Edexcel AS Chemistry module 2 revision thread.
Chemistry discussion, revision, exam and homework help.
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both sub-atomic particles are responsible for the temporary dipole to be set up in the molecule, so yes, both protons and electrons, although i'm sure you could get away with saying just electrons.(Original post by raam001584)
so is it number of protons and electrons that affect size of van der waals? or just electrons -
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So for combustion are the 2 arrows always pointing down towards H2O and Co2. And for formation are the 2 arrows always pointing up from the elements?(Original post by Widowmaker)
depends on whether you're using enthalpy of formation/enthalpy of combustion values
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Factors Affecting Reactivity (or rate of hydrolysis):(Original post by hotboi01)
hey, i have a question..why are iodoalkanes more reactive than choloalkanes and bromoalkanes
1.) Polarity --> C-Cl os more polar than C-I, therefore a stronger attraction towards nucleophiles, one would expect a faster reaction.
2.) Bond Enthalpy --> decreases going down the group, C-I bond is most easily broken and should give faster reaction.
***Bond Enthalpy is the most dominant Factor***
You can shorten that depending on how many marks they want. If it were a 1 mark question, just mention the bond enthalpy being weaker down the group. -
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Not sure if these have been answered, but here goes...
i) Identify this isomer of C4H8(Original post by ARCHK0VEN)
One of the isomers of C4H8 reacts with HBR to give 2 different products, the major one of which is a chiral molecule.
But-1-ene
ii) Give the mechanism for the reaction of this isomer with HBr
Electrophilic addition
iii)why is the major product Chiral, but the minor one not?
It is a molecule with with four different groups, about a central carbon atom (a chiral centre). I don't think stereoisomerism is in AS, not 100% sure though.
iv) Why is the chiral product the major one, and the non-chiral the minor one?
The chiral product is major becuase with an unsymmetrical alkene, the hydrogen from the hydrogen halide always adds to the carbon atom carrying more H-atoms. Hence, but-1-ene + HBr --> 2-Bromobutane, not 1-Bromobutane (the majority of the time).
v) The major product of this addition reaction is found to be optically inactive, explain why?
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state the reagent and conditions, and draw the products of the hydrolysis of transbutene
give the name of the reaction and product between the reactants:
- propanamine and KCN
has any1 answered these? i might have missed it - but i'm stuck.
i hate revising this module! (it may even be worse than statistics!) -
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well the reaction to get propanamine is to heat the halogenopropane in a dry sealed tube with NH3 + ethanol. This is a nucleophilic substitution giving the (alkane)amine. (NH2)(Original post by Gabrielle)
state the reagent and conditions, and draw the products of the hydrolysis of transbutene
give the name of the reaction and product between the reactants:
- propanamine and KCN
has any1 answered these? i might have missed it - but i'm stuck.
i hate revising this module! (it may even be worse than statistics!)
The other reaction is KCN + ethanol + halogenoalkane, heating under reflux. This gives an (alkane) nitrile (CN), again this is a nucleophilic substitution.
