Edexcel CHEMISTRY DOUBTS!!!!

[Saladin]

Post 'em all here!!!!

I do Edexcel AS chemistry!

[Blizz_rb93]

Does anyone have any worksheets for Edexcel chemistry unit 3 practicals???

[ksitna]

yeah i dont really know what to study for unit 3 :/

[Blizz_rb93]

yeah i dont really know what to study for unit 3 :/

Here I just found this


1. Make a salt and calculate the percentage yield (hydrated nickel sulfate)
2. make a salt and calculate the percentage yield (ammonium iron(II) sulfate)
3. carry out and interpret results of simple test tube reactions
4. measuring some enthalpy changes
5. finding the enthalpy of combustion of an alcohol
6. finding an enthalpy change that cannot be measured directly
7. reaction of alkanes
8. reaction of alkenes
9. experiment to find the effect of electrostatic force on jets of liquid
10. solubility of simple molecules in different solvents
11. thermal decomposition of group 2 nitrates and carbonates
12. flame tests on compounds of group 1 and 2
13. simple acid-base titrations
14. oxidation of metal and non-metallic elements and ions by halogens
15. disproportion reactions with cold and hot alkali
16. iodine/thiosulfate titration and the determination of purity of potassium iodate(V)
17. reactions between halogens and halide ions/some reactions of the halides
18. factors that influence the rate of chemical reactions
19. effect of temperature, pressure and concentrations on equilibrium
20. reactions of alcohols
21. preparation of organic liquid (reflux and distillation)
22. preparation of a halogenoalkane from an alcohol
23. reactions of the halogenoalkanes.

But I need some worksheets to help me get the idea they want lol

[Saladin]

There is no need for worksheets. Just do the ppqs from Jan 04 to Jan 2010. That is more than enuf practice!

[Blizz_rb93]

There is no need for worksheets. Just do the ppqs from Jan 04 to Jan 2010. That is more than enuf practice!

Problem is, they change the syllabus so some stuff from 04 till about 08 wouldn't be included cause of syllabus change.

[Saladin]

Problem is, they change the syllabus so some stuff from 04 till about 08 wouldn't be included cause of syllabus change.

There is no real change. You can practice them without fear!

[Blizz_rb93]

There is no real change. You can practice them without fear!

Yes there is, there's some points that they stopped bringing in for the new syllabus
If there was no real change? then why did they bother in changing the syllabus ?

[Summer :]]

i have a question
why do we have to add the sulphuric acid slowly when preparing the bromoalkane from alcohol?

[ksitna]

i dont get how to calculate the percentage yield and error
does anyone have any notes on these?

[EVIL DOCTOR]

i have a question
why do we have to add the sulphuric acid slowly when preparing the bromoalkane from alcohol?

So it will not explode as reaction is exothermic

[Saladin]

i dont get how to calculate the percentage yield and error
does anyone have any notes on these?

How about you give a question, and I help you with it. You can post in the Edexcel CHEMISTRY doubts area.

[wrongaccount]

there is this point the syllabus that i dont understand please could someone answer this before the exam ??

"Carry out the preparation of an halogenoalkane from an alcohol and
explain why a metal halide and concentrated sulfuric acid should not
be used when making a bromoalkane or an iodoalkane."


why cant Concen. H2SO4 be used neither a metal halide ?

[Summer :]]

there is this point the syllabus that i dont understand please could someone answer this before the exam ??

"Carry out the preparation of an halogenoalkane from an alcohol and
explain why a metal halide and concentrated sulfuric acid should not
be used when making a bromoalkane or an iodoalkane."


why cant Concen. H2SO4 be used neither a metal halide ?

this point is wrong though :s we use concentrated sulphuric acid to make bromoalkanes!! and a metal halide
but the point might be referring of why it should not be used
because it releases many by products
such brome or iodine depending on which halogenoalkane you are making...and it releases sulphur dioxide

[Uchia]

Summer don't confuse the guy i'll tell you the right answer

sulphuric acid is a stong enough oxidising agent so a concentrated sulphuric acid couldn't be used because it will further get reduced it self and will oxidise the halide ion to form iodine or bromine resulting in now HI or HBr for the reaction with alcohol to form haloalakane.