OCR B Salters - F335 Exam - 15 June 2011

I worked out the ration to be 0.63 or something? Sound familiar?

Ratio of what?

The last quesion with the 4 marker calculation

SF6 was one and LiF I think!
I put covalent for SF6 and ionic for the other.

I was so confused be the conjugate acid question!!! Damn it ! Now I know the answer it seems so obvious!!

Omg why don't I remember this question :/
Ahhhhhh

Thats wrong i think sorry. :/

3SF2 + 02 ---> 2SF6 + SO2

FML FML FML *goes to revise for biology unit 5 and Chemistry f334

lol were in the same boat. bio unit 5 is going to be a killer

I think he's talking about the mass one

Just wondering what people got for the Stotal and Ssystem? I got like +9k(roughly) and -268 for system. Messed up this paper big style.

Oh no, I think I got this wrong...

You mean the one about how much was dissolved to make the buffer?

I think this is what I did. It was pH 7, so I worked out the concentration of H+ needed, then substituted that into the equation for Ka, and found what the ratio of the other two was. Then substituted in the concentration that we were given to find the concentration of the other one. Then converted that concentration into g dm-3 and got something like 19 g?

Thinking back I don't think that was right, but it completely made sense at the time haha.


Some really nasty questions on that paper, but some nice ones too I'm now going to unsubscribe to this thread so I don't realise any others I've got wrong and start panicking haha.

edexcel better behave for unit5.. monday was a joke -___-

Same. I thought I'd fluffed it up. They tried to confuse us by putting the - in front of the DeltaH value.

Overall. I was displeased by the emphasis on bonds and electronegativity, when there could have been more questions on azo dye synthesis etc, but, I'd revise just enough to get through it so... Hopefully it'll be okay!

I worked out the ration to be 0.63 or something? Sound familiar?

So I've dropped roughly 15-20 marks... Ouch