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AQA - Unit 5 - Energetics, Redox and Inorganic Chemistry

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you know for non-rechargable battery cells..
do wejust need to know the half equations andhow to write the cell emf?
what about the electrolyte used for it?
or do we need to know everything for each type like the advantages and disadvantages aswell?

Reply 601

strawberry_cake

ummm

9 You are required to plan an experiment to determine the percentage by mass of sulphate ions
in some solid waste made up of the three compounds silicon dioxide, sodium carbonate and
magnesium sulphate.
You are provided with dilute hydrochloric acid, a solution of barium chloride and simple
laboratory equipment. (Hydrochloric acid reacts with carbonate ions and prevents the
precipitation of barium and magnesium carbonates.)
(a) Outline how you would extract the sulphate ions from the solid waste and convert the
extracted sulphate ions into a precipitate of barium

Do we need to know how to answer this q? Its in the june03 paper and I have no idea :s-smilie:

Reply 602

Arab_Empress

Original post by BethBeth

No probs, hope your revision is going okay! :smile:

Have you done question 7 b ii) ?

infact nevermind i got it :smile:

(edited 12 years ago)

Reply 603

starburst92

Original post by strawberry_cake

June 03 is from the old spec so I really doubt this will come up :smile:

Reply 604

clairecourtney

do we need to know about adsorption and desorption of homogeneous catalysts?
it doesn't say anything about it specifically in the spec and it isn't in the textbook as far as i can see but it has been on a few practice questions i've done

Reply 605

Sparkly-Star

Original post by clairecourtney

It's from unit 2, so I'd just briefly go over it. :smile:

Reply 606

InItToWinItGetIt?

Why are there 2 MNO₄- in the overall equation for autocatalysis?

Reply 607

jamest92

Original post by InItToWinItGetIt?

Why are there 2 MNO₄- in the overall equation for autocatalysis?

In the MnO4- equation there are 5 electrons and in the C204 2- there are 2 electrons, you want the same number of electrons so you times the MnO4- one by 2 to get 10 electrons, this means everything has to multiplied by 2 so there is 2 MnO4-

Reply 608

BethBeth

Original post by clairecourtney

Adsorption only happens on heterogeneous catalysts, where reactants are adsorbed usually by a metal catalyst, react and then are released...

Homogeneous catalysts are in the same phase as reactants (usually aqueous) so surely they can't be adsorbed?

(Correct me if I'm wrong people).

Reply 609

Arab_Empress

Does anyone have a list of the acid-base reactions:
like Na2O + P4O10 .. etc

:smile:

Reply 610

teddyWS

is there a possibility of M=QC/\T coming up? (from unit 2)

Reply 611

JK471993

Original post by teddyWS

is there a possibility of M=QC/\T coming up? (from unit 2)

Q=mcdT.

It can come up

Reply 612

kerb123

Original post by Arab_Empress

Does anyone have a list of the acid-base reactions:
like Na2O + P4O10 .. etc

:smile:

At the bottom

http://www.a-levelchemistry.co.uk/AQA%20Chemistry/AQA%20A2%20Chemistry/Unit%205/Unit%205%20Past%20Papers%20and%20Revision%20Aids/Unit%205%20summary%20home.htm

Reply 613

strawberry_cake

Original post by starburst92

June 03 is from the old spec so I really doubt this will come up :smile:

ohh okies, thanks :smile:

Reply 614

xX.Sabeel.Xx

yep but got to remember to get Q you have to do
deltaH x number of moles

Reply 615

usmana

how do you work out h from q=mct

Reply 616

strawberry_cake

so much to do :frown:

Reply 617

jamesl1

hey in thermodynamics ive read that smaller ions lead to bigger lattice formation enthalpies due to the charges being closer together etc, but ive also read that with bigger anions you get larger enthalpies due to being distorted by the cation and hence there is slight convalence.

does anyone know which is correct ? :tongue: