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AS Chemistry Doubts

Z

zainab1661

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25 Use of the Data Booklet is relevant to this question.
2.76 g of ethanol were mixed with an excess of aqueous acidified potassium dichromate(VI). The
reaction mixture was then boiled under reflux for one hour. The organic product was then
collected by distillation.
The yield of product was 75.0%.
What mass of product was collected?
A 1.98g B 2.07g C 2.70g D 4.80g

I get the answer as B and it's wrong
 
P

Paparazzi478

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XPFMember said:
Assalamoalaikum wr wb!
Ok so they said, there's 1 mol of sodium azide..right?

from eqn 1, we know 2 moles produce 3 moles of nitrogen, so one mole will produce 3/2 moles of nitrogen and one mole of sodium...

now from eqn 2, we know 10 moles of sodium produce one mole of nitrogen, we got only one mole of sodium therefore how many nitrogen will be there..=> 1/10

total moles of nitrogen = 3/2 + 1/10 = 1.6 ;)
Click to expand...
awee arent you a little genius. anyway how many marks are you getting in p1 ?
 
perkypearl

perkypearl

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fasih58 said:
Why are you doing paper 11 ? Paper 12 is our..
btw leme try the question you've asked!
2. Find moles of CO2 and H2O Both would be 0.8

so CxHy + O2 ------> xCO2 + y/2 H2O

By mole - mole relation...
we have moles corresponding to 0.2 moles of Hydrocarbon... find for 1 Mole ... i.e 4 moles in each case..
so X = 4
and Y/2 = 4
y = 8

C4H8 ANSWER!

5. A all are C to Cl... will cancel
B ... It has dipoles.... C to O , H to C , H to C
C ... C to O , C to Cl , C to Cl *last 2 will cacnel each other
D Both are C to O and will cancel..
B ANSWER

7 Oxidition = GOLEH ( Gain of Oxygen, Loss of Electrons & Hydrogen)
Reduction = LOGEH ( Loss of Oxygen, Gain of Electrons & Hydrogen)
Easy way to remember = GOLI LAGI :p

11 A is correct, Cu+ and Cu2+ are obtained at end of reactions... so they are catalyst
B is straight away wrong, as Cu is oxidized so its Reducing agent
C in Reaction I Ag ppt is formed which darkens it ,,, wo light is absorbed in it...
D Ag is reduced*

13 C. its a fact... SiCl4 + H2O ---> SiCl2 + 4H+ (ion) + 4 Cl- (ion) 9.1 (i) of syllabus.. look at that

19. A its a FACT!

20 In such structures.. all junction points are chiral centres... except ones with double bonds! :)

21. If you can draw it you'll find that out... other wise cram it! ;) Draw it and you'll be left with some additional Hydrogen atoms needs to be justified with double bonds.... and its a Cis retinal... be careful with that.........
A cyclohexane ring alters the C:H ...

24 C-C double bonds = 2 ..
Hydrogen atoms required 4....
and moles of H2 required would be 2... 2 x 2 = 4

Same with bromine.... 2 Br2 = 4 atoms of bromine to dissolve double bond

28 29 30 PM me the answers when you get em!
Click to expand...

Thank you!! i have variant 11 ...
 
thunderingthunder

thunderingthunder

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In May June 2011 Q.20 it says what statement about acrylic acid is not correct?
A.Both bond angles are 120.
B.It decolourises Bromine.
C.It gives an orange ppt with 2-4 dinitrophenyl hydrazine.
D.Ir reacts with an alcohol to form an ester.
According to the mark scheme,the answer is C.Why is that?Acrylic acid consists of a carbonyl carbon so it should give an orange ppt with 2-4 dinitrophenyl hydrazine.shouldn't it?
 
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