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chapter 5.3

chapter 5.3

Postby Izzy007 » Tue Nov 05, 2013 9:09 am

Hi,
I just wanted to clarify a definition, "Normality", I'm struggling to get the concept of normality
as i don't recall hearing this term before. I have a science background and have sat the GAMSAT before.
can you please explain it in any better way then it is in the Gold standard book?
Also how important is this concept for the GAMSAT.
Please advise
thank you
Izzy007
 
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Re: chapter 5.3

Postby goldstanda3269 » Tue Nov 05, 2013 8:53 pm

"Also how important is this concept for the GAMSAT."
- They would never ask "what is normality?" or "calculate the normality" without first using the standard definition as presented in the book. Likewise they can present a new concept but as long as you are comfortable with dimensional analysis then you can follow many real GAMSAT questions to their solutions without knowing any specific formula.

Key points:

1) M = molarity = moles/liter

2) N = normality = equivalents of acid or base/liter

3) HCl has 1 acid equivalent; H2SO4 has 2 acid equivalents; NaOH has 1 base equivalent (i.e. OH-)


So if you have 2.3 M of HCl then it's the same as 2.3 N of HCl. Because:

2.3 moles HCl/liter * I equivalent of acid/ mole HCl and since moles HCl cancels, you get:

2.3 equivalents of acid/liter = 2.3 N HCl


Using the same logic, if it were 2.3 M H2SO4, because there are 2 reacting units of acid, it would be equivalent to 4.6 N H2SO4.
goldstanda3269
 
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Re: chapter 5.3

Postby goldstanda3269 » Tue Nov 05, 2013 9:06 pm

oh, btw, the book comes with 10 hours of online videos access. You should consider watching the video in General Chemistry about Units of Concentration.
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Re: chapter 5.3

Postby Izzy007 » Thu Nov 21, 2013 7:45 pm

than you, that makes more sense.
yeah i had a look at the video. Thank you
Izzy007
 
Posts: 3
Joined: Thu Oct 03, 2013 9:18 pm


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