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Chemistry: Post your doubts here!

daredevil

daredevil

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Eshika said:
yes it is ethanoic acid but how do u get the empirical formula that they have given to us ?
Click to expand...
look Ca2+ needs 2(-1) to balance it out ryt??
if we take two of ethanoic acids it gives us C4H6O4
if we take 2 butanedoic acid it gives us something with eight C and with mmethypropanadoic acid is the same case...
only ethanoic acid gives the correct formula. remember to use 2 acids not 1 to balance out the one Ca.
 
daredevil

daredevil

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Zarif009 said:
I appreciate it but thats not the right answer...

some reactions such as enthalpy change from the combustion of glucose can be obtained just by using a calorimeter so Hess's Law is not needed...
Click to expand...
i didn't say we definitely need Hess for all the enthalpy changes but it is always possible to solve these questions with Hess if nothing else works.
it is just a method. and one that applies to all so that makes it handy if u have a good grip on Hess's law u don't need to work with other methods and formulae and stuff just putt in a Hess's triangle and u got ur thing going. that's wat i am saying
 
Eshika

Eshika

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daredevil said:
look Ca2+ needs 2(-1) to balance it out ryt??
if we take two of ethanoic acids it gives us C4H6O4
if we take 2 butanedoic acid it gives us something with eight C and with mmethypropanadoic acid is the same case...
only ethanoic acid gives the correct formula. remember to use 2 acids not 1 to balance out the one Ca.
Click to expand...

ohh!! ok thnx alot!!!!
 
syed1995

syed1995

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1357913579 said:
anyone?
Click to expand...

3biIW.png


The product gets oxidized.. both the C=C bonds will be broken... CH2 forms CO2 + H2O .. .. CHR forms aldehyde .. and CRR` forms Ketone..

So final product becomes ..

3biQ1.png


Answer is 3.
 
syed1995

syed1995

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1357913579

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syed1995 said:
3biIW.png


The product gets oxidized.. both the C=C bonds will be broken... CH2 forms CO2 + H2O .. .. CHR forms aldehyde .. and CRR` forms Ketone..

So final product becomes ..

3biQ1.png


Answer is 3.
Click to expand...

thanks for ur try bro but i asked for november 2009 which u can see on my post please help me at that
thanks
 
Z

zackle09

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syed1995 said:
Y = Products formed with reaction with CN + acid .. = CH3+CH(OH)COOH

Z = Product formed after oxidation is = CH3CH2COOH ..

The only difference in both is that Y has one more O then Z. so the difference in mass is 16.
Click to expand...


oh i get it now.. thanks so much!
 
AbbbbY

AbbbbY

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daredevil said:
Q1's answer is C. from the data u can infer that 50 cm3 of O2 was used to burn 10cm3 of hydrocarbon (CxHy)
make up an equation for the unknown hydrocarbon for ur aid and u'll c that 1 mol of CxHy requires 5 moles of O2 to produce 3 mol of CO2. 6 O go into the CO2 and the remaining 4 (from 5 O2) go to the H2O which means that 4 H2O molecules were formed. so we have 8 H and 3 C thus the ansewr.

Q2's answer is bcz 2 mol of NaN3 make 3 mol of N2 which means 1 mol makes 1.5 mol of N2 directly. then the Na produced also makes N2.
wth 2 mol of NaN3 we get 2 mol of Na so with 1 mol we get 1 mol of Na.
10 mol of Na produce 1 mol of N2 so 1 mol produces 0.1 mol
so total N2 produced is 1.5 + 0.6 = 1.6mol

i don't get q10 so if u get an answer for that tag me ^_^
Click to expand...


Q10:

Kp = ((2/3)^2)/(1/3)

= 4/9 / 1/3
= 4/9 * 3/1
= 4/3

Units: atm*atm/atm = atm
 
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