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southeastnigga
Can anyone remind me what the last question or the question before the last was about? It it was one of the couple of questions I struggled, but I've already forgotten about it due to being happy with the paper overall lol.


Last questions was electrophilic addition between cl2 and a alkene, if that helped.
Reply 41
Aeon Prince
for delta H r was your enthalpy sign positive or negative?


oh negative sorry
algérie_mon_amour
I've put because the reaction is exothermic, so the catalyst is absorbing the heat. What about you?


Lol I put that too, as a wild guess, if it's correct woohoo.
beckyburch
Yes, bcause CO2 wasnt a product of the reaction

The equation i used said is in the nelson thornes book. And co2 isnt produced even if you used cl2?
Reply 44
beckyburch
Where was that???? it was the Cl- ions wasnt it???


i went with Cl2, the equation was something like Cl2 + H2O = H+ + cl- + HClO and the question said when you add sodium hydroxide the colour disappears. so if you add NaOH, the OH- would react with the H+ creating H2O, since it was a reversible reaction at equilibrium by increasing concentration of reactants and decreasing conc of products you'd shift equilibrium to the right, more Cl2 is used up and therefore the colour disappears

(feel free to correct as thats just my theory)
oh and SO2 doesnt make H2SO4, it makes H2SO3 when reacted with water, its sulfur trioxide that reacts to produce H2SO4 :biggrin:
Reply 45
algérie_mon_amour
I've put because the reaction is exothermic, so the catalyst is absorbing the heat. What about you?

That seems more reasonable then what I said which was increases rate of reaction.
Reply 46
gcseangel
The only reagent I could remember was benedicts I said turns brick red with aldehyde And stays blue with ketone. Yay I wrote that too. I said cl2 u? In the long question it asked about biofuels what did u write? And there was a question which wasvasking for colour I think the page it asked abt what type of alcohol this?!?



Benedicts is for sugars in biology....
Fehlings is simular. thats the copper one....
Reply 47
So2 + H2o + 1/2o2 -->h2so4
Marcus_Q
H-H bond enthalpy I got 464 maybe? It was in the 400s... Delta H r enthalpy change I think it was one thousand and something, can't remember what.


I didn't get 464, I got 900 ish :o: I thought that was a bit big for H-H:rolleyes:
Hr , how did you do it? because I got confused with that one =@
I got something like 1400...
Casshern1456
So2 is collected and use to make h2so4..you know..add water. For catalyst being hot, i don't know, the only question to baffle me on the paper.:biggrin:

EDIT: just incase you wrote so2 down and tried working it out. the extra oxygen came from the air.

so2 + h2o + 1/2o2 = h2so4


did we need to give an equation when it said "use of so2?"
Reply 50
Casshern1456
It's not wrong.

r you sure as it said the reaction occurs with sunlight so the product would be hcl and 02 like aeon said. Looks like we both lost the mark lol
algérie_mon_amour
I didn't get 464, I got 900 ish :o: I thought that was a bit big for H-H:rolleyes:
Hr , how did you do it? because I got confused with that one =@
I got something like 1400...

lol i completely guessed delta H r and got 1400 something too but i didnt know if it was meant to be negative or positive so i put a positive sign :frown:
Sooo annoyed with the paper! :rant: weeird questions compared to all the past papers i've done. What is it with January exams?! :shifty:

Everything i revised so well did not come at all except the 2 mechanisms :cry2: :argh:
Reply 53
Overall i thought the paper was good, however i thought that in June and got a C! There were a couple that stumped me. Forgot what SO2 could be used for, and was the catalyst heated so the reaction would have enough kinetic energy to react? And then remained hot because the reaction was exothermic...

:s-smilie:
Reply 54
Aeon Prince
did we need to give an equation when it said "use of so2?"[/QUOT
no it didn't say nething like that
Reply 55
So what was the terminal bit of the free radicals substitution
I couldn't make one that fitted C3H7, I had C3H7 and Cl as my radicals
where did i go wrong? :confused:
And what was that Mr question about?! about the traces of CO2?!

And does anyone else think they made a mistake with the free radical sub question. On the termination step, they stated that the product formed will have the molecular formula of C3H7.. wasn't it supposed to be C3H7Cl ?
evelyn_92
So what was the terminal bit of the free radicals substitution
I couldn't make one that fitted C3H7, I had C3H7 and Cl as my radicals
where did i go wrong? :confused:

it said c3h7 was the empirical formula so the molecular formula if you used the right free radicals would have been c6h14
i think
How idiot I am, for the first question I've put Hydrogen was a reducing agent and then crossed it out and put catalyst! :facepalm:
time.to.dance
And what was that Mr question about?! about the traces of CO2?!

And does anyone else think they made a mistake with the free radical sub question. On the termination step, they stated that the product formed will have the molecular formula of C3H7.. wasn't it supposed to be C3H7Cl ?

it said the empericial formula was C3H7 so the molecular formula would have been C6H14 I think the ones you were supposed to use were
ch3ch2ch2 + ch3ch2ch2

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