Do Paper Contracts When Burnt?

[ajayraho]

I have observed many times, that when a newspaper is burnt, its writings become smaller.

Do the paper really contract when burnt?

 

[SteamKing]

I have observed many times, that when a newspaper is burnt, its writings become smaller.

Do the paper really contract when burnt?

It's not clear what you are describing.

When I burn a newspaper, it turns to ash.

 

[256bits]

Hello Ajayraho,
I think your observation has credence.
The paper would have to get smaller and smaller as it burns.

For one thing all the water in the paper is driven off by the heat. The percentage change in volume night not be all that much, depending upon the makeup of the paper.
Next the carbon compounds are turned into gases that can burn with the oxygen in the air. So the paper itself is actually losing mass.

If you don't disturb the ash remaining, you can still sometimes read the now smaller print, at least where it hasn't curled up on itself.

 

[frank 971019]

the paper itself actually loosing massmoreove moreover there were water before in the paper and vaporized after burnt the peper. However paper are not pure elements so the VDW between particle actually maintain constant but number of particle decrease so the paper contracts.

 

[ajayraho]

Hello Ajayraho,
I think your observation has credence.
The paper would have to get smaller and smaller as it burns.

For one thing all the water in the paper is driven off by the heat. The percentage change in volume night not be all that much, depending upon the makeup of the paper.
Next the carbon compounds are turned into gases that can burn with the oxygen in the air. So the paper itself is actually losing mass.

If you don't disturb the ash remaining, you can still sometimes read the now smaller print, at least where it hasn't curled up on itself.

A very satisfying answer..
So what's the reason behind the yellowing of papers, when kept for a long period of time?

 

[frank 971019]

Hi Ajayraho
actually, paper are not white from the origanls. it is yellow, we use some chemical bleacher to bleach the paper, however, the chemical will left ln the paper and during a long time, the chemical on the paper will reacts with paper which give a yellow colour on the paper