i swear the OCR guys this year must've been high when they wrote their papers. Hedgehogs and seaweed eating sheep in biology and now we've got willy wonka in chemistry with his magic tangy sweets. what next eh. :P
the velocity of a falling OCR examioner from a cliff, i hope im be the one who'll be doing the pushing
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] ?) ?) graph question. Marks for calculating 3 half lives, ~200s, stating that constant half life means its 1st order. State that methanoic acid in excess, so [methanoic] is constant and can be disregarded in the rate equation. calculate k, answer and units= ?? s^-1 ?) ?) ?) ?) ?)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 ?) ?) ?)H2 uses. The question asked for large scale usage, only two that immediately come to mind are H2 in hydrogenation of veg oils to produce margarine, and Haber process. ?) ?) ?)monomer unit for the complex ion polymer EDIT: JtKing3000 tells that they asked for the 4,4 version, not the 2,2 i've put up. He's right. ?)
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?) % of Cu in Brass question Equations with state symbols: Cu (s) + 4HNO3 (l) --> Cu(NO3)2 (aq) + 2NO3- (aq) + 2NO + 2H2O Cu2+ + 2I- (aq) --> CuI (s) + 0.5 I2 (aq) 2HNO3 (aq) + Na2CO3 (aq) --> 2NaNO3 (aq) + H2O (l) + CO2 (g) (one more which i can't rememebr) n(Cu) = 0.5n(I2) = n(S2O3) titre of 24.98 x 10^-3 cm^3 or summin, 0.1moldm^-3, n (S2O3)=that, so n(Cu) = 24.98 x 10^-3 cm^3 so m(Cu) = nM = 24.98 x 10^-3 * 63.5 = 1.59 g of Cu in 2.8g or summin brass. % by mass= 67 point something percent, it asked to 1dp.
I was kinda worried about the exam because I hadn't really done much revision, but it surprisingly wasn't that difficult. The topics were all ones that I remembered being taught, and the rest, I worked out intuitively - and some logical thought.
Overall, I'd say not bad. Expecting 80%-90%.
Also, this is science guys. It's not merely an exam. The questions weren't that difficult if you had been trained to think critically - though, that would not entirely be the fault of you, as most curriculums focus more on solving repititive sets of problems rather then thinking critically and applying what you know to more complex phenomena and context.
I completley agree. And what makes me think this even more is, my friends who resat the AS June unit this year.... said that exam was as easy as anything?! So are they going to try and give the AS's a false sense of security and think they are awesome at the subject so they will go to uni and pay too much?? The exams will go dead easy next year you watch. i dont get it.
The exams are written years in advance, this had probably been written before the election had even happened!
I completley agree. And what makes me think this even more is, my friends who resat the AS June unit this year.... said that exam was as easy as anything?! So are they going to try and give the AS's a false sense of security and think they are awesome at the subject so they will go to uni and pay too much?? The exams will go dead easy next year you watch. i dont get it.
As aqa, ocr etc only do a-level qualifications it makes no sense for them to have easier or harder exams because they wont get any more money from student fees. Also, UMS will sort out any discrepancies derived from the difference in paper difficulty....
I put something along the lines of "they may be able to emulate the sourness, but not the sweetness of that magic tang." One of the most bizarre questions I've seen.