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Chemistry: Post your doubts here!

AbbbbY

AbbbbY

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ahmed abdulla said:
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w12_qp_53.pdf

Question 2b(v) whats the conclusion
Question 3d & e
Click to expand...

iv-
The decomposition will complete when the plunger stops moving outwards. You'll heat and reheat till the point comes when the plunger stops moving outwards.

v- You've to record the volume of gas collected. You've already calculated how much volume of gas a fixed mass of copper carbonate will give you. You've to simply relate the two here and state that whichever volume is equal, or close enough, to the theoretical value for the given mass (calculated in iii) shows you which equation it is following.

3d
I haven't completed the table so idk if any of the other calculated densities are 1.154. If they are, simply equate the ratio of H2SO4/H2O (or the other way round) in terms of water added to the one which has 1.154.
I mean, (40+X)/60 = Volume of water that makes 1.154 from the table/volume of H2SO4 that makes 1.154 from the table.

If there's no valuee 1.154 in the table, do this:
Calculated Density = Mass of H2O + H2SO4 / Total Volume
Equate this to 1.154


1.154 = (60+X)/32.859+(1.003X)
Solve for X. I simple plugged it into my calculator saving me the time and got X = 140.23
X - volume originally added = volume required
140.23 - 40.00 = 100.23 cm3 required.

Please check the marking scheme and let me know if this is incorrect. The answer.


Explaining my 1.003X,

from the equation, we can see that 40g of H2O = 40.12cm3. So, 1g = 1.003 cm3.
Let me know if this doesn't make sense. I'm not good at explaining. :(

3e
mass error = 0.01/100 * 100 = 0.01%
volume error =
100g of H2SO4 = 54.765cm3
0.25/54.765*100 = 0.456%
 
S

sitooon

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AbbbbY said:
What question exactly are you talking about?
THere're no questions from the text book mate. That's precisely the point. -_-
Click to expand...
how comes ? the nmr stuff and inhibitor and bonds and all that stuff are there in our textbook
but the design and drug part is always new question which are not related to what you study in the textbook!!
 
AbbbbY

AbbbbY

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sitooon said:
how comes ? the nmr stuff and inhibitor and bonds and all that stuff are there in our textbook
but the design and drug part is always new question which are not related to what you study in the textbook!!
Click to expand...

I don't even have a text book. ^_^
 
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