Chemistry AS help please!!!!! SOS!!!! (Moles) Watch

shohaib712
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Can someonee please explain moles and amount of substance also avagadros constant (isnt it called avagadros number?)

How does it link to c12 and does it link to relative atomic mass?

Please explain it as easy as possible - im sooo confused
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JackLeggett
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Well I have Just done my GCSE's and can help with moles so hopfully this is what you want to know

So a Mole is equal to an elements Ar in Grams Eg iron has an Ar of 56 so one mole of iron weighs 56 grams.

Also One mole of gas occupies 24dm^3 which is 24000cm^3 at room temperature and pressure. So this formula triangle is handy to know for some questions. Volume/molesx24 .

Basically the mole is given to the umber 6.023 x 10^23. The reason you get this number is because thats the number of C-12 atoms you need to get exactly 12g of carbon. So if you get that number of atoms or molecules of any element or compound and it weighs the same as the elements Ar in grams. So you can use moles as a unit of measurement when talking about a substance.

Hope this helps as I am am starting AS this year, just done GCSE, it may not be detailed enough
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shohaib712
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(Original post by JackLeggett)
Well I have Just done my GCSE's and can help with moles so hopfully this is what you want to know

So a Mole is equal to an elements Ar in Grams Eg iron has an Ar of 56 so one mole of iron weighs 56 grams.

Also One mole of gas occupies 24dm^3 which is 24000cm^3 at room temperature and pressure. So this formula triangle is handy to know for some questions. Volume/molesx24 .

Basically the mole is given to the umber 6.023 x 10^23. The reason you get this number is because thats the number of C-12 atoms you need to get exactly 12g of carbon. So if you get that number of atoms or molecules of any element or compound and it weighs the same as the elements Ar in grams. So you can use moles as a unit of measurement when talking about a substance.

Hope this helps as I am am starting AS this year, just done GCSE, it may not be detailed enough
So basically moles is just a specific number which is the number of c12 atoms reuqired to convert Ar of c12 (12u) - which in kg would be very tiny into a whole number in grams?

So how would this apply to other elements?
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JackLeggett
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(Original post by shohaib712)
So basically moles is just a specific number which is the number of c12 atoms reuqired to convert Ar of c12 (12u) - which in kg would be very tiny into a whole number in grams?

So how would this apply to other elements?

So the mole is a number. And this number is the number of C-12 you would need to get 12g of carbon. Yeah so if you had Iron which has an Ar of 56 this weighs 56grams. so one mole of iron is 56
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shohaib712
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So it's used to find out how much atoms are in a specific amount of substance?

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marcobruni98
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1 mole of carbon-12 atoms have a mass of exactly 12g

1 mole of atomic hydrogen (H-1) has a mass of almost exactly 1g
(It's not exactly because protons and neutrons have slightly different mass I believe)

Thereby the Ar can be thought of as the mass in grams of one mole of an element in the periodic table. And the Mr can be thought of as the mass in grams of 1 mole of any molecule
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marcobruni98
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(Original post by shohaib712)
So it's used to find out how much atoms are in a specific amount of substance?

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Not necessarily atoms, it can be used for pretty much any particle you can encounter in chemistry. there's a nice formula:
6.022x10^23 * number of particles in Moles = number of particles

Gases are a different matter(hehe), but for GCSE you had to remember that 1 mole of any (ideal/theoretical) gas particle occupy a volume of 24dm^3 under standard conditions. In A-level chemistry and physics you will go into a lot more depth on this topic and will get plenty of practice on this.
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