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Moles

when 0.1 mole of atoms of an element react with chlorine there is an increase in mass of 7.1 g. The chloride has a high melting point.
The chloride could be

A Carbon
B Magnesium
C Sodium
D Silicon
E sulfur


Why is it B - Magnesium?
Original post by jsmith6131
when 0.1 mole of atoms of an element react with chlorine there is an increase in mass of 7.1 g. The chloride has a high melting point.
The chloride could be

A Carbon
B Magnesium
C Sodium
D Silicon
E sulfur


Why is it B - Magnesium?


because magnesium reacts 1:2 with chlorine for form MgCl2. If you had 0.1 mol of Mg, you must then react with 0.2 mol chlorine. Since chlorine has mr of 35.5, 0.2 mol will be 7.1g
but I thought the mass increase means mass of the chloride in total???
Original post by jsmith6131
but I thought the mass increase means mass of the chloride in total???


no, they mean how much the mass of your original 0.1 moles increases by. You still have your original 0.1 moles, but now it's reacted with 0.2 moles chlorine, its mass has increased by 7.1g

ok?
oh, so
atom = x
atom + chlorine = x + 7.1

mole x = 0.1

mass/mole = 7.1/0.1 = 71
as we are working with chlorine, 71/35.5 = 2

so
x:Cl
1:2

Only magnesium follows this

???
Original post by jsmith6131
oh, so
atom = x
atom + chlorine = x + 7.1

mole x = 0.1

mass/mole = 7.1/0.1 = 71
as we are working with chlorine, 71/35.5 = 2

so
x:Cl
1:2

Only magnesium follows this

???


yes, because your other atoms react with chlorine in different ratios
Original post by jsmith6131
when 0.1 mole of atoms of an element react with chlorine there is an increase in mass of 7.1 g. The chloride has a high melting point.
The chloride could be

A Carbon
B Magnesium
C Sodium
D Silicon
E sulfur


Why is it B - Magnesium?


dude! i know you posted this q long time back but it came in the edexcel JANURAY 2014 paper.. can you tell me which book you got the question from?

thanks..
Original post by Paras Agarwal
dude! i know you posted this q long time back but it came in the edexcel JANURAY 2014 paper.. can you tell me which book you got the question from?

thanks..


sorry..i cannot remember...getting old!!!
Original post by jsmith6131
sorry..i cannot remember...getting old!!!


didnt know people were so unhelpful on TSR :redface:
Original post by Paras Agarwal
didnt know people were so unhelpful on TSR :redface:


I apologise but I have left school and no longer have access to any of the resources I had...it could have come from a teachers pack, it could have come from a textbook..it could have come from anywhere!!...I honsetly have no idea...
Reply 10
Original post by Paras Agarwal
didnt know people were so unhelpful on TSR :redface:


Didn't know having problems with memory is considered unhelpful these days. What is this world coming to.
Original post by Borek
Didn't know having problems with memory is considered unhelpful these days. What is this world coming to.


Lol..since when were you even part of this convo? wow ..these days schools dont teach kids its wrong to poke their nose into other people's convos
Original post by Paras Agarwal
dude! i know you posted this q long time back but it came in the edexcel JANURAY 2014 paper.. can you tell me which book you got the question from?

thanks..


Dude this question came up in my general physical and organic chemistry textbook. I use it, but I do a different board to you.
Original post by iPixelBlue
Dude this question came up in my general physical and organic chemistry textbook. I use it, but I do a different board to you.


haha okay i was just getting curious because this guy posted up the q in 2011 and it came up in the edexcel january 2014 unit 1 paper.. so i thought edexcel use some special book where they get their questions from :tongue:

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