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Chemistry: Post your doubts here!

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The answer should be D. The -OH on left won't be oxidised by cold, dilute KMnO4, but the alkene would be oxidised to a diol. When hot, conc. KMnO4 is used, that -OH group is oxidised to a ketone and the carbons with the double bond in the ring(alkene group) would be oxidised to Carboxylic acid and a ketone respectively.
 
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can someone please explain Q1..c i. we get 0.04 moles of acid and alcohol,,dont we subtract it from 0.1 to get moles at equilibrium?
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s11_qp_22.pdf
No. of moles of NaOH is 0.04 as we calculated earlier meaning (0.1 - x) = 0.04
Because alcohol was the reactant and equilibrium concentration of reactant is given by:
(initial concentration - x) so (0.1 - x) = 0.04 and
therefore x = 0.06
So concentretion of acid and alcohol is (0.1 - x) = (0.1 - 0.06) = 0.04
:)
This paper reminds me of last year, I gave this very paper in the exam last year in AS
:)
 
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No. of moles of NaOH is 0.04 as we calculated earlier meaning x = 0.04
So concentretion of acid and alcohol is found out by
= (0.1 - x)
= (0.1 - 0.04)
= 0.06
:)
This paper reminds me of last year, I gave this very paper in the exam last year in AS
:)
haha so does your answer match with the marking scheme? :p
coming back to the question.. i really dont get it. could you please explain why have they taken 0.04 for the acid and alcohol.their equilibrium moles should be 0.06.?
 
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haha so does your answer match with the marking scheme? :p
coming back to the question.. i really dont get it. could you please explain why have they taken 0.04 for the acid and alcohol.their equilibrium moles should be 0.06.?
I made a mistake earlier i corrected it check the first post...
Btw, i dont remember my solution from last year but i do remember that i got Kc = 2.25 so i must have done it right there
:)
 
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Hey i have a doubt related to "Hess's Law calculations"
I always get confused what equation's enthalpy change to minus and what to plus - so can anyone please explain Hess's Law calculations ? ^^
 
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i dont get why we use excess air when converting SO2 to SO3 in the contact process......i know it shifts the equilibirium shifts to the right but i dont get why...??????:confused:
 
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i dont get why we use excess air when converting SO2 to SO3 in the contact process......i know it shifts the equilibirium shifts to the right but i dont get why...??????:confused:

According to the Le Chateilier's (dunno how to spell it :p), so according to the principle if any change in the factors which affect the equilibrium is altered than the reaction behaves in a way which opposes the change and tries to attain eq. Sooo if you add excess O2 the concentration of the reactants increases and so the equilibrium shifts to the right to produce more products so they reaction will come to eq. again, hence increasing the conc. of the products so SO3 increases!
 
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Aoa,
Q1:
Mr (TiO2) = 47.9 + 16 + 16 = 79.9
Mr (FeTiO2) = 55.8 + 47.9 + 3(16) = 151.7
FeTiO3 ---> TiO2 + FeO
molar ratio b/w FeTiO3 and TiO2 is 1:1
so
151.7 g of ore gives 79.9 g of TiO2
1 g of ore gives (79.9 / 151.7 g) of TiO2
19 tonnes of ore will give
= 19 * (79.9 / 151.7 g)
= 10 tonnes
So, A is the answer!
:)

Q4:
The hydrogencarbonate anion is (HCO3)-1
Total electrons = 1 of H + 6 of C + 3(8) of O + 1 extra electron due to -1 charge
= 1 + 6 + 24 + 1
= 32
So, C is the answer!
:)

Q22:
B and C have two similar groups (methyl) attached to one side of carbon having double bond, that means there cannot be cis-trans isomers for these
A will form cis-trans isomers if 1 H is substituted on the R.H.S but it will not have a chiral centre
D already has cis-trans isomers, and it will have a chiral centre at the RED carbo atom if one of the BLUE hydrogen is replaced by halogen!
CH3CH=CHCH2CH3
So, D is correct!
:)
 
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Assalamualaikom

A garden fertiliser is said to have a phosphorus content of 30.0% ‘P
2O5 soluble in water’.

What is the percentage by mass of phosphorus in the fertiliser?

A
6.55% B 13.1 % C 26.2% D 30.0%
Can anyone please answer this with an explanation? Thank you. :)
 
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W.salam,
Mr(P) = 31
Mr(P2O5) = 2(31) + 5(16) = 142
In 100 g of fertiliser, there is 30.0% P2O5
That means mass of fertiliser is
= (100/30) * Mr(P2O5)
= (100/30) * 142
= 473.3 g

% of phosphorus in fertiliser is
= (2*31 / 473.3) * 100 [(2*31) because there are 2 atoms of P in one molecule of P2O5 ;) ]
= 13.1 %
So, A is the answer!
:)
 
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