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Posted by on Saturday, October 21, 2006 at 10:00am.

What happens when a candle is alight (on one side we had to show physical change and on other side the chemical change). The question sheet says 'Explained both changes using the Big Idea of Energy.'

The physical changes are what you can see, and what you can measure. Include heat.

The chemical changes: liquid wax changing to light, smoke, heat?

You need to explain these

Thankyou for your help but what is the Big Ideas of Energy"? Can you explain please?

See my response to Melody near the top of this page.

That's great, thanks.

  • science - , Monday, September 17, 2007 at 11:59am

    When a candle burns the wax melts ( a physical change). Some of the melted wax changes into gas which burns with the flame. This is a chemical change.

  • science - , Wednesday, December 5, 2007 at 11:56am

    when a physical change happens, it is visible

  • science - , Wednesday, December 5, 2007 at 12:01pm

    9yyu59yuop54i9y45yj95uuhtjv 89y yyt3y tgy54

  • science - , Sunday, February 3, 2008 at 8:41am

    im doing the same project!

  • science - , Saturday, March 22, 2008 at 10:21am

    does the rope burn too when it is lighted..

  • science - , Tuesday, March 25, 2008 at 3:13pm

    im doing this project too its a levelled assessed task and i needed help is that cheating?!!

  • science - , Sunday, April 27, 2008 at 5:26am

    a physicalchange is the wax melting and a chemical change is the hydrogen and carbon removed. im doing the same project too

  • science - , Sunday, May 4, 2008 at 3:34pm

    -Im probably not the samee 1 as yooh but im doing a h/w task on this *groans*

    -Physical'change: Thee Heat from the flame burns the wax, which melts into a liquid, running down the side of the candle.

    -Chemical'change: The wax is heated so much it turns to a liquid; which runs down the side of the candle.
    Somee of it hardens at the bottom (i.e. if the candle is on a plate, or surface of somethink), Buh some of the liquid wax turns into the gases: hydrogen and carbon - 'cause there are hydrogen &+ carbon paticles in the wax.
    These gases then burn with the flame.

    Hopee youuh findd this info helpfuul


  • science - , Tuesday, May 20, 2008 at 1:03pm


  • science - , Wednesday, June 11, 2008 at 1:46pm

    a chemical change is when you cant see it hope this was helpful

    join the club i was stuck on this homework aswell...

  • science - , Tuesday, June 17, 2008 at 2:24pm


  • science - , Friday, June 27, 2008 at 11:24am

    what are the physical changes???

  • science - , Sunday, June 29, 2008 at 6:21am

    A physical change is the wax melting and a chemical change is when it lets out heat and light energy - I think....
    The difference between a physical and a chemical change is that you can see the physical changes but but you can't really see the chemical changes. The reactants are probably hydrogen, oxygen and carbon, (I'm not too sure) and .... yeah. I hope you find this useful, Bye!

  • science - , Sunday, June 29, 2008 at 6:24am

    By the way... daos, are you from Mr Archer's chemistry class by any chance?

  • science - , Sunday, June 29, 2008 at 10:11am

    What do you mean by a chemical change is the hydrogen and carbon removed?

  • science - , Monday, July 7, 2008 at 10:25am

    hydrogen + oxygen = H2O (water)
    Oxygen + carbon = CO2 (carbon dioxide)

  • science - , Sunday, October 19, 2008 at 5:39pm

    im doing exactly the same thing.
    Chechimal change : Chemical Change: Light and Heat is produced. It will make the atoms move around with the energy. The Hydrocarbon vapours burn to give a Combustion reaction with Oxygen of the air which converts the vapour into CO2, CO, C (soot) and H2O vapour (together with Heat and Light).
    (If it's a scented candle, the fragrant substance is also vaporised and imparts a pleasant aroma to the atmosphere). The chemical change is the burning of the wax producing CO2 and H2O Chemical- The wick is burned, change the molecular makeup of the molecule.

    Physical change :
    a)...Solid wax Increases in Temperature to its Melting Point by the addition of Sensible Heat.
    b)...The Wax melts to liquid by the addition of Latent Heat.
    c)...Addition of more Sensible Heat brings the wax to its Boiling Point.
    d)...Further addition of Latent Heat vaporises the Wax to a gaseous form. The physical changes are the melting and evaporating of the wax, paraffin. Physical- shape change, some of the wax becomes liquid.


  • science - , Saturday, December 6, 2008 at 3:41am

    phyisical changes are always visable but chemicals are not

  • science - , Sunday, January 4, 2009 at 11:33am

    phisical change ( u can see it ):

    A candle melts because of the heat of the flame. The wax turns to a liquid and drips down the candle base. On the way some of the wax turns back to a solid. But most of it gets lost in the air.

    chemical change (i think i got stuck on this part as i lost the hwk sheet) :

    When a candle melts 3 gases are let off. The gasses are hydrogen, oxygen and carbon dioxide. These gasses burn with the flame.

    xx kitty xx hope it is helpful

  • gzcm dvax - , Sunday, February 1, 2009 at 1:07pm

    vqtdirol zdnmgyi fvwdx hmrlq ectudknaq ihdsolm yptsqni

  • science - , Monday, February 2, 2009 at 3:32am

    hpe its helpfulx
    i gt stuck aswellxx
    The physical change is the wax melting.
    The chemical change is the hydrogen and carbon particles (from the wax) rising into the air and mixing with carbon dioxide.Remember the carbon dioxide is already in the air! then the particles cool and drop as a odour!
    cool ar what... this answer is correct i asked my dad who is a science teacher!

  • science - , Monday, February 2, 2009 at 4:19pm

    the big idea of energy: energy can never be created or destroyed it merely changes forms.

  • science - , Sunday, April 5, 2009 at 8:32pm


  • science - , Friday, April 17, 2009 at 6:39am


  • science - , Wednesday, May 13, 2009 at 4:45pm

    The Exation below is what is needed for burning:
    methane+oxygen-carbon dioxide+water.

    hope this is helpfull, im doing the same project tooo :)

  • science - , Friday, December 4, 2009 at 11:10am

    what happens when a candle alight

  • science - , Tuesday, February 23, 2010 at 10:22am

    i have this homework too

  • science - , Wednesday, February 24, 2010 at 5:49pm

    i mm sooo dumb

  • science - , Thursday, April 29, 2010 at 1:02pm

    im doing this for ma lil sis and even i dnt knw lol fanx for everyone that has help also wen the candle is aloght it realeases both heat and light energy into the atmosphere around it

  • science - , Monday, June 21, 2010 at 10:32am

    I don't know so stop ansking mmeeeeeeeeeeeeeeeeeeeeeee !

  • science - , Saturday, September 18, 2010 at 1:28pm

    im not doin this and ur all gay

  • science - , Thursday, November 25, 2010 at 12:33pm

    when the candle is heated it melts (physical change) and when it burns it is a chemical change. candle wax is made from hydrogen and carbon.
    im doing this homework too!!!!!

  • science - , Sunday, January 2, 2011 at 12:13pm


  • science - , Tuesday, February 1, 2011 at 3:25pm

    i have exactly the same work!!

  • science - , Tuesday, February 7, 2012 at 6:28pm

    this homework is a 7th grade question im a 7th grader its easy

  • science - , Monday, November 11, 2013 at 2:28pm

    a physical change is when a surtain substances into another substance but is able to change back to the way it was E.G. ice turning into water and water into ice.
    A chemical change is when a substance changes into a completly different substance and is unable to change back to the way it was before.
    (hope this helps and by the way i am only in year 3)

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