… it’s

actually the wax of the candle! actually the wax of the candle! The wick is actually cooled by the vaporizing wax (like our sweat cools us)The wick is actually cooled by the vaporizing wax (like our sweat cools us) The wick becomes black and brittle because when the flame is extinguished, The wick becomes black and brittle because when the flame is extinguished,

the liquid wax that is saturating it cools and becomes a solid againthe liquid wax that is saturating it cools and becomes a solid again