Qualification > Sciences
CHEM AND BIO HELP AND TIPS HERE
Baladya:
http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Jun/0620_s09_qp_3.pdf
Question number: 9) b)
I'm good in chemistery but my biggest nightmare is statiochemtry, so plz can u explain how to do in a baby-simple way :D ;D
thx ;)
holtadit:
SO write the equation out :
Al4C3 + H2O = Al(OH)3 + CH4 We know that H2O was in excess so ignore it for now and compare the moles of each substance
l l l
l l l
0.03 moles 0.12 moles 0.09 moles
then look at the ratio of moles i.e. 0.03:0.12 (which can be simplified to 1:4) and 0.03:0.09 (which can be simplified to 1:3)
Thus u now have 1Al4C3 + ?H20 = 4Al(OH)3 + 3CH4
Now compare the no. of atoms as per the new balancing an we just need to add a 12 before H20 to balance everything out. DONE !!
holtadit:
Okay Nid need your help again.
2008 Summer Paper 6 Question 4 e ii
I think the MS is wrong. If you use a greater volume of a solution shouldnt the conc. of that particular solution be LOWER ?
I keep getting questions regarding changes in concentration & volume wrong. Is there a formula/principle linking these two. Is there anything in your AS/A level textbook that can help me out with this stuff.
nid404:
Twice as much soln of KMNO4 ws used for A ws as compared with B.
More the amount of KMNO4 required to complete the react means more no of moles of the substance(that is more conc )
More of it required for A, so A is more concentrated...
Get this right....conc of KMNO4 used is same for both....so the greater the volume of KMNO4 used, greater the conc of te conc of the substance
holtadit:
Thanks I got it !
But is there any principle/formula for all of this. Even if it a level stuff I am willing to learn and understand it.
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