Edexcel Chemistry A2 Unit 5 ~ Wednesday 19th June 2013 (Now Closed)

Can someone help me with the following questions and clear up any doubt please? ive given an answer and my reasoning behind it, i could be wrong though..



For this question i got the answer as C, as number of moles does not affect the e cell value (read this in many books) also the e cell is the most positive (right) minus the most negative (left)



I got the answer to be C, As it is 2 negative species attacking eachother which is unlikely and the other 3 show the H- acting as things it says its good at.



For this one i got the answer to be C again, i chose zinc but realized since it did not have a incomplete D shell could not catalyze reactions



Answer = A
Because the oxygen group needs to come off by accepting the lone pair, while the nucleophile attacks the slightly positive carbon.



I chose D because the h20 has deprotonated the cation and for the charges to balance, the metal has to decrease by 1.



4 H2 molecules and the enthalpy change is just the benzene hydrogenation and the other 1 added together.

The type of reaction is an addition right?



Answer is B, Because the first one isnt optically active, and the 3rd and 4th both have an extra cooh and nh2 group, increasing the acidity/basity and making the ph less equal, so B would give a neutral soultion.

Thanks in advance

Nope! U can put anything as X Y and Z

Posted from TSR Mobile

Wow you have paper.

1) You're right
2) You're right as the reaction is electrophilic addition
3) I put B as Fe is the only transition metal and transition metals act as catalysts. I have no idea if this is right though.
4) I also put A which I think is right
5) D is correct
6) Yep I also got 4 H2 and enthalpy for benzene - 120
7) Yep, B is right

Could you post some of the other multiple choice questions if it isn't too much trouble

D is not correct, C is because the oxidation of the Metal cation is not affected only the OVERALL charge, C is basically saying 3+ is more acidic than 2+

x

Can someone help me with the following questions and clear up any doubt please?



For this question i got the answer as C, as number of moles does not affect the e cell value (read this in many books)



I got the answer to be C, As it is 2 negative species attacking eachother which is unlikely and the other 3 show the H- acting as things it says its good at.



For this one i got the answer to be C again, i chose zinc but realized since it did not have a incomplete D shell could not catalyze reactions



Answer = A
Because the oxygen group needs to come off by accepting the lone pair, while the nucleophile attacks the slightly positive carbon.



I chose D because the h20 has deprotonated the cation and for the charges to balance, the metal has to decrease by 1.



4 H2 molecules and the enthalpy change is just the benzene hydrogenation and the other 1 added together.

The type of reaction is an addition right?



Answer is B, Because the first one isnt optically active, and the 3rd and 4th both have an extra cooh and nh2 group, increasing the acidity/basity and making the ph less equal, so B would give a neutral soultion.

Thanks in advance

Well it gave you a ratio which was in relation to XYZ respectively so I think it did matter. You'd only lose one mark if you didn't though.

Was it XYZ 221?

Posted from TSR Mobile

heres my thoughts on your queries:

q20 i believe is d, and not c. c is hydrogenation with a nickel catalyst and hydrogen (reduction) d

Thanks, But in D its acting as a strong base accepting a H+ and in A, the aldehyde is being reduced, so i put C,

heres my thoughts on your queries:

q1 is c

q20 i believe is d, and not c. c is hydrogenation with a nickel catalyst and hydrogen (reduction) d

q4 is c

q18 is a


q6 is c) because a higher charge density on the metal ion polarises the water ligands to a greater extent, making the hydrogen bonded to the oxygen more delta possitve and more easily lost. the reaction they chose is actually showing why a complex ion is an acidic solution. the oxidation state on the metal ion hasnt changed in the reaction so c is wrong. b is wrong as the Ph would in fact be higher if a lower charge, and A is nonsense.

iii) what you said is correct so 4h2 and the two values added together

q 15 is B

Can someone help me with the following questions and clear up any doubt please? ive given an answer and my reasoning behind it, i could be wrong though..



For this question i got the answer as C, as number of moles does not affect the e cell value (read this in many books) also the e cell is the most positive (right) minus the most negative (left)



I got the answer to be C, As it is 2 negative species attacking eachother which is unlikely and the other 3 show the H- acting as things it says its good at.



For this one i got the answer to be C again, i chose zinc but realized since it did not have a incomplete D shell could not catalyze reactions



Answer = A
Because the oxygen group needs to come off by accepting the lone pair, while the nucleophile attacks the slightly positive carbon.



I chose D because the h20 has deprotonated the cation and for the charges to balance, the metal has to decrease by 1.



4 H2 molecules and the enthalpy change is just the benzene hydrogenation and the other 1 added together.

The type of reaction is an addition right?



Answer is B, Because the first one isnt optically active, and the 3rd and 4th both have an extra cooh and nh2 group, increasing the acidity/basity and making the ph less equal, so B would give a neutral soultion.

Thanks in advance

Cheers pal. Could you upload the one about forming a polyamide (from the mcq)?

Can someone help me with the following questions and clear up any doubt please? ive given an answer and my reasoning behind it, i could be wrong though..



For this question i got the answer as C, as number of moles does not affect the e cell value (read this in many books) also the e cell is the most positive (right) minus the most negative (left)



I got the answer to be C, As it is 2 negative species attacking eachother which is unlikely and the other 3 show the H- acting as things it says its good at.



For this one i got the answer to be C again, i chose zinc but realized since it did not have a incomplete D shell could not catalyze reactions



Answer = A
Because the oxygen group needs to come off by accepting the lone pair, while the nucleophile attacks the slightly positive carbon.



I chose D because the h20 has deprotonated the cation and for the charges to balance, the metal has to decrease by 1.



4 H2 molecules and the enthalpy change is just the benzene hydrogenation and the other 1 added together.

The type of reaction is an addition right?



Answer is B, Because the first one isnt optically active, and the 3rd and 4th both have an extra cooh and nh2 group, increasing the acidity/basity and making the ph less equal, so B would give a neutral soultion.

Thanks in advance

It was the ones with NH2 and COCl groups if I remember correctly.

Can someone help me with the following questions and clear up any doubt please? ive given an answer and my reasoning behind it, i could be wrong though..



For this question i got the answer as C, as number of moles does not affect the e cell value (read this in many books) also the e cell is the most positive (right) minus the most negative (left)



I got the answer to be C, As it is 2 negative species attacking eachother which is unlikely and the other 3 show the H- acting as things it says its good at.



For this one i got the answer to be C again, i chose zinc but realized since it did not have a incomplete D shell could not catalyze reactions



Answer = A
Because the oxygen group needs to come off by accepting the lone pair, while the nucleophile attacks the slightly positive carbon.



I chose D because the h20 has deprotonated the cation and for the charges to balance, the metal has to decrease by 1.



4 H2 molecules and the enthalpy change is just the benzene hydrogenation and the other 1 added together.

The type of reaction is an addition right?



Answer is B, Because the first one isnt optically active, and the 3rd and 4th both have an extra cooh and nh2 group, increasing the acidity/basity and making the ph less equal, so B would give a neutral soultion.

Thanks in advance

Cheers pal. Could you upload the one about forming a polyamide (from the mcq)?

Sorry about the camera quality but these are the only pages i can do at the moment, Ill try upload the rest later:

Sorry about the camera quality but these are the only pages i can do at the moment, Ill try upload the rest later: