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Chemistry: Post your doubts here!
w11q13 Check post #9228 on pg 462 It is likely that you wrongly included Ag (s) into the Kc expression? If so, remember we don't include solids in the Kc. -
Chemistry: Post your doubts here!
W06qp1 Just take 10cm3 of CH4 as example and form a balance eqn CH4 + 2O2 --> CO2 + 2H2O We will use up 20 cm3 of O2 and produce 10 cm3 of CO2. So 50 cm3 of unused O2 and 10 cm3 of CO2 gives us total of 60cm3 of gas for CH4. So its graph D if we look at CH4. -
Chemistry: Post your doubts here!
S11Q12 In this case, the cross multiplication does give us the answer, but have to be careful at A levels, not all species need to satisfy the octet rule. E.g AlCl3 and SO4 2- This was what i suggest some posts ago Understand that whatever moles of C we have at the beginning will eventually... -
YouTube Videos on Past Year Chemistry MCQs
user name is meta tutor. I'm sorry, but I'm not too sure how get around the problem that youtube is not allowed to be viewed on your side. I'm currently working on Oct 2013 and 2009. Not based on any request by students, but just starting with the more recent ones and working backwards on... -
YouTube Videos on Past Year Chemistry MCQs
http://www.youtube.com/playlist?list=PL4Jmce8VJnNXSmX2z10ACyurQ7mWgY0fq Video of June 2011 is uploaded. -
Chemistry: Post your doubts here!
http://www.youtube.com/playlist?list=PL4Jmce8VJnNXSmX2z10ACyurQ7mWgY0fq Video of June 2011 is uploaded. -
YouTube Videos on Past Year Chemistry MCQs
I'm not sure if its your intention to make me less willing to carry on the project. But you are close to succeeding. -
Chemistry: Post your doubts here!
Q9. Yes. H2O form in all, but different moles. -
Chemistry: Post your doubts here!
Q12. Unfortunately, I feel its a poorly set question, as the scale is hard to compare. I feel peak of C is too high. Q9. What I suggest is just a guide line, don't forget we need to factor in energy given out when H-O-H bonds are formed on the other side. Q18. It is a paper that is set some... -
Chemistry: Post your doubts here!
w11qp12 mass of ethanol converted to ethanal = 0.7 x 2.3 = 1.61 g moles of ethanol converted to ethanal = 1.61/ 46 =0.035 moles of ethanal = 0.035 mol mass of ethanal = 0.035 x 44 = 1.54 g -
Chemistry: Post your doubts here!
Statement 1 true Mg + Cl2 --> MgCl2 Na + 1/2Cl2 --> NaCl Statement 2 true H2 + Cl2 --> 2HCl KBr + 1/2Cl2 --> KCl + 1/2Br2 Statement 3: Not true, might not be in syllabus anymore? NaOH (cold) + 1/2Cl2 --> 1/2NaCl + 1/2NaClO + 1/2H2O NaOH (hot) + 1/2Cl2 --> 5/6NaCl + 1/6NaClO3 + 1/2H2O -
Chemistry: Post your doubts here!
Q11. The Cr is +6 before and after reaction. Q12. Quite true, its was puzzling to me, the peak if shifted so far right would be really really low. So I prefer the other option. Its debatable. Q18. That option is under transition metals, I believe is not required in your syllabus. -
Chemistry: Post your doubts here!
W05qp1 Q17. This question comes from the chapter of transition metals, I'm not sure its relevant to your syllabus now. Q18. ammonium salt + base --> salt + water + NH3 ammonium sulfate + calcium hydroxide --> calcium sulfate + H2O + NH3 Nutrient of nitrogen in the fertilzer is lost as NH3 gas... -
Chemistry: Post your doubts here!
W04qp1 Q5. You have to imagine yourself filling up the boxes with 8 electrons. If you follow the rules, you will end up with a final configuration that has the lowest energy level. Q9. The short answer is, compared other organic compounds with the same number of carbons, burning a hydrocarbon... -
Chemistry: Post your doubts here!
s12qp11 Q2. Removing products shift the equilibrium to the right, but does not increase the forward rate of reaction. Please see post #9494 for a sketch explanation. Q3. Equation can represent both Heat of formation of water : H2 (g) + 1/2 O2 (g) --> H2O (l) , exothermic or heat of combustion... -
YouTube Videos on Past Year Chemistry MCQs
Its a bit tough, cause I'm getting messages from students in this forum to help with questions. And also I have to give time to my own students. :confused: -
YouTube Videos on Past Year Chemistry MCQs
Ok, I'll try to speed up. My idea was that students need to only watch the parts on questions which they have difficulty with, not the whole video, so I was trying to be more detailed in the explanations. -
Chemistry: Post your doubts here!
S07qp1 Hi, please try to type the answers next to the questions so we can reply much faster. :) Q11. The 2nd experiment has more moles of products but slower initial speed. This can happen when we add a diluted solution to the original concentration 1) the number of moles of H2O2 increases... -
Chemistry: Post your doubts here!
s12qp11 Q19. If wondering why not ans A, in the examiners approach, they don't view CO--> CO2 as spontaneous. Q22. Products formed CH3CH2OH, CH3CH2COONa % of CH3CH2OH = Mr of CH3CH2OH/(Mr of CH3CH2O- + Mr of CH3CH2COONa) x 100% = 46/(46+96) x 100% = 32.3% Q27. C-I bond is weakest, so I-...