AS Chemistry P2 Prep.

[oldfashionedgirl]

Yes. But be sure to show the bonds too (e.g. C-N triple bond) and chiral C atom if it's a 3 mark question.

for showing the C-N triple bond, i should just make 3 lines between them in the isomer too, right? like we do when writing it? i haven't really seen an isomer like that before...

 

[leosco1995]

for showing the C-N triple bond, i should just make 3 lines between them in the isomer too, right? like we do when writing it? i haven't really seen an isomer like that before...

Yeah, just three lines between the C and N would be enough.

 

[soccerprinc3]

what's the difference between Sn1 and Sn2 reactions?

 

[misof'tegame]

what's the difference between Sn1 and Sn2 reactions?

Sn1 reaction for tertiary haloalkanes
Sn2 for primary haloalkanes!
secondary haloalkanes undergo both Sn1 and Sn2 mechanism.

A CARBOCATION IS FORMED IN Sn1 Mechanism
but not in Sn2!

 

[soccerprinc3]

oh ok thanks...do you mind showing me a diagram of the mechanism if you have any?

 

[littlecloud11]

oh ok thanks...do you mind showing me a diagram of the mechanism if you have any?

In Sn2 mechanism a carbon intermediate is formed which is temporarily bonded to five other atoms or groups of atoms and carries a overall negative charge. In Sn1 mechanism the first reaction involving the formation of the carbocation is a slow process and the second step involving the formation of the final product is a faster process. The reaction rate for SN1 only depends on one factor, the conc. of the halogenoalkane. For SN2 the reaction rate depends on both the conc. of halogenoalkane and nucleophile present.

 

[farhan143]

i have question it does not involve past paper though....

1. Construct ionic half equation for:
a) PbO2(s) being reduced to PbSO4(s) in presence of of H2SO4(aq)
b) PbSO4(s) being reduced to Pb(s) in the presence of water.
c) Mow write the balanced equation for the reaction between PbO2 and lead in the presence of dilute sulfuric acid.

please someone EXPLAIN me the steps involved in getting the answer right...

THANK YOU!

 

[smartangel]

okay its kinda weird but i cant get this question right..the answer is 18..im getting 14..

 

[angelicsuccubus]

okay its kinda weird but i cant get this question right..the answer is 18..im getting 14..

im getting 18 both times.. Carbon has 6 electrons, H has 1 electron so in CH3CH3 its 6+3+6+3= 18 and in F has 9 electrons, so 6 + 3 + 9=18

 

[misof'tegame]

okay its kinda weird but i cant get this question right..the answer is 18..im getting 14..

Dont just count the number of electrons in the outer shell....it's the TOTAL number of electrons!
Carbon-6
3 hydrogens-1*3
Fluorine-9
Add them all...(6+3+9) you'll get 18!

 

[smartangel]

Dont just count the number of electrons in the outer shell....it's the TOTAL number of electrons!
Carbon-6
3 hydrogens-1*3
Fluorine-9
Add them all...(6+3+9) you'll get 18!

ohh yeah got my mistake! thanks

 

[smartangel]

im getting 18 both times.. Carbon has 6 electrons, H has 1 electron so in CH3CH3 its 6+3+6+3= 18 and in F has 9 electrons, so 6 + 3 + 9=18

yesh i was considering outer electrons only..thanks

 

[angelicsuccubus]

yesh i was considering outer electrons only..thanks

np

 

[mujtabashahnawaz]

ohh yeah got my mistake! thanks

Thats good ..

 

[smartangel]

when 50cm^3 of a hydrocarbon Y is burnt it reacts with exactly 300 cm^3 of oxygen to form 200 cm^3 of C02. water is also formed. deduce the equation for this reaction. answer: C4H8 + 6O2 → 4CO2 + 4H2O..please tell the how to work this one out..its frm chemistry coursebook.

 

[xhizors]

what is redox reaction ??
it is either: a reaction in which both oxidation and reduction occurs
or: a reaction in which either oxidation or reduction occurs ??

 

[smartangel]

what is redox reaction ??
it is either: a reaction in which both oxidation and reduction occurs
or: a reaction in which either oxidation or reduction occurs ??

BOTH oxidation n reduction occur.

 

[mujtabashahnawaz]

when 50cm^3 of a hydrocarbon Y is burnt it reacts with exactly 300 cm^3 of oxygen to form 200 cm^3 of C02. water is also formed. deduce the equation for this reaction. answer: C4H8 + 6O2 → 4CO2 + 4H2O..please tell the how to work this one out..its frm chemistry coursebook.

Take the ratio of the volumes, because mole ratio is volume ratio, then balance the moles of H2O. Then calculate how many C and how many H are there in the products. The no. of C and H will be the same in the hydrocarbon!

 

[mujtabashahnawaz]

what is redox reaction ??
it is either: a reaction in which both oxidation and reduction occurs
or: a reaction in which either oxidation or reduction occurs ??

In redox, reduction and oxidation take place at the same time!

 

[smartangel]

Take the ratio of the volumes, because mole ratio is volume ratio, then balance the moles of H2O. Then calculate how many C and how many H are there in the products. The no. of C and H will be the same in the hydrocarbon!

yeah but i cant seem to get the answer..could you do the working please?