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Chemistry: Post your doubts here!
I've attached the electron in boxes configuration for C and N. C has and empty p orbital but N does not, so statement 1 is incorrect. The last occupied shell is 2 for both C and N, so statement 2 is correct. -
Hi everyone
Ah... i see the button now. Will play around it, makes answering the mcqs so much easier.. Thanks!- Metanoia
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- Forum: Welcome Lounge
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Chemistry: Post your doubts here!
Is your confusion on the statement 3 for nitrogen? Using NH4+ as example, we can see that a N atom can actually form 4 covalent bonds (where 1 of them is a dative bond). So it makes statement 3 of the question true. -
Hi everyone
Hi all, I was looking for online practice papers for my students when I came across this great forum. So now hanging around and trying to help out a bit for those posting questions on chemistry. I would like if there is a way to directly attach diagrams from my hard drive, or I have to upload...- Metanoia
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- Replies: 4
- Forum: Welcome Lounge
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Chemistry: Post your doubts here!
An autocatylsed reaction is when one of the products is actually a catalyst. The rate of reaction : starts off slow (no catalyst) then increases (catalyst) then decreases (concentration of reactants decreases) In general, to estimate the "Mr of a gas mixture containing A and B", we use (% of... -
Chemistry: Post your doubts here!
w11qp11 Q9. I usually try to create the eqm table Ag+ .........+ ......... Fe2+.........--> .........Ag.........+ Fe3+ 1...............................1...............................-..............0.... initial conc -0.56........................-0.56... -
Chemistry: Post your doubts here!
Q30. A: (Correct) PVC gives off toxic gases when burnt, among them are HCl which is the acid gas. B: (Correct) C=C bonds forms C-C bonds C: (Correct) Empirical formular of both PVC and monomer are the same (addition polymer) C2H3Cl D: (Wrong) Repeating unit is C2H3Cl -
Chemistry: Post your doubts here!
s12qp11 Q6. Its a matter of using a gas constant of your choice and then converting the rest of the variables to the correct units. For me, I usually use R = 8.31 , so pressure has to be expressed in Pa, volume in m3, temperature in K n = 0.56/Mr of ethene = 0.56/28 = 0.02 V= nRT/p = 0.02 x... -
Chemistry: Post your doubts here!
Hi, to make it easier for us to check, could you also put the marking scheme answers next to the 5 questions? -
Chemistry: Post your doubts here!
Try to draw the lewis structure of CN- :C:::N: 1 lone pair on C 3 bonding pairs between C and N 1 lone pair on N -
Chemistry: Post your doubts here!
Ok, I spotted my mistake, it was ok till one part. Energy given out in forming bonds of C16H34 and 2 C12H24 34 (C-H) and 15 (C-C) bonds and 2 (C=C) and 20 (C-C bonds) and 48 (C-H) = 34 (410) + 15 (350) + 2 (610) + 20 (350) + 48(410) =47090 kJ (instead of 46680 kJ in my first attempt) Enthalpy... -
Chemistry: Post your doubts here!
Q4. Use any of the alkane as an example and construct a balance equation for complete combustion, for here, I'll use CH4 I prefer to use table, but not sure if the alignment shows when typed out. CH4 (g) + 2O2 (g) --> CO2 (g) + 2H2O (l) 10 .............70 ................0 ... -
Chemistry: Post your doubts here!
Is this the actual question? We'll need to make some reasonable assumptions here that the C12H24 is an alkene rather than a cycloalkane. The C12H24 would be having one C=C bond as it is "missing" 2 hydrogen Energy taken in to break bonds of C40H82 82 (C-H) and 39 (C-C) bonds = 82 (410) + 39... -
Chemistry: Post your doubts here!
No problem, I'm actually a tutor based in Singapore, so I guess we are neighbors. Would like to get an understanding of students exams schedule in other countries, so in Malaysia, both the A and O levels (?) are done in May and not November? -
Chemistry: Post your doubts here!
Notice that the H on the centre Carbon is ultimately replaced by CN? This would require us to change the H with a halogen (either Br or Cl), one way to do it would be free radical substitution. Then the halogen alkane intermediate will undergo a nucleophilic substitution by adding CN- (using... -
Chemistry: Post your doubts here!
W: reacts with Br2 and uv to form intermediate CH3CHBrCH3 , which then reacts with CN- X: reacts with Br2 and uv to form intermediate (CH3)2C(OH)Br ,which then reacts with CN- Y: reacts with HBr to form intermediate CH3CHBrCH3 , which then reacts with aq. NaOH Z: undergoes hydrolysis to form... -
Chemistry: Post your doubts here!
Heat of neutralization for strong acids and strong alkali is estimated to be -57kJ PER MOLE of H2O formed. For both experiments. (Involving strong acid and bases) , it reflects twos moles of water formed . So heat of reaction is -57 x 2 for both equations.