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OCR B Salters - F335 Exam - 15 June 2011

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But how were you supposed to know the moles of what you were trying to find out as you don't know they are the same surely :s-smilie:

You were given the equation above, there were 2 moles of NaOH to the acid, so you just multiplied by 2! :biggrin:

Reply 581

brendan.

Original post by tom108

Kinda 'okay' paper. Few nasty questions. The calcualtion at the end i got 12kg :frown:

Last question was nice. Buffers was nice. There was one about ' why did the student think it was okay to use a volume under 17.5?' what you all put?

I said that it depends on the concentration of the acid and alkali used which determines the volume needed? :confused:

Reply 582

Boompw

Original post by RobG93

Got 19g for question 5d.
Got pH 4.1 then pH 7.2 for the two pH questions.
Got mass 112 for the first mass question.

got 1,1-dibromoethane for the NMR q.

.. I thought the paper was alright, there were some tricky elements to it, and some easy parts to it, overall I'd say it was similar to the previous papers, and I'd say that the grade boundaries would be similar, roughy 80/120 maybe 85/120 for an A.

I got all those! :smile:

, I hope they're right.

For the 2 step process I did reflux with NaOH to get an ethan-1,2-diol and the reflux with Acidified Dichromate (VI) to get the carboxylic acid

Is this right?

Reply 583

SmileyGurl13

Original post by RobG93

I got all those answers :biggrin:

but there's like 3 different answers for the mass one 1 is ours 1 is 12g and I think I saw 5 or 7 somewhere on here :s-smilie:

AHH

Reply 584

SmileyGurl13

Original post by Tetanus

You were given the equation above, there were 2 moles of NaOH to the acid, so you just multiplied by 2! :biggrin:

Whoa what question is this :s-smilie:

Reply 585

beckyxo

i got 19g for the last one too :s-smilie:

mega hated the oxidation/reduction question, way simple but got me so confused it went to -4 and -2 or just -4?? ahh :frown:

also that SF6 dot cross was sp annoying, took ages drawing it then realised id only drawn 5 F's so had to start again :frown:

also what did people put for the one asking about why would farmers argue using that herbicide is ok?

Reply 586

Conor 419

Did well until the last question, I ran out of time. So many marks gone...****.

What's the general consensus, low or high grade boundaries?

Reply 587

zahre

Original post by RobG93

Got 19g for question 5d.
Got pH 4.1 then pH 7.2 for the two pH questions.
Got mass 112 for the first mass question.
got 1,1-dibromoethane for the NMR q.

.. I thought the paper was alright, there were some tricky elements to it, and some easy parts to it, overall I'd say it was similar to the previous papers, and I'd say that the grade boundaries would be similar, roughy 80/120 maybe 85/120 for an A.

What question was this?

Reply 588

tom108

Original post by Boompw

I got all those! :smile:

, I hope they're right.

For the 2 step process I did reflux with NaOH to get an ethan-1,2-diol and the reflux with Acidified Dichromate (VI) to get the carboxylic acid

Is this right?

I did that, but i dont think its right :frown:

Reply 589

RobG93

Last question..above or below the original energy level?

Reply 590

Paolat

Original post by Tetanus

It was phenylamine. Because it specified that the compound could be made in 1 step..

Is phenylamine an organic compound

Reply 591

RobG93

Original post by zahre

What question was this?

Where you had to find the mass of Lithium.

Reply 592

brendan.

Original post by SmileyGurl13

Yeah that's what I did :biggrin:

I know someone has already asked it but it wasn't really answered what did you guys put for the ox and reduction qs I also put both sulphur as someone else did but this can't be right, can it :s-smilie:

http://www.chemguide.co.uk/inorganic/redox/oxidnstates.html
Near the bottom it says how one element can be oxidised and reduced in same reaction, so it's possible. :smile:

Reply 593

Tetanus

Original post by SmileyGurl13

Whoa what question is this :s-smilie:

When you had to calculate the mass of that acid stuff that went into the buffer solution, it gave you information on the titration between tha acid and NaOH and gave an equation for the neutralisation above.