Year 12s: what will be the first way you research your future options? >>

GCSE Chemistry Unit 3 (C3)

annie79

Anyone have any predictions for 6 markers for the C3 exam tomorrow? (19th June)

Scroll to see replies

Reply 1

Angelo12231

Original post by annie79

Anyone have any predictions for 6 markers for the C3 exam tomorrow? (19th June)

im pretty good with these... il tell you when ive revised

Reply 2

Parallex

A titration could easily be one of them. ^^

Reply 3

Angelo12231

Original post by Parallex

A titration could easily be one of them. ^^

i believe that was last year :frown:

would have been simple

Reply 4

Parallex

Original post by Angelo12231

i believe that was last year :frown:

would have been simple

Mmm yeah, that's what me and my friend said. However, it's such an easy 6 mark for them to put in.

Er... Electrolysis could be a 6 marker (if so, it won't be the easy electrolysis as that was in C1)

Ethanol production came up last year if I recall correctly, but I wouldn't be surprised if it came up again.

Making esters and how soap works could also be.

Reply 5

RobertMichael

There will be one topic from Electrolysis( mostly the one that involves half-equations) and The Haber Process are more likely to turn up.

Reply 6

LeEastafrican

i would put my money on soaps and esters to come , maybe margarine?

Reply 7

LeEastafrican

can someone explain to me what dehydration means, is it as simple as removing water from something...

Reply 8

annie79

Original post by LeEastafrican

i would put my money on soaps and esters to come , maybe margarine?

hmm, maybe soaps and esters, but margarine i would say would be a 3-4 mark question.

Reply 9

annie79

Original post by LeEastafrican

can someone explain to me what dehydration means, is it as simple as removing water from something...

basically, the ethanol is dehydrated in the presence of a CATALYST (usually aluminium oxide) to form ethene gas and water
the equation for this is:
Ethanol --> ethene + water
(C2H5OH --> C2H4 + H20)

Reply 10

LeEastafrican

Original post by annie79

basically, the ethanol is dehydrated in the presence of a CATALYST (usually aluminium oxide) to form ethene gas and water
the equation for this is:
Ethanol --> ethene + water
(C2H5OH --> C2H4 + H20)

thank you, almost forgot the catalyst.

Also for the margarine,
a hydrogen atom is added to the carbon double bond of unsaturated oil,
is it also using a catalyst? and what is the process called? is it something like hydrogenation, need clarification

Reply 11

Parallex

Original post by LeEastafrican

It's called Catalytic Hydrogenation, hydrogen atoms are added to unsaturated oil to make it a saturated fat, as the double bonds are converted to single bonds.

(edited 9 years ago)

Reply 12

LeEastafrican

Original post by Parallex

It's called Catalytic Hydrogenation, hydrogen atoms are added to unsaturated oil to make it a saturated fat, as the double bonds are converted to single bonds.

Catalytic Hydrogenation, so it does involve a catalyst, do we have to know the name of the catalyst like the one involved in the dehydration of ethanol ?

Reply 13

Parallex

Original post by LeEastafrican

Catalytic Hydrogenation, so it does involve a catalyst, do we have to know the name of the catalyst like the one involved in the dehydration of ethanol ?

Metal catalysts are used, but I doubt we need to know that.
Palladium and nickel, apparently* are the most commonly used.

Reply 14

Marcusroye98

Last years six markers : Titrations, Identifying Ions

Possible ones : Haber Process, Soaps, Making Salts, Ethanol production :smile:

Reply 15

NishalT

What comes under making salts?

Reply 16

LeEastafrican

Original post by NishalT

What comes under making salts?

i think its the topic about making salts using an insoluble base and soluble base linking into titration

Reply 17

NishalT

Yeah, that's it, hope that doesn't come up

Posted from TSR Mobile

Reply 18

Thomith

Could there be a 6 marker like they did on some assessment material where you were given 2 countries (one poor with no crude oil, one rich with alot of crude oil) and you were asked to evaluate the things they should consider when considering ethanol production (whether they should use fermenting glucose with yeast or the hydration reaction of ethene with steam to ethanol)

Soaps wouldn't be a bad 6 marker for me, I assume they would want you to say stuff about the soap being made from an ester and alkali (possible the breakdown of fat into glycerol then carboxylic acid then the alkali and the acid reacting to from potassium/sodium salts (the soap)) Then how the soap anion actually works to remove stains.
making salts wouldn't be that bad, I just need to remember you do a titration first when you have the bad/acid soluble solutions.
Not sure if i would know what specifically they would want about the Haber Process, i assume they would ask about why they use the specific environment they do (200atm to shift equilibrium towards the production of Ammonia, 450 Degrees to speed up the reaction even though it shifts the equilibrium the wrong way as a compromise, and the iron catalyst is just to speed things up without moving the equilibrium position.

I am worried as i am before every exam, i did 5 hours of revision yesturday and 6 and a half today and am planning to do 3 before the exam tommurrow, so hopefully i will be ready. I'm just worried about forgetting the equations and how moles work.

Also - do we need to know about trans fats (made by catalytic hydrogenation but have spare double bonds and how they are artificial and so can possibly cause things such as heart disease?)

(edited 9 years ago)

Reply 19

Shadowninja107

In the haber process, when the rate of the forward reaction is increased by lowering the temperature or increasing pressure for instance, surely the reaction comes out of equilibrium, does anyone understand beyond what is written in the textbook?