Chemistry: Post your doubts here!

[bravegirl123]

Could u e

there is no affect of the Cl-Cl bond or Br-Br bond here. The main bond here is H-Cl and H-Br. U should refer to there bonds to answer the question. Bond energies are diff according to the elements they are bonded to so we cant relate Cl-Cl and Br-Br to H-Cl and H-Br

could u please elaborate on that, i am still confused.

 

[cute97]

can someone help me with these this is my chem the question might be a piece of cake for any of u
http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s06_qp_1.pdf
Q 5, 6, 11, 33 the N=N bond point 2 can be right too, and 40
thanks in advance

 

[Abu mota]

paper 1:
s08: Q.6,8,27,29,30,38 http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s08_qp_1.pdf
w08: Q.21,29,30,39 http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_w08_qp_1.pdf
plz help me, ty.

 

[syed1995]

can someone help me with these this is my chem the question might be a piece of cake for any of u
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s06_qp_1.pdf
Q 5, 6, 11, 33 the N=N bond point 2 can be right too, and 40
thanks in advance

5 b .. whenever a state change occurs from liquid to gas.. the bonds are broken.. and hydrogen bonding is only present where H is joined with N, O or F.

6 A .. because of Hydrogen Bonding.. The IMF are high.. while to consider a gas to be an ideal gas the inter molecular forces need to be zero.

11 A .. because the Acid will react with OH- to decrease the concentration of OH- ions which will shift equilibrium to right hand side and more product forms...

33 D .. 2 Is wrong because Triple bond is in products and non-reversible reaction so that won't affect how the reactants react.. and N=N bond is present in N2H4 not triple bond.

40 B 1 is correct.. 2 is correct as 2 OH groups are present (OH) and -OH in COOH .. H bonded with O is hydrogen bonding, 3 is wrong since it will form a ketone from secondary alcohol.


I'd suggest that you revise the chapter on bonding from the book or ask your teacher to give you revision on the topic.. since your concepts on Hydrogen bonding seem to be a little weak

 

[syed1995]

>?

From the question's equation itself.

Replace R` with H.. since it's a Aldehyde.

R can be any alkyl group (CH3,C2H5)

So only possible answers are C and D.. as they are the only ones which contain the bonds Which I have shown in the above pic.

But D will be a product from a ketone as there are 2 R groups, 1 OH and 1 COO- Group attached to it! while we need only 1 R group for a aldehyde.. so answer is C.

 

[h4rriet]

paper 1:
s08: Q.6,8,27,29,30,38 http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s08_qp_1.pdf
w08: Q.21,29,30,39 http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w08_qp_1.pdf
plz help me, ty.

6. Use pV=nRT.
8. Volume is proportional to temperature at constant pressure. You can tell from pV=nRT.
27. Unreactive towards mild oxidising agents = tertiary alcohol. We can get only D from a tertiary alcohol.
29. B and C are not acidic; A is not chiral. That leaves D.
30. The acid used to make this ester is hexanoic acid. Only C shows a hexanoate.
38. Step 1 will give us the product so we won't need steps 2 and 3.

21. Any C=C bond breaks and is replaced with a C=O bond.
29. Draw propanone first, then break the double bond and add an H to the O and a -CN bond. The remove the CN and put CO2H in its place.
30. (30+30)-18(water).
39. Compounds 1 and 2 are formed by the reaction of C3H7 radicals. Compound 3 is formed by the reaction of a C4H9 radical with a C2H5 radical. These last can't be made if only propanone is used.

 

[ahmed abdulla]

From the question's equation itself.

Replace R` with H.. since it's a Aldehyde.

R can be any alkyl group (CH3,C2H5)

So only possible answers are C and D.. as they are the only ones which contain the bonds Which I have shown in the above pic.

But D will be a product from a ketone as there are 2 R groups, 1 OH and 1 COO- Group attached to it! while we need only 1 R group for a aldehyde.. so answer is C.

still confused between C & D

 

[ahmed abdulla]

(CH3)2CO + H2NNHC6H3(NO2)2 → (CH3)2C=NNHC6H3(NO2)2 + H2O
what is this rn ...? ...? it says that it require room temp among some list given ..
. but y not this >CH3CH2OH + KBr ¨ CH3CH2Br + KOH

 

[tanixx]

32 Which of the following solids contain more than one type of chemical bond?
1 brass (an alloy of copper and zinc)
2 graphite
3 ice
how is the ans 2 and 3 only?

 

[strangerss]

hey everyone alsallum alaykom , can any one please explain the answer in question 3 OCT/NOV 2005?P1

 

[ahmed abdulla]

Which pair of reagents will take part in a redox reaction?
A CH3CH2OH + concentrated H2SO4
B CH3CHO + Tollens’ reagent
C CH3CO2C2H5 + dilute H2SO4
D CH3COCH3 + Fehling’s solution

 

[strangerss]

Which pair of reagents will take part in a redox reaction?
A CH3CH2OH + concentrated H2SO4
B CH3CHO + Tollens’ reagent
C CH3CO2C2H5 + dilute H2SO4
D CH3COCH3 + Fehling’s solution

I think the answer is B , am I right?

 

[ahmed abdulla]

I think the answer is B , am I right?

but y

 

[Aymen Ezazi]

32 Which of the following solids contain more than one type of chemical bond?
1 brass (an alloy of copper and zinc)
2 graphite
3 ice
how is the ans 2 and 3 only?

because brass is a mixture of two metals so will have only metallic bonding between them, whereas graphite has covalent and van der waals forces between its atoms , and ice has covalent and hydrogen bonding..

 

[Aymen Ezazi]

hey everyone alsallum alaykom , can any one please explain the answer in question 3 OCT/NOV 2005?P1

can u plz attach the link with it

 

[Aymen Ezazi]

hey everyone alsallum alaykom , can any one please explain the answer in question 3 OCT/NOV 2005?P1

and Walaikum as salam..

 

[haha101]

http://papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Chemistry%20(9701)/9701_s07_qp_1.pdf

Q no 9 10 12 13 14 16 18 20 22 26 34 37 39 n 40 pleasee

 

[A star]

32 Which of the following solids contain more than one type of chemical bond?
1 brass (an alloy of copper and zinc)
2 graphite
3 ice
how is the ans 2 and 3 only?

brass (metalic bonding)
graphite(covalent,vandervaals)
ice(covalent,hydrogen bonding)
hope it clears it

 

[A star]

http://papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Chemistry%20(9701)/9701_s07_qp_1.pdf

Q no 9 10 12 13 14 16 18 20 22 26 34 37 39 n 40 pleasee

i think i answered ur queries

 

[Seewhysee]

Which compounds may result from mixing ethane and chlorine in the presence of sunlight?
1 CH3CH2Cl
2 CH3CH2CH2CH3
3 CH3CHClCHClCH3
Can someone explain this to me?