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Edexcel Chemistry Unit 1 15th May

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Reply 220

arnab

Original post by ummm

any chance of you explaining this questio0n?

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Reply 221

arnab

if anyone can provide an explanation for the answer to these 2question for me, i will be eternally great full!!!

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Reply 222

neom

Original post by arnab

any chance of you explaining this questio0n?

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Mass = moles x RAM

Then you divide that by 1000 - coz the original was in Kg and the answer needs to be in g.

And then times by a million to get the parts per million.

Reply 223

arnab

Original post by neom

Mass = moles x RAM

Then you divide that by 1000 - coz the original was in Kg and the answer needs to be in g.

And then times by a million to get the parts per million.

]

Thank you soo much!
any chance of answering my other question?

Reply 224

neom

Original post by arnab

if anyone can provide an explanation for the answer to these 2question for me, i will be eternally great full!!!

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I'm not sure about the first one,
but you first find the number of moles

Moles = 17.1 / 342 = 0.05mol

then times that by the avagrodo's constant
0.05 x 6 x 10^23 = 3x10^23

Because there's 3 of the sulphate ions, you times that number by 3 which would give you the answer

Reply 225

mrperfect

How do you know which compound is the most exothermic? It came in the january 2012 paper

Reply 226

neom

Original post by mrperfect

How do you know which compound is the most exothermic? It came in the january 2012 paper

It has the minus sign number is bigger? lol

Are you talking about the lattice energies and stuff?

Reply 227

zulfarhan92

can any one explain the answer to the January 2010 paper question 2 (objective)?
thank you
aldbezzz peeps~

Reply 228

ShmangoBaby

Original post by zulfarhan92

can any one explain the answer to the January 2010 paper question 2 (objective)?
thank you
aldbezzz peeps~

Yeah i had a little confusion with that too but obviously as you can see when you add the two isotopes you get the answer ie; the mass that will occur in the spectrometer.

Calculation - 35+37= 72

As far as theory is concerned , i really have no idea :\ maybe you should go through the book or something. :smile:

Reply 229

sabre2th1

What time is this exam? My timetable just says PM, it doesn't state an actual time..

Thanks

Reply 230

d_94

Very nervous for the exam TODAY!!!

Reply 231

Babyblue

so guys. do you think a hess law will come? becuase there was one in the 3b paper. my teacher thinks there wont be hess law this time? :biggrin:

Reply 232

UnknownGirly

Good Luck everyone :smile:

Reply 233

ummm

Original post by Babyblue

so guys. do you think a hess law will come? becuase there was one in the 3b paper. my teacher thinks there wont be hess law this time? :biggrin:

I swear there's always a Hess' Law question?

I love Hess' law questions! And calculating enthalpy change! :biggrin:

Reply 234

danger-.-

guyz help me out plzz ! i get confused when it comes to periodic trends , i no the ionic raduis thingy tho not much , but the mp bp and stuff like that i get get all stuck ! help meh ! :wink:

Reply 235

This Honest

Original post by sabre2th1

What time is this exam? My timetable just says PM, it doesn't state an actual time..

Thanks

I start at 1:30 but some may start at 1PM
You should have checked with the school

Reply 236

This Honest

Couldn't come on yesterday evening, had a lot to do and still more this morning before I head off.

Good luck guys and please don't discuss the exam until 04:30 Wednesday!