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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: poohead on April 15, 2010, 09:00:22 pm

Title: vcaa Q help?
Post by: poohead on April 15, 2010, 09:00:22 pm: this comes from the 2002
exam 1, q.10

5.00 g of nitrogen is completely converted into an oxide of nitrogen. The mass of the oxide formed is 19.3 g.
The empirical formula of the oxide would be
A. NO
B. N2O3
C. NO2
D. N2O

any idea how i approach this? :-[
Title: Re: vcaa Q help?
Post by: the.watchman on April 15, 2010, 09:07:35 pm: Well,

$n(N):n(O)$

$= \frac{5}{14}:\frac{14.3}{16}$

$= 0.357:0.894$

$= 2:5$

Erm, what did I do wrong now...?
Title: Re: vcaa Q help?
Post by: Blakhitman on April 15, 2010, 09:40:50 pm: Quote from: the.watchman on April 15, 2010, 09:07:35 pm
Well,

$n(N):n(O)$

$= \frac{5}{14}:\frac{14.3}{16}$

$= 0.357:0.894$

$= 2:5$

Erm, what did I do wrong now...?

You're right, they copied it wrong!
Title: Re: vcaa Q help?
Post by: superflya on April 15, 2010, 09:42:58 pm: i assume option d would have to be $N_{2}O_{5}$
Title: Re: vcaa Q help?
Post by: Blakhitman on April 15, 2010, 09:43:47 pm: Question 10
5.00 g of nitrogen is completely converted into an oxide of nitrogen. The mass of the oxide formed is 19.3 g.
The empirical formula of the oxide would be
A. NO
B. N2O3
C. NO2
D. N2O5

from http://www.vcaa.vic.edu.au/vce/studies/chemistry/exams/chemex12002.pdf
Title: Re: vcaa Q help?
Post by: the.watchman on April 15, 2010, 09:45:23 pm: Good, phew!
I thought I was going mad :D

(This makes a strange 1900th post :D)
Title: Re: vcaa Q help?
Post by: poohead on April 16, 2010, 11:23:33 pm: my bad :s
sorry
thanks for the help :)