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what happens when a candle is alight?

Hi, I'm a yr8 person in ks3 and this is my hw: What happens when a candle is alight? I have to answer these q's.

Identified a physical change that occurs when the candle is burnt
Identified a chemical change that occurs when the candle is burnt
Described one difference between a physical and a chemical change
Named the reactants and the products of the chemical reaction
Correctly written a simple word equation for the chemical reaction

I have to hand this piece of work in by Thursday 3rd of July.
I've also got this on the sheet to help me.

Wax contains hydrogen and carbon particles.

I've done some of it and I think I've done it right,

A physical change: the wax starts to melt
A chemical change: light and heat energy is produced
The difference between chemical and physical changes are that you can measure and see physical changes whereas you can't for a chemical change.
For the reactants, is it
hydrogen + oxygen equals water
carbon + oxygen equals carbondioxide
???
Thanks!
Bye!:tux:
duckwithnoname
Hi, I'm a yr8 person in ks3 and this is my hw: What happens when a candle is alight? I have to answer these q's.

Identified a physical change that occurs when the candle is burnt
Identified a chemical change that occurs when the candle is burnt
Described one difference between a physical and a chemical change
Named the reactants and the products of the chemical reaction
Correctly written a simple word equation for the chemical reaction

I have to hand this piece of work in by Thursday 3rd of July.
I've also got this on the sheet to help me.

Wax contains hydrogen and carbon particles.

I've done some of it and I think I've done it right,

A physical change: the wax starts to melt
A chemical change: light and heat energy is produced
The difference between chemical and physical changes are that you can measure and see physical changes whereas you can't for a chemical change.
For the reactants, is it
hydrogen + oxygen equals water
carbon + oxygen equals carbondioxide
???
Thanks!
Bye!:tux:


you're right about the wax starts to melt - physical change
the chemical change is that the wax is being burn't (combusted) SO light and heat energy is produced
its easy to reverse a physical change, much harder to reverse a chemical change - you can definatly measure chemical changes :smile:
you've got the starting materials right the wax contains both hydrogen and carbon (called hydrocarbons) and the products CO2 and H2O are fine :smile:
EierVonSatan
you're right about the wax starts to melt - physical change
the chemical change is that the wax is being burn't (combusted) SO light and heat energy is produced
its easy to reverse a physical change, much harder to reverse a chemical change - you can definatly measure chemical changes :smile:
you've got the starting materials right the wax contains both hydrogen and carbon (called hydrocarbons) and the products CO2 and H2O are fine :smile:


Thanks! I've already handed in my hw but I understand more about chemical changes now! Thanks!
Bye!:smile:
Hi i wanted to know what you did in your homewirk as i think i have exactly the same!:smile: its so hard :mad: but hopefully with ur help it will be easy :wink: plz plz help! :confused: :eek: :colone: :tongue::bl::bubbles::ta::tee::thumbsup::teeth::titan::reel::reaper::crossedf::worm2::yeah::ymca::yes::yeah::yy::yay::xmas::worm::work::woo::wizard::withstupid::wink2::whip::wavingtheflag::virtual_bar::stomp::stupido2::stupido:
anyone who actually has some ideas?
Congratulations on bumping a two and half year old thread.

What is your question?
Reply 6
Avatar for channy
channy
10
It burns.
Original post by hw help please
anyone who actually has some ideas?


If you have the same question...why don't you use the answer that the last person got?
Original post by hw help please

Original post by hw help please
anyone who actually has some ideas?


XD Wow! I made this thread when I was in year 8- I'm in year 11 now! XD

OK, I managed to find my book, and in my homework, I'd drawn some diagrams too, so I'm afraid that I can't help you with those, but this is what I'd put:

1. The candle has been lit.
2. The first row of particles get heated and vibrate a lot. (The solid has turned into a liquid).
3. The particles vibrate more and bump collide into the other particles. When this happens, heat energy transfers from one particle to the other.
4. The particles break away from having a fixed arrangement to being a liquid.

When the candle is alight, a chemical change/ reaction is occuring.
The carbon particles in the candle react with the oxygen in the air to make carbon dioxide.
C + O2 --> CO2
Carbon + Oxygen --> Carbon dioxide

The hydrogen particles react with the oxygen.
H2 + O --> H2O
Hydrogen + Oxygen --> Water

(By the way, the 2's are meant to be small). :]

Reactants: Oxygen, carbon, hydrogen.
Products: Water and carbon dioxide.

A chemical change is when a substance's particles rearrange to turn into a new substance.
A physical change is when something changes state.

I hope this helps! ^_^
:smile:] Thanks! even though ive already handed my homework in... but thanks anyways! :wink:
Okay listen up! I am a year 7 and yesterday we were given this task as a test my teacher wants us all to get level 6! The thing is we are ment to complete it tomorrow! Tonight is our revision night and I would love to get a E4 grade and level 6! I seriously need answers to this question. Please explain them in a way you would explain words to a year 7 nothing to tricky to understand! May be top set but yeah.........................:colondollar:
Original post by wanttolearnitall
Okay listen up! I am a year 7 and yesterday we were given this task as a test my teacher wants us all to get level 6! The thing is we are ment to complete it tomorrow! Tonight is our revision night and I would love to get a E4 grade and level 6! I seriously need answers to this question. Please explain them in a way you would explain words to a year 7 nothing to tricky to understand! May be top set but yeah.........................:colondollar:


Use the answers that were posted in this thread years ago? There isn't really much more that can be added for KS3 level :confused:

I've taught at year 7 level and you don't need to know the actual chemical reactions taking place, only that there is one.
(edited 11 years ago)

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