AQA A2 CHEM4 & CHEM5 June 2015 [official discussion thread]

Guys I wanted to ask if I can draw mechanisms in pencil? I prefer pencil because its neater and i can show bonds clearly, but will AQA accept it? Thanks in advance.

Posted from TSR Mobile

If its a Hb pencil or something that will show up on the scanners yes (basically the same pencils use in maths to draw graphs)
I would recommend doing it in pen to be safe though

I would but i always make the bonds rough in pen. I use a Staedtler pencil and it says HB on it?

Posted from TSR Mobile

draw it in pencil, and go over it in pen?

I would but i always make the bonds rough in pen. I use a Staedtler pencil and it says HB on it?

Posted from TSR Mobile

If its a Hb pencil or something that will show up on the scanners yes (basically the same pencils use in maths to draw graphs)
I would recommend doing it in pen to be safe though

I always draw mechanisms in pencil, then just to be safe I write a note in pen, saying I drew it in pencil.

Hmmm... I'll have to see then. Another question if you don't mind. In electrochemical cells, is every metal rod coated in platinum?

Posted from TSR Mobile

its my understanding platinum electrodes only come into use when one electrochemical cell contains no substances in the solid state i.e hydrogen reference electrode, and hence platinum is used as it can conduct electricity and is inert.

Ok so if it has no metal, then it has platinum. But if it has no metal, what does platinum cover? And in which case does platinum coat a metal?

Posted from TSR Mobile

Ok so if it has no metal, then it has platinum. But if it has no metal, what does platinum cover?

Posted from TSR Mobile

how do you work out moles at equilibrium when they give you moles of reactants before equilibrium and 1 products mole at equilibrium e.g. Jan10 chem 4 1a

They tell you the equilibrium mixture contained 0.54 of Ethyl propanoate.

We can use this info to calculate the moles of both products and reactants.

Considering its a 1:1 ration this is relatively straight forward.

So they tell you that Propanoic acid has 1.00 Mol. In equilibrium it will be (1-0.54) = 0.46.

Ethanol 2.00 Mol, at equilibrium its (2-0.54) = 1.46

For H2O they have given you 5.00 Mol so in equilibrium it would be (5+0.54) = 5.54


Just remember you always take away on the left hand side and add to whatever is on the right handside.

They tell you the equilibrium mixture contained 0.54 of Ethyl propanoate.

We can use this info to calculate the moles of both products and reactants.

Considering its a 1:1 ration this is relatively straight forward.

So they tell you that Propanoic acid has 1.00 Mol. In equilibrium it will be (1-0.54) = 0.46.

Ethanol 2.00 Mol, at equilibrium its (2-0.54) = 1.46

For H2O they have given you 5.00 Mol so in equilibrium it would be (5+0.54) = 5.54


Just remember you always take away on the left hand side and add to whatever is on the right handside.

A sample of 0.220 mol dm–3 solution of ethanoic acid was titrated against sodiumhydroxide solution.

(i) Calculate the volume of a 0.150 mol dm–3 solution of sodium hydroxide requiredto neutralise 25.0 cm3 of the ethanoic acid solution.

I got 0.327cm3, but that seems really wrong to me...

Where's this from and do you have the answer?