Edexcel Unit 1 June 2011 Discussion.

I hope I'm not the only one who thought the multiple choice was horrible. I probably got 10 on that. The rest of the paper was fine, though I thought I kept repeating the same thing for the last few questions on metals.
Enthalpy change = +77 something?Cant remember, but it was endothermic.

Discuss!
Grade boundaries = lower than June 2010 I hope.. otherwise i've missed out..

Yeah I also got the enthalpy as + 77.


For the structure of metals I wrote- They are giant and consist of a lattice which is a repeat structure.

For bonding I wrote- Delocalised electrons surrounding positive ions causing attraction.


What did you get for the 3 reasons why the enthalpy may be different?

Disadvantages of incomplete combustion?

Disadvantages of complete combustion?

Was the maximum yield of mgcl2 1.52 grams?

Did you get 0.016 and 0.033 for the moles?

The reactions of the free radical substitution were :

Initiation:

cl2 forms 2 chlorine free radicals, you must show the 2 half arrows.

Propagation:

ch4 + cl --> ch3 free radical + hcl

ch3 free radical + cl2 ---> ch3cl + cl free radical.

Termination:

ch3 free radical + cl free radical ---> ch3cl.

How ethane is formed:

ch3 free radical + ch3 free radical ---> c2h6.

Ionization energy:

Sulphur has a lower ionization energy than Phosphorus because it has 2 electrons in one of its 2P orbitals which repel each other making it easier to lose one of them.

what did you write for the expermiental one , the four mark that said describe the apparatus you would use ( the enthalpy question ) and befiefly how you would take measurements or something. This was the question before asking about the three reasons.

Most people i know put that they pat dried the crystals etc, however the question didnt ask to make a new crystal, the question was how would you go from hydrated copper sulphate --------> aqueous copper sulphate ( which is in a liquid form) so what i said what that you get a bunsen and a tripod, put the crystals in a beaker and heat. record the temperature before and after and work out the enthalpy change that way...... you ?[/QUOI wrote

Yeah you got it right.

really?? wahooooo im jumping in joy !! did you put the same ?

for that question I wrote record the mass using Balance then use calorimeter to measure temperature change , and also we have to know/record the number of moles of coppers something and also have to know its spacific heat capacity.
How much I'll get for that?

I wrote polystyrene cup inbeaker, but known volume of water in it.
measure temp every 30 s for 1 min. at 2.3 min add known mass of crystals, measure temp every 30s for 5 more min. plot graph, extrapolate and measure temperatura change.
use to find enthalpy

dont know if its completely right but they will give me some marks i hope ! :P

for the questions about the difference between experimental data and the one in data book ?
what didi people put ?


disadvantages of incokmplete
less energy released than during complete combustion
CO binds to haemolgloobin so reduce amount of O2 in blood

dis of complete,
Co2 is greenhouse gas, abosrb IR radiation when assymetrical streching or bending of bonds , therefore causeing global warming.
increasing leveles of Co2 in air due to anthropgic chanege

I also talked about sulfur oxide in complete combustion, I was not sure whether they were asking for cmplete combustion using the formula they gave us or in general.

for that question I wrote record the mass using Balance then use calorimeter to measure temperature change , and also we have to know/record the number of moles of coppers something and also have to know its spacific heat capacity.
How much I'll get for that?

and what about for the other ones ? what didi you put ?
the oen about 3 difference between experimental and data book ?

i said use a beaker, lol stupid me, the beaker is a poor insulator LOL

That question was baffling because I restricted so many things. I put :

Incomplete reaction,
Some energy is released to surroundings regardless of insulating,
Some energy is absorbed by the insulator rather than going towards the reaction.

I mentioned not all of the reactants react does this count?