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Ed excel Chemistry A2 12th June, Wednesday

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Original post by AS01
lol yeah. I came here only for today for past few weeks I was busy with bio. lol it was making me crazy! now its done! so glad!
lol u can say ester bond can easily be hydolysed by water

enthalpy change when one mole of gaseous ion dissolves in sufficient solvent to give infinitely dilute solution.
Enthalpy of solution?


enthalpy change when one mole of solid dissolves in sufficient solvent to give infinitely dilute solution.

Explain why the rate equation for gaseous reactions that use heterogeneous catalysts.... can be rate=k
(all compounds have order of zero)
Original post by AS01
well it was high coz the paper was easy. Hopefully we dont screw up this paper. You ready for this?


It was. I've been scoring well in the past papers so I hope so, had BIOL4 today so I've done no revision tonight!
You ready for Chem5?
Original post by AS01
yup!
ionic radius and charge on ion

Observation when COOHs reacts with Na2CO3?


fizzing, always :smile:

what about lattice enthalpy? are they also affected by ionic radius and charge?
and definition of Hsolution? :biggrin:
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Original post by Blob2491
It was. I've been scoring well in the past papers so I hope so, had BIOL4 today so I've done no revision tonight!
You ready for Chem5?


I had unit5 of bio. How was it? umm yeah I think I am.
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Original post by AS01
yup!
ionic radius and charge on ion

Observation when COOHs reacts with Na2CO3?


effervescence.

advantages/disadvantages of forming an ester from acid anhydride/acyl chloride rather than alcohol + carboxylic acid?
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Original post by StellaRawr11
fizzing, always :smile:

what about lattice enthalpy? are they also affected by ionic radius and charge?
and definition of Hsolution? :biggrin:


what if I say two observation? :tongue:
yes they are :smile:
enthalpy change when one mole of solid dissolves in sufficient solvent to give infinitely dilute solution.
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Original post by posthumus
enthalpy change when one mole of solid dissolves in sufficient solvent to give infinitely dilute solution.

Explain why the rate equation for gaseous reactions that use heterogeneous catalysts.... can be rate=k
(all compounds have order of zero)


because it depends on availability of active site and not on conc of reactants or gases.
example of heterogenous catalyst?
Original post by AS01
I had unit5 of bio. How was it? umm yeah I think I am.


unit 5 already? how was that
it was ok I hope!
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Original post by Blob2491
unit 5 already? how was that
it was ok I hope!


yeah! we had unit 5 before unit 4 lol! but unit 5 was the one I was scared about so glad its over :tongue:
Original post by AS01
because it depends on availability of active site and not on conc of reactants or gases.
example of heterogenous catalyst?


YES! :biggrin:

Iron(III) !

Give me a process (with conditions) to get from
Alkene ------> Acyl chloride

:tongue:


Also do I need to know about all that stearic acid stuff... & do you recommend I memorize the structure of all those big esters like glycerol
(edited 10 years ago)
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Original post by jethacan
effervescence.

advantages/disadvantages of forming an ester from acid anhydride/acyl chloride rather than alcohol + carboxylic acid?


its toxic. advantage reaction gives high yield of ester
what group do u change of ester while making margarine?
Original post by AS01
what if I say two observation? :tongue:
yes they are :smile:
enthalpy change when one mole of solid dissolves in sufficient solvent to give infinitely dilute solution.


well i would say turns lime water cloudy? as CO2 is produced :d but it may not be right
Hsolution and Hhydration has similar definitions im so confused by cgp xD
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Original post by AS01
its toxic. advantage reaction gives high yield of ester
what group do u change of ester while making margarine?


by transesterification, add methanol/ethanol to substitute the fatty acid chains.

how would you choose a suitable indicator for a titration?
(edited 10 years ago)
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Original post by posthumus
YES! :biggrin:

Iron(III) !

Give me a process (with conditions) to get from
Alkene ------> Acyl chloride

:tongue:


lol sorry for not making it clear. I want you to explain what catalyst is used for what process. Two examples.

use HBr this will give haloalkane then use NaOH under ethanolic solution to make primary alcohol. then heat under reflux to change to COOH and react with PCl5

Iodoform reaction equation for propanone?
Original post by jethacan
how would you choose a suitable indicator for a titration?


The range must lie on the vertical line on the titration curve (equivalence point I think this is called)

Don't worry they give you the range in the data booklet, and the pH of the end point which is the same as pKin
Original post by AS01
yeah! we had unit 5 before unit 4 lol! but unit 5 was the one I was scared about so glad its over :tongue:


ah sweet...it will be horrible :frown:
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Original post by StellaRawr11
well i would say turns lime water cloudy? as CO2 is produced :d but it may not be right
Hsolution and Hhydration has similar definitions im so confused by cgp xD


but that would be to check for the presence of CO2 i dont know if it will give u a mark. I will say disappearance of solid :smile:
haha for solution its enthalpy change when one mole of solid is dissolved in sufficient solvent to make infinitely dilute solution while for hydration its enthalpy change to dissolve 1 mol of gaseous ion in excess solvent to make infinitely dil soln :smile:
they try to trick u with gaseous part :tongue:
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Original post by posthumus
YES! :biggrin:

Iron(III) !

Give me a process (with conditions) to get from
Alkene ------> Acyl chloride

:tongue:


Also do I need to know about all that stearic acid stuff... & do you recommend I memorize the structure of all those big esters like glycerol


lol glycerol is just 1,2,3-propantriol. Others u dont :smile:
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Original post by Blob2491
ah sweet...it will be horrible :frown:


unit 5 is nightmare!!! I never liked it! started to like it a month before exam lol
How do u find it?
Original post by AS01
lol sorry for not making it clear. I want you to explain what catalyst is used for what process. Two examples.

use HBr this will give haloalkane then use NaOH under ethanolic solution to make primary alcohol. then heat under reflux to change to COOH and react with PCl5

Iodoform reaction equation for propanone?


Iron(III) is used in the haber process... and I think Vanadium (V) is used in the contact process

Yup exactly :biggrin: Your way is shorter I actually started off with H2/platinum catalyst.... then UV rays with chlorine

I2 + OH- -----> IO- + I-

CH3CH2OCH2 + 3I2 + 4NaOH ------> CH3COONa + CHI3 + 3NaI + 3H2O
:colondollar:

Go from aldehyde to Carboxylic acid.... without oxidization

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