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[Teh Krypt]

58g of sodium chloride are formed when 23g of sodium is heated in excess chlorine. Calculate the formula of sodium chloride

 

[Nightchill]

Atomic number of Sodium = 11
Atomic number of Chlorine = 17

58g total
Since 23g is Sodium this means 35g is Chlorine.

35/23 is roughly the same as 17/11 (i.e. molecular weight ratio)

therefore ratio is 1:1

Hence NaCl

 

[Teh Krypt]

Ty now I can do all my homework.. nerf forgeting something so simple that we did in class on friday, eh?

 

[Teh Krypt]

Prawned.. now im confused.

Water is split by electrolysis producing 0.2g H and 1.6g O

Calculate the forumla of water.

 

[DocWolfe]

this is noob crap

Mass O = 1.6g
Moles O (moles = mass/mr) = 1.6/16 = 0.1

Mass H = 0.2g
Moles H = 0.2/1 = 0.2

Ratio O:H = 1:2

Formala = H2O

 

[DocWolfe]

and Krypt if you cant do these dont take up A-Lev chemistry where you have to do back titrations and ph calculations.

 

[Teh Krypt]

Originally posted by DocWolfe
and Krypt if you cant do these dont take up A-Lev chemistry where you have to do back titrations and ph calculations.

Fyi I get high A's in my GCSE tests. But I still don't understand, why did you divide my 16 and then 1?

 

[SilverHood]

lol, who needs to do calculations to know that Water is H2O?

 

[Teh Krypt]

Originally posted by SilverHood
lol, who needs to do calculations to know that Water is H2O?

Me because thats teh question?

 

[DocWolfe]

16 is the Mr of Oxygen and 1 is the Mr of Hydrogen... the Relative Atomic Mass... if you look at the periodic table, thats where you get the values from

 

[Teh Krypt]

Like docwolf wtf is mr?

edit: posted at same time as above and silly me for not looking but I cba to lookup on the net ;p dont have my book with me.

 

[DocWolfe]

I jsut said Mr is the relative atomic mass dont they teach you this!?

 

[Teh Krypt]

Originally posted by DocWolfe
I jsut said Mr is the relative atomic mass dont they teach you this!?

Never told us Mr, yes they teach the relative atomic mass.

 

[DocWolfe]

thats the way I learnt it.

Moles = Mass / Relative Atomic Mass (Mr)

Mass relative

 

[mirieth]

Krypt, do your own homework!

I found that stuff really hard too, carbon chemistry and titrations and all that... then again, I can forget it all now! \o/