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Aqa chem 4/ chem 5 june 2016 thread

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Advantage - can melt/burn the waste, produce heat energy to generate electricity.
Disadvantage - releases toxic gases.
The other two main ones would be recycling and landfill.

GOOD LUCK guys!!!

Original post by cutelady

I AM GOING TO FAIL!!
Basically I am good with everything apart from when they ask you to deduce a structure of an isomer with the molecular formula "C6H12O2" i take too long on the questions, and I always end up getting them wrong! Does anyone have a quick method of working these out?

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Exactly the same with me :frown:

Reply 503

dnan

Why does water only very slightly dissociate?

Reply 504

man i

can someone help me with )#

2cii_ jan 2010

Calculate the pH of the buffer solution formed when 10.00 cm3 of0.100 mol dm–3 potassium hydroxide are added to 25.00 cm3 of 0.410 mol dm–3ethanoic acid

i worked out the moles and and the numbers of mols after the XS etc divided each by the total volume and that came out as being wrong. Why is it that you dont divide by the total volume?

Reply 505

khuman97

can someone please explain june 11 2ci and 2cii i think they were the two buffer questions dont make sense to me thanks :smile:

Reply 506

heyitskim

Guys how do you draw R2CH2 and R3CH? I've never understood how to draw them.

Reply 507

Sniperdon227

Original post by man i

even though its a buffer you look at the reactants its a weak acid with a strong base, determine which is in excess and decide what to do; if excess acid its a slightly longer method than if the base was in excess

Reply 508

man i

Original post by Sniperdon227

i just looked at what i done and i misread what my numbers,due to my writing not being neat so placed the wrong numbers in so yeah i get what i done wrong thanks by the way.

Reply 509

SubwayLover1

Original post by heyitskim

Guys how do you draw R2CH2 and R3CH? I've never understood how to draw them.

So for R2CH2 - the R means any other group however the most important thing is to look at the splitting pattern - if had has a triplet - it must be attacthed so a CH2 so it will become RCH2CH2

Reply 510

Fibsy

Let's see how this exam goes with a sleep deprivation headache from 4 hrs sleep (exam stress stops me sleeping) :smile:

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Reply 511

Lilly1234567890

When the concentrations of A and B were both doubled, the initial rate increased by afactor of 4. Deduce the overall order of the reaction.

HELP PLEASE

Reply 512

Sniperdon227

Original post by Lilly1234567890

When the concentrations of A and B were both doubled, the initial rate increased by afactor of 4. Deduce the overall order of the reaction.

HELP PLEASE

is it the overall order2?

Reply 513

Sniperdon227

in amino acids like H2N-c-cooh and the other groups does it have ionic bonding or is it only when a zwitterion it has ionic???

Reply 514

Charco63

In what circumstances do you divide them both by the total volume, or the excess by total volume?

Reply 515

man i

yeah i sort of messed up the equation because of my bad set up, i got the salt etc and done molex1000/v to get conc for both the left over solution and salt and then messed up my number by using 9.25x10-3 rather than my worked out concentration. so i shouldve got it right either way.

just another question i wanted to ask for KC if the volume of the container increases say 1.5dm3 to 3.0dm3 it does not effect the kc does it or the conc right or does it effect the conc only. im really confused on these for some reason