[QUOTE=RIPme;65990633]hahhaha just the whole thing in general

right okay haha i'll try to break up some of the main things you should know! Haber Process; nitrogen and hydrogen mixed in a ratio of 1:3 to form ammonia. You must know that they are reacted at 450C, pressure of 200 atmospheres and with an iron catalyst. Im sure you know the formula and that it is a reversible reaction. It is a reversible reaction as some of the ammonia which is formed can then break down to nitrogen and hydrogen again. Em also only around 10% of nitrogen and hydrogen are converted to ammonia and the unreacted N and H are recycled. The gases are also cooled to condense the ammonia. Then you must be aware of why the process has the requirement i mentioned above eg 450C etc.. A lower temperature would mean more ammonia however you must remember a lower temperature will slow down reaction time as the iron cataylst wont work at a lower temperature so know that 450C is a COMPROMISED temperature. Also be aware haber process cant be performed in a school lab because high pressures and temperature can be too dangerous for students and too expensive for schools.

Reply 1065

username2618375

[QUOTE=gabrielealek;65991089]right okay haha i'll try to break up some of the main things you should know! Haber Process; nitrogen and hydrogen mixed in a ratio of 1:3 to form ammonia. You must know that they are reacted at 450C, pressure of 200 atmospheres and with an iron catalyst. Im sure you know the formula and that it is a reversible reaction. It is a reversible reaction as some of the ammonia which is formed can then break down to nitrogen and hydrogen again. Em also only around 10% of nitrogen and hydrogen are converted to ammonia and the unreacted N and H are recycled. The gases are also cooled to condense the ammonia. Then you must be aware of why the process has the requirement i mentioned above eg 450C etc.. A lower temperature would mean more ammonia however you must remember a lower temperature will slow down reaction time as the iron cataylst wont work at a lower temperature so know that 450C is a COMPROMISED temperature. Also be aware haber process cant be performed in a school lab because high pressures and temperature can be too dangerous for students and too expensive for schools.
oh and a higher pressure would mean a higher yield of ammonia but again you need to consider the costs of high pressures and safety precautions

Reply 1066

username2618375

[QUOTE=RIPme;65990633]hahhaha just the whole thing in general
okay now contact process - dont over complicate it just remember the four stages. 1. sulfur burned in air to form sulfur dioxide; combustion of sulfur and the equation S + O(2) = SO(2)

2. the requirements (catalytic production of sulfur TRIOXIDE) so the sulfur dioxide produced in stage 1 is reacted with more air, temp of 450C, pressure of 2 atmospheres and a cataylst vanadium(V) oxide. So now with all these the sulfur dioxide is converted to sulfur trioxide and it is a reversible reaction again like the haber process a lower temp would mean more sulfur trioxide but cataylst wont work so lower rate of reaction. 2SO(2) + O(2) = 2SO(3)

3. absorption in concentrated sulfuric acid so the sulfur trioxide is DISSOLVED in concentrated sulfuric acid to form OLEUM H(2)S(2)O(7) the reaction for this is SO(3) + H(2)SO(4) = H(2)S(2)O(7)

4. the dilution of oleum so the oleum is mixed with water to produce CONCENTRATED SULFURIC ACID and the equation is H(2)S(2)O(7) + H(2)O = 2H(2)SO(4) Remember that sulfur trioxide is not mixed directly with water because that reaction would be too exothermic and will produce a corrosive mist

Reply 1067

jackcoys

any predictions for chemistry? i'm revising materials right now and it's the most boring thing ive ever done in my life

Reply 1068

username2618375

[QUOTE=jackcoys;65992985]any predictions for chemistry? i'm revising materials right now and it's the most boring thing ive ever done in my life double award sulfuric acid came up and ion exchange + removing hard water by boiling so maybe something similar?

Reply 1069

Vickyahunter

Original post by jackcoys

any predictions for chemistry? i'm revising materials right now and it's the most boring thing ive ever done in my life

From doing past papers I've noticed that things from materials haven't shown up in a while. Eg. Electrolysis and the extraction of Al from its ore. I just hope that Al extraction doesn't come up because I have nothing to say about it! Fingers crossed it's a 6 marker on the blast furnace!

Reply 1070

jackcoys

Does anyone revise the actual experiments from Quantitative chemistry? Like finding the average titre experiments? Don't know if I should bother and just revise how to prepare a pipette/burette

Reply 1071

GoNinty

further maths people, how's your revision going? i am dreading this exam and every second of revision is more and more painful. i blasted through most of mechanics last night and im just going over friction and moments right now. going to start on statistics, which i absolutely loathe. seriously, i hate statistics. i hated it in normal maths and in further maths i hate it even more.

even after going through mechanics questions on past papers it still doesn't feel like i know anything. ugh. i want to be doing pure maths again haha.

hopefully this exam is forgiving. it's my last exam and I am 100% ready to be done. it's fair to say these 4 weeks have been the most stressful time of my life so far.

Reply 1072

Vickyahunter

Original post by GoNinty

I despise paper 2 altogether. The only word to describe statistics is UGH. Pure is 100% the better paper. I still have chem tomorrow, fm on Thurs and Physics on Friday and I am so ready to be done with everything. It's got to the stage where all my friends are off enjoying life and I'm stuck doing revision that I can't be bothered to do (hence I'm here!) Anyway, good luck for Thursday. Lets hope and pray it is easier than what it seems!

Reply 1073

wizardry9

Original post by Vickyahunter

I so agree with both of you!! Statistics is just horrible. Further Maths 2 is actually killing my soul right now, I keep doing questions but it just seems its always a bit hit or miss if I actually do it right! I've got Chem and German tomorrow, FM on Thurs and then my final exam is Physics on Friday so it's so hard to find stay motivated, especially because paper 2 FM and Physics suck so much!! Good luck!!

(edited 7 years ago)

Reply 1074

brendan730

Does anyone know what TA science raw grade boundaries are like?

Reply 1075

Vickyahunter

Original post by wizardry9

I can't do Physics 2 at all! I hate waves and light and I am so much better with all the equations. See all this electricity mumbo jumbo, I can't see it so I can't understand it! I think its the same for mechanics in FM... Why do I need to find the coefficient of friction of a rough horizontal plane?!?!

Reply 1076

GoNinty

Original post by Vickyahunter

i feel the exact same. my best friend, who finished his last exam on monday, is enjoying taunting me about all of his free time he now has :P

three exams in three days? ouch. good luck for tomorrow and the following two days, hope everything goes well.

the end is in sight!

Reply 1077

jackcoys

Chemistry went well. I think I have got a good shot of getting a mid A in it though, I know where I have lost marks.

In the "which reaction is which" I had no idea for the neutralisation. I think I ended up with BCDE as my answers. On the last question I definitely dropped 2 or 3 marks, when it asked me to find the moles of the 25cm3 solution I got the ratio of 2:1, divided the original moles by 2 and then multiplied it by 25/1000 and got 0.063 or something. Pretty disappointed with that last page. I didn't get to balance 2 equations either.

But i'm not going to fret over 5 or 6 marks when it's out of 115. 100 could secure myself an A* but I have a tenancy to make silly mistakes so I reckon i'll end up with an A/high B.

(edited 7 years ago)

Reply 1078

RJM1802

Original post by jackcoys

Im the same for the reactions i just guessed BCCD, and i messed up the whole page of functional groups and formulas. I didnt balance 2 equations as well. I think ive lost around 15 marks although im so happy bc i started revising at 9pm last night! I think ive managed an A overall, although loads of people in my year found it very difficult, so the grade boundaries might be low... For the last moles question did people get 160 for rfm and n=3? Empirical formula= C3H5