Equilibria, Energetics and Elements (F325) - June 2011 Exam.

This paper was hard - but not impossible. Its going to define between the people who really know their chemistry and worked very hard to deserve an A star. The buffer question was hard - but then again if they were to give us any other buffer question it would have been far too easy. There was a question like this on one of the old OCR past papers.
Maybe theres point in complaining.. but probably not. I think it should be around 75% for an A, 85% for an A*.
I got some things wrong, I know I definitely lost about 10 marks - the erest will have just been minor errors.
And on the plus side - it was much easier than Biology F215 on Monday!

for the last question i just worked out the moles of that thingg and divided it by 2 (total guess) then got a percentage of like 13%... haha
omg i cant believe i am laughing my future depended on thiss exam it was horrible!!!!!!!!!!!!!!!!!!
i almost burst out crying in the exam i dont know what to do or say im so so so so guttted

what did u guys get for the complex ions?

when it was substitued by hcl was it ni(cl)4?

Guys lets make the Unofficial Mark Scheme Mk1
Please say if you have things to add, modify, or correct (theres lots!)

?)definition of lattice enthalpy: Energy given out when one mole of an ionic compound is formed from its constituent gaseous ions.[2]
?)Why is hydration enthalpy for Cl- exothermic? Bonds formed with deltaH+ on water molecules, heat given out.
?)Born Haber diagram of Enthalpy of solution, hydration, lattice enthalpy. 4 stages, incomplete answers: Mg2+(g) + 2Cl-(aq), Mg2+(aq) + 2Cl-(aq) [2]
?)
?
?)
?)
?)Magic tang question: use lactic acid because its pKa is close to our desired pH (within one unit), so it buffers better. I used henderson hasselbach equation, pKa = pH + log [A-]/[HA] or you can use the ka expression to work out [A-]/[HA], which (I got) ~0.49
I think it will be tangy because the buffering range (+/- 1 pH unit of pKa) certainly ecompasses the tangy pH of 3.55

Did anybody get a KC value of 45?? I deem this one of the easier questions but still, they managed to make ever the simplest of topics within the unit tricky. I can understand you make some things hard and some easier, but literally everything in the paper required more than the average time to think about it. If you have to read so much b****x about 'sweets' and fictitious material then the time allocated should increase. It seems the time taken to read each question has significantly increased, meaning less time to solve them... Does that make sense or am I the only one who believes so??

Did anybody get a KC value of 45?? I deem this one of the easier questions but still, they managed to make ever the simplest of topics within the unit tricky. I can understand you make some things hard and some easier, but literally everything in the paper required more than the average time to think about it. If you have to read so much b****x about 'sweets' and fictitious material then the time allocated should increase. It seems the time taken to read each question has significantly increased, meaning less time to solve them... Does that make sense or am I the only one who believes so??

I'm in the same boat as you. I dont think i've even got an Eand i tried so hard in revision but my mind went blank in the exam.

I think I've failed... I can't face my family and tell them. I really don't know what to do same

w.

If they want to show an constant half life why not do it PROPERLY instead of doing averages!!!? goshh! so annoying....because most people would think that would be a second order no?

Im supposed to get an A in this and the smartest girl in our class had no clue what was going on in that paper!!!!

what did you guys think of the grade boundary ?

noooo! dont say that! its right its definitely probably right!

I's sorry but i worked EXTREMELY hard. Is going through the spec 4 times not enough? Reading every page of the unit at least 5 times not enough? I really sat my ass down this year to get into uni and thanks to OCR im not going to anymore.

how big is your ego?

I got 33.8% but I think that's wrong

I put order 1 just because it was only a line of best fit, many points were not on the line

Wow what a ridiculous exam, perhaps the hardest Ive ever had to battle through.

I need 87 UMS marks to get onto my Chem eng Degree. How many proper marks will this be?