Post by: jasoN- on November 09, 2010, 02:24:29 pm
Is this the equation? I can't find it in my textbook (check the states too please)
I'm only gonna remember this one, cos no way in hell I'm remembering superphosphate :knuppel2:
Also for calculations, can I do
n = CV
= answer (eg. no need to do n = 1 x 2)
Post by: toshibaj on November 09, 2010, 02:25:36 pm
Post by: Martoman on November 09, 2010, 02:26:42 pm
That equation looks logical enough so long as there is an 4 on the H2S04 which i'm sure is just a typo.
Post by: jasoN- on November 09, 2010, 02:27:43 pm
Also I was thinking, ammonium sulfate is a fertiliser, wouldn't it be solid then? Or it's used in a mixture or something, idk I'm not good with gardening :)
Post by: Martoman on November 09, 2010, 02:33:21 pm
Post by: scocliffe09 on November 09, 2010, 06:45:18 pm
You can also form solid (NH4)2SO4 as well - depends on how you make it.
Post by: kyzoo on November 09, 2010, 07:01:58 pm
Post by: stonecold on November 09, 2010, 07:04:01 pm
Post by: kyzoo on November 09, 2010, 07:05:27 pm
Post by: Martoman on November 09, 2010, 09:11:20 pm
Post by: jasoN- on November 10, 2010, 10:29:38 am
In the 2008 sample exam, Question 3ci, the table about change in colour.
The suggested answers (non-VCAA) says that for an increase in volume, the system becomes lighter green.
An increase in volume is equivalent to a decrease in pressure and according to Le Chatelier's, drives the forward reaction (low to high particles), hence it should become deeper green?
Also MC Q12 there's a typo, it should be 3.34 kJ / °C instead of 3.34 kJ / K
And is there an error in the 2009 VCAA exam solutions?
Question 2cii and 2ciii, they used 2 significant figures.
From the question, it should have been 3 significant figures. I used 3 and consequently had an 0.1 margin of error.
Unless they used the sig figs from part (a) which seems quite irrelevant (it is enthalpy value), they're wrong.
Thanks for any help
Post by: matt123 on November 10, 2010, 10:32:28 am
One of the many uses of H2SO4 is ammonium sulfate.
Is this the equation? I can't find it in my textbook (check the states too please)
I'm only gonna remember this one, cos no way in hell I'm remembering superphosphate :knuppel2:
Also for calculations, can I do
n = CV
= answer (eg. no need to do n = 1 x 2)
I always thought water was the other product.?
Post by: will74 on November 10, 2010, 10:53:52 am
Another question:
In the 2008 sample exam, Question 3ci, the table about change in colour.
The suggested answers (non-VCAA) says that for an increase in volume, the system becomes lighter green.
An increase in volume is equivalent to a decrease in pressure and according to Le Chatelier's, drives the forward reaction (low to high particles), hence it should become deeper green?
Also MC Q12 there's a typo, it should be 3.34 kJ / °C instead of 3.34 kJ / K
And is there an error in the 2009 VCAA exam solutions?
Question 2cii and 2ciii, they used 2 significant figures.
From the question, it should have been 3 significant figures. I used 3 and consequently had an 0.1 margin of error.
Unless they used the sig figs from part (a) which seems quite irrelevant (it is enthalpy value), they're wrong.
Thanks for any help
First...
An increase in volume decreases concentration of all particles therefore making a lighter green. Then, as you said the system will oppose the change and move to the right. BUT it will only partially oppose the change, as explained by Le Chateliers principle. Therefore overall, it will be a lighter green than before the external change was applied.
Second, 3.34 kJ / °C instead of 3.34 kJ / K....
They are both the same. An increase in One degree is the same as an increase in one kelvin..
e.g. 0 degrees to 1 degree = 273 K to 274 K
Third, not sure about that one, but if it should always be to the smaller number of sig figs you're using in your calculations as im aware, even if it uses an answer from above. But don't stress about it...VCAA allow +-1 error in sig figs and no marks off :)
Hope this helps.
Post by: jasoN- on November 10, 2010, 10:55:20 am
Post by: matt123 on November 10, 2010, 11:01:16 am
OH true, yep that makes sense. thanks
dooood
There is water as a product in the reaction.
Just thought id point that out
well im pretty sure there is
in the notes book :)
Post by: jasoN- on November 10, 2010, 11:03:45 am
Post by: matt123 on November 10, 2010, 11:05:38 am
you mean the ammonia one? i googled it just now http://wiki.answers.com/Q/What_is_the_balanced_reaction_equation_for_ammonia_and_sulfuric_acid
You are correct
im guessing the notes book is wrong then.
They say
2NH3 + h2s04 = (nh4)2.S04 + h20
lol?
Post by: jasoN- on November 10, 2010, 11:06:33 am
Post by: matt123 on November 10, 2010, 11:09:58 am
yeah that one isn't balanced lol
BTW
i found another reaction ( the correct one i think)
2Nh4OH + H2s04 = ( Nh4)2.S04 + 2h20
Post by: jasoN- on November 10, 2010, 11:12:30 am
Post by: matt123 on November 10, 2010, 11:13:41 am
yeah that looks right, but i'm not gonna remember a more complicated equation :D
True
but are you 100% sure
2nh3 + h2s04 = (nh4)2.S04? is correct?
Post by: jasoN- on November 10, 2010, 11:15:16 am
2NH3 (g) + H2SO4 (aq) --> (NH4)2.SO4 (aq)
Post by: Mao on November 10, 2010, 02:33:30 pm
yeah that one isn't balanced lol
BTW
i found another reaction ( the correct one i think)
2Nh4OH + H2s04 = ( Nh4)2.S04 + 2h20
Ammonium hydroxide (NH4OH) is completely different to Ammonia (NH3). Those two are very different things.
Acid-base reactions don't always have to produce water, so long as there is an acid that donates H+ and a base accepting H+, you have neutralization:
HCl + CH3COONa --> NaCl + CH3COOH
HCl + CO32- --> HCO3- + Cl-
CH3COOH + NH3 --> CH3COO- + NH4+ [note: this can be written as CH3COONH4, as it is an ionic compound]
NH3 + HCl --> NH4+ + Cl- [note: this can be written as NH4Cl, as it is an ionic compound]
(And as you learn more, acid/base reactions don't even need hydrogens to be donated/accepted!)
Post by: LinusX on November 10, 2010, 05:17:54 pm