Chemistry c2 unit 2 aqa monday gcse 20th new spec

What would be the points for a 6-mark insoluble salt making question?

1) Mix ionic substances in solution
2) Filter/wash/dry precipitate to obtain salt.

Is there anything else??

Also what kind of things would they look for in a 6-mark electrolysis question?

What would be the points for a 6-mark insoluble salt making question?

1) Mix ionic substances in solution
2) Filter/wash/dry precipitate to obtain salt.

Is there anything else??

Also what kind of things would they look for in a 6-mark electrolysis question?

Last year had a 6 marker on making salts. They wanted you to describe the steps you would take in an experiment to create a salt. E.g using universal indicator, stirring and bunsen burners

Careful! That question was on soluble salts and not insoluble salts. Very Big difference in terms of production, if you cant remember i suggest you go back and revise...

Last year had a 6 marker on making salts. They wanted you to describe the steps you would take in an experiment to create a salt. E.g using universal indicator, stirring and bunsen burners

Sort of points you could get in for soluble salt:

An Insoluble salt will not dissolve in solution, so the salt is formed as a precipitate. To Achieve Salt X (they'll name a salt in the question) you'll need to mix solution Y and Z together (names dependant on the salt you're trying to make). To obtain the precipitate you use a filter. The salt should then be washed with distilled water to remove the other soluble product. Finally, the salt can be dried in an oven.

That could be enough for six marks.

Points for electrolysis:

Question, describe the electrolysis of Brine and how its products can be used.

Brine is made up of sodium chloride and water. Chlorine moves towards the anode where is gives up an electron to form chlorine gas- insert relevant half equation. Chlorine gas can be used in the production of bleaches and plastics.

Hydrogen moves towards the cathode where it gains an electron to form hydrogen gas- insert relevant half equation. Hydrogen forms at the cathode rather than sodium as it is lower in the reactivity series (this is to do with electrode potential, essentially hydrogen is lower down in the reactivity series so it will be reduced and gain electrons rather than something higher up), Hydrogen gas can be used in Hydrogen fuel cells and in modified combustion engines.

A solution of Sodium Hydroxide is left, which is a useful component in making chemicals like soaps.

Hope this helps

You're right I need to brush up on how to make in/soluble salts. For some reason, I just can't seem to memorise it.. I'm fine with everything else though.

Thanks alot! Please correct me if I'm wrong but for electrolysis of brine, the half equations are:

At negative electrode:
2H⁺ + 2e- --> H₂

At positive electrode
2Cl^- --> Cl₂ + 2e^-

The remaining OH^- and Na⁺ ions which do not form at any electrode bond to form NaOH.

Perfect! So the hydroxide doesn't form at the electrode because it doesn't fit through the porous membrane, and the Sodium doesn't form at the cathode as it is higher up in the reactivity series than hydrogen (If you can understand that concept then you're well on your way to A level!).

Edit: one other point that could be worth remembering is that if the sodium and hydroxide is still in solution they don't officially bond together as such, in solution they just remain as ions

They're really not gonna ask a question on nano particles as the six mark question. Theres hardly enough detail in the text book for 5 solid separate points. It will come up in the paper almost certainly, but i doubt as the six marker.

Maybe I have been unintentionally biased towards myself but I got 54/60 first time round on the June 2012 paper, I find C2 relatively easy compared to C3 just learning alot of content rather than challenging stuff like titration

It's managable just alot harder than say percentage yields from C2!

Does anyone know how to make salts from insoluble bases? And I mean the experiment....

Step 1: add insoluble base to acid. Warm gently on a tripod and gauze (do not boil).
Step 2: the solution changes colour as reaction occurs, showing the products forms. Excess products can be seen.
Step 3: when the reaction is complete, filter the solution to remove excess products.
Step 4: evaporate the water so that the salts start to form. Stop heating when you see the first salts appear at the edge of the solution. Then leave the rest of the water to evaporate slowly.
I hope this is what you were looking for!