How does a burning candle show both physical and chemical changes?

7 Answers

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kdburgess | College Teacher | (Level 2) Adjunct Educator

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The physical change occurs when the heat displaces the bonds that solidify the wax. Upon cooling, the wax is able to form the bond again. The chemical changes are much more complex. The first change is that the heat (fire) consumes the oxygen and fuels the flame. This then leads to the production and emission of carbon dioxide from the flame. As a by-product of the wick burning, you will then achieve soot as another physical and chemical change. The soot is a by product of the wick (chemical) and leaves a solid product as the emit (physical).

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yamaguchityler | Student, Undergraduate | (Level 2) Assistant Educator

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When a candle burns, there is both a physical and chemical reaction.

The physical change is quite obvious and in fact, it can be seen. When the candle burns, the wax slowly melts and the candle gets smaller and smaller. This wax, as can be seen, will drip onto the candle and stick to it. When this wax forms back into a solid and stays on the candle, that is another physical change that can occur.

The chemical reaction can be a little less obvious. The first is that the heat produced by the candle consumes both the oxygen around it, as well as the fuels coming from the flame. This will then lead to carbon dioxide emissions produced by the flame, which by the way should never be inhaled. This is the chemical change that takes place in the reaction.

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portia-howe123 | Student, Grade 8 | eNotes Newbie

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the Physical changes in the candle is that the wax melts into liquid, and then freezes back into solid. The Chemical changes are that the wick/rope/string burns, soots, and smokes.

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strwbrry16 | Student, Grade 5 | (Level 1) Valedictorian

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Candle is made up of a solid block of wax with a wick embedded in it.

1) Physical Change

When candle is lit, the heat of the flame melts the solid wax to liquid wax. This signifies a physical change from solid state to liquid state. Also, as the wax melts, the size of the candle decreases. It then solidifies and takes a different shape.

2) Chemical Change

The wax acts as a fuel when we light the candle and is basically carbon. The carbon combines with oxygen to form another chemical substance, carbon dioxide and water. Also the unburnt carbon is deposited as black substance called soot. This signifies a chemical change.

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josefina14 | Student, Grade 9 | (Level 1) Salutatorian

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The physical changes in the candle is that the wax melts, then freezes back into solid state again, and the chemical changes are that the wick burns, soot, and smoke.

engrzahid686's profile pic

engrzahid686 | College Teacher | (Level 2) eNoter

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The physical change occurs when the heat displaces the bonds that solidify the wax. Upon cooling, the wax is able to form the bond again. The chemical changes are much more complex. The first change is that the heat (fire) consumes the oxygen and fuels the flame. This then leads to the production and emission of carbon dioxide from the flame. As a by-product of the wick burning, you will then achieve soot as another physical and chemical change. The soot is a by product of the wick (chemical) and leaves a solid product as the emit (physical)

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casdusel | Middle School Teacher | eNotes Newbie

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A physical change is the substance (in this instance, wax) changing states of matter (solid, liquid, gas, plasma, and Bose-Einstein condensate) A chemical change is when the substances combine to form a completely new substance.
The physical changes in the candle is that the wax melts, then freezes back into solid state again, once it is sufficiently far away from the heat. The chemical changes are that the wick burns, or heat + oxygen + wick = Carbon dioxide, soot, and smoke. If the candle was scented, the chemicals that make the candle scented would vaporize and spread about the room in gaseous form.