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2002 - Written Paper - Q4(b)

someone11

Posted 24 May 2006 - 10:48 PM

Hello

yea sorry i get it now, it was late i was rambling.

I actually havea genuine question about 2002, question 4b)

The reaction FeS and FeCl -----> H2S + FeCl


In FeS iron is sometimes present as an impurity. Name the other product which would be formed in the reaction with dilute hydrochloric acid if iron metal is present as an impurity.

The answr is hydrogen but how?????

Pyrefly

Posted 25 May 2006 - 11:54 AM

Well..im nto any good at chemistry....but i dont know where the 0.02 moles came from for the H2SO4....

moles= concentration * Volume


both acids have the same concentration and volume..so they surely have the same number of moles...

ya if someone would help out it be nice..im a tad confused here too

Pammy

Posted 25 May 2006 - 01:11 PM

QUOTE(Pyrefly @ May 25 2006, 11:54 AM) View Post


both acids have the same concentration and volume..so they surely have the same number of moles...



Yeah I'd agree with that

Someone11, you confused me a wee bit sad.gif so I'm gonna wait for someone smarter to come along tongue.gif

Michael

Posted 25 May 2006 - 03:51 PM

Can you give the question in context (or PM me it) because I don't quite understand what you mean.

xpurple_starsx

Posted 25 May 2006 - 04:08 PM

This is a bit of a guess so check with someone else but... has it got something to do with the fact that there are 2H in H2SO4, whereas most other acids only have one H like HNO3? That might alter the number of moles reacting?

I'm not sure but I remember being told that H2SO4 is different because of the 2H.

Sorry if that's utter rubbish!

Nathan

Posted 25 May 2006 - 04:15 PM

that is true...i can't remember what difference exactly the 2nd H makes though....i've got a feeling it's got something to do with how quick it reacts...can't remember though huh.gif

Ali89

Posted 25 May 2006 - 04:20 PM

isn't the H2 part of H2SO4 called it's something power? you know, you use it in N1C1V1 = N2C2V2... i had a feeling it was called the neutralising power? or power of the acid?



Michael

Posted 25 May 2006 - 04:54 PM

Ok, I think I know what you're trying to get at but if im wrong tell me.

Lets take 2 equations one involving sulphuric acid and one involving hydrochloric acid:

NaOH + HCl ----> NaCl + H2O In this equation 1 mole of alkali neutralises one mole of acid.

However if you take the balanced equation for H2SO4 it looks like this:

2NaOH + H2SO4 -------> Na2SO4 + 2H2O

Technically they require the same moles of alkali as the ratio is still 1:1 however the power of the sulphuric acid is 2. Therefore as there are 2 H+ ions there are 2OH- ions but the ratio remains the same.

Nathan

Posted 25 May 2006 - 05:08 PM

Or, if you take 2001 section A Q3,

Answer is D because

PCVacid = PCValkali
implies.gif 2x0.3x0.01 = 1x0.3x0.02

mynameisearl

Posted 25 May 2006 - 07:27 PM

if you can give the full question maybe someone can help?

thegift_guitar

Posted 26 May 2006 - 04:12 PM

I did that question recently. All i did was look at the diagram there, and there were bubbles cumin out, and if u look at the equation the only gas that could be formed is hydrogen. Thats all there is to it really. Plus its only 1 mark.

someone11

Posted 27 May 2006 - 12:01 PM

QUOTE(thegift_guitar @ May 26 2006, 05:12 PM) View Post

I did that question recently. All i did was look at the diagram there, and there were bubbles cumin out, and if u look at the equation the only gas that could be formed is hydrogen. Thats all there is to it really. Plus its only 1 mark.


There is no diagram. huh.gif sad.gif

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