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very urgent a level chem question
Once the radicals have formed, they are highly reactive. Give the equations for two propagation steps that occur in the reaction of ethane with chlorine.
For this question, i got the reactions right but the mark scheme says this:
DO NOT ALLOW dots on molecules
Why is that? I drew the correct reactions but lost two marks because i put dots on the radicals
I have my exam tomorrow so I would really appreciate if someone could respond quickly
For this question, i got the reactions right but the mark scheme says this:
DO NOT ALLOW dots on molecules
Why is that? I drew the correct reactions but lost two marks because i put dots on the radicals
I have my exam tomorrow so I would really appreciate if someone could respond quickly
Reply 1
Original post
by lifeofpablo1Once the radicals have formed, they are highly reactive. Give the equations for two propagation steps that occur in the reaction of ethane with chlorine.
For this question, i got the reactions right but the mark scheme says this:
DO NOT ALLOW dots on molecules
Why is that? I drew the correct reactions but lost two marks because i put dots on the radicals
I have my exam tomorrow so I would really appreciate if someone could respond quickly
For this question, i got the reactions right but the mark scheme says this:
DO NOT ALLOW dots on molecules
Why is that? I drew the correct reactions but lost two marks because i put dots on the radicals
I have my exam tomorrow so I would really appreciate if someone could respond quickly
You can only put "dots" on radicals. If you put a "dot" on a molecule it must have gained an electron.
Cl2 ==> 2Cl•
Cl• + C2H6 ==> C2H5• + HCl
C2H5• + Cl2 ==> C2H5Cl + Cl•
etc.
Reply 2
molecule refers to cl2 for example. cannot put a dot there
Reply 3
14
okay thank you both
Reply 4
14
Original post
by charcoYou can only put "dots" on radicals. If you put a "dot" on a molecule it must have gained an electron.
Cl2 ==> 2Cl•
Cl• + C2H6 ==> C2H5• + HCl
C2H5• + Cl2 ==> C2H5Cl + Cl•
etc.
Cl2 ==> 2Cl•
Cl• + C2H6 ==> C2H5• + HCl
C2H5• + Cl2 ==> C2H5Cl + Cl•
etc.
wait i wrote the second equation and the third exactly as you just wrote them, but in the mark scheme it said do not allow dots on molecules. heres the question and mark scheme if you want to take a look
Reply 5
Original post
by lifeofpablo1wait i wrote the second equation and the third exactly as you just wrote them, but in the mark scheme it said do not allow dots on molecules. heres the question and mark scheme if you want to take a look
My interpretation of this marks scheme is that you don't need to include the single electron on the radicals BUT you will be marked incorrect if you place a dot on a molecule.
So, the equations I wrote are correct, and the versions that do not show the unpaired electron will also be marked correct, BUT molecules that are not free radicals will be marked incorrect if an unpaired electron is shown.
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