-
We need your support!
We are currently struggling to cover the operational costs of Xtremepapers, as a result we might have to shut this website down. Please donate if we have helped you and help make a difference in other students' lives!
Click here to Donate Now (View Announcement)
Search results
-
Chemistry: Post your doubts here!
Hi, please include the answers to make it easier for us to reply. I've covered this paper in the youtube video, you can take a look at it, if the explanations aren't too clear after viewing, feel free to clarify over here. -
Chemistry: Post your doubts here!
Hi, please include the answers to make it easier for us to reply. w03qp1 Q3. C6H12 + 9O2 --> 6CO2 + 6H2O moles of H2O : moles of CO2 6:6 mass of H2O absorbed : mass of CO2 absorbed 6 x 18: 6 x 44 0.41:1 Q27. Butanol has the following structural isomers 2-Butanol has a chiral carbon, so it... -
YouTube Videos on Past Year Chemistry MCQs
Video on Nov 2011 P11 uploaded http://www.youtube.com/playlist?list=PL4Jmce8VJnNX-EKGH10S1O8HEK2elI72j This is likely to be the final paper uploaded before your exams. I will try to work on the rest of the papers (both A and O levels) for the next few months and upload them eventually. But I... -
Chemistry: Post your doubts here!
Video on Nov 2011 P11 uploaded http://www.youtube.com/playlist?list=PL4Jmce8VJnNX-EKGH10S1O8HEK2elI72j This is likely to be the final paper uploaded before your exams. I will try to work on the rest of the papers (both A and O levels) for the next few months and upload them eventually. But I... -
If given only heat of combustions, then use heat of combustion of reactants - heat of formation...
If given only heat of combustions, then use heat of combustion of reactants - heat of formation of products If given only heat of formation, then use heat of formation of products - heat of formation of reactants If given only bond energy, BE of reactants - BE of products- Metanoia
- Profile post comment
-
Chemistry: Post your doubts here!
s08qp1 Q4. BaO2 anion is two oxygen atoms with a total of -2 charge, hard to type out......(O2)2- We have one single bond among the two atoms and 1 extra electron to each atom. Q8. If you link it to y = 1/x , you should remember its a curve, with the axis as asymptotes. Q22. The carbons are... -
Chemistry: Post your doubts here!
Q5. Fix P4O10 as 1 mole P4O10 + 6CaO + --> 2Ca3(PO4)2 Q6. Just use proportion if its easier to visualise. mass of N in 100 g of fertiliser = 15 g mass of N in 14 g of fertiliser = (15/100) x 14= 2.1 g moles of N in 14 g of fertiliser = 2.1 /14 = 0.15 mol conc of N in 5 dm^3 of solution =... -
Chemistry: Post your doubts here!
Moles = conc x volume you did it as moles = conc/volume ? -
Chemistry: Post your doubts here!
s08qp1 Q6. Answered in post 9750 just above. H2O(s) --> H2O(g) Moles of H2O = mass of ice/Mr of H2O = 1/18= 0.0556 PV/nT (ideal gas) = PV/nT (H2O) (1)(24)/(1)(298) = (1)V/(0.0556)(596) Q15. CaCo3 --> CaO + CO2 mass of CaCO3 = 1200 million tonnes work out moles of CaCO3 then moles of CO2... -
Chemistry: Post your doubts here!
w07qp1 Qn 9 : moles of SO3 2- : moles of electrons : moles of metal 0.0025 : ? : 0. 005 1 :? : 2 1 : 2 : 2 2 mol of metal gained 2 mol of electrons 1 mol of metal gained 1 mol of electron (oxidation state will thus decrease by 1) Original oxidation state of metal = +3 Final oxidation state =... -
Chemistry: Post your doubts here!
Are you able to post your working? -
Chemistry: Post your doubts here!
s08qp1 Just use proportion if its easier to visualise. mass of N in 100 g of fertiliser = 15 g mass of N in 14 g of fertiliser = (15/100) x 14= 2.1 g moles of N in 14 g of fertiliser = 2.1 /14 = 0.15 mol conc of N in 5 dm^3 of solution = 0.15/5 = 0.03 mol/dm^3 -
Chemistry: Post your doubts here!
Ca(s) --> Ca(g)--> Ca+ (g) --> Ca2+ (g) --> Ca2+ (aq) add up the energy changes involved in the stages, with 1st and 2nd IE from the data booklet. -
Chemistry: Post your doubts here!
hmmm, it was actually answered a page ago. s08qp1 Q6. H2O(s) --> H2O(g) Moles of H2O = mass of ice/Mr of H2O = 1/18= 0.0556 PV/nT (ideal gas) = PV/nT (H2O) (1)(24)/(1)(298) = (1)V/(0.0556)(596) V = 2.67 dm^3 -
Chemistry: Post your doubts here!
for a saturated molecule: CnH2n+2 -
Chemistry: Post your doubts here!
I don't have the data booklet, but perhaps can try adding up 1st and 2nd IE of Al. Then see which of the options 1st IE + 2nd IE gives the same value. -
Chemistry: Post your doubts here!
w09qp12 Q40. Requires a bit of reasoning, if 1 mole of monomer join together, we will get less than 1 mole of polymer. If we end up with 1 mole of polymer in the end, it means none of the monomer has joined to any other! Its like 1000 bricks (monomer) will build one house (polymer) , the... -
Chemistry: Post your doubts here!
w09qp12 Q12. SiCl4 + 2H2O --> SiO2 + 4HCl (acidic) Q2o. IF all carbons are single bonds, CnH2n+2O, C20H42O (20 carbons , 42 hydrogen, 1 oxygen) Since 1 aldehyde group is present, subtract 2 H, C20H40O (20 carbons , 40 hydrogen, 1 oxygen) Since it contains a ring, subtract another 2H... -
Chemistry: Post your doubts here!
s08qp1 Q6. H2O(s) --> H2O(g) Moles of H2O = mass of ice/Mr of H2O = 1/18= 0.0556 PV/nT (ideal gas) = PV/nT (H2O) (1)(24)/(1)(298) = (1)V/(0.0556)(596) V = 2.67 dm^3 Q26. Increase in the 2 oxygen means that the 2 OH has been oxidized to 2 COOH groups. The two OH must be primary alcohols... -
Chemistry: Post your doubts here!
Please include the answers so its easier to reply with our suggestions. s11qp12 Q11. Some students have suggested using Al3+ and "crossing it" with C4- to get Al4C3 The "crossing of charges method" does give us the correct answer in this case, so if all else fails, I guess we can use it...