Chemistry OCR AS F321 Atoms, Bonds and Groups May 2012

Original post by Natalie21

Correct

although for formation of ozone i'd put it as O2 + O goes to O3 (with reversible eq arrow)

Your turn :smile:

What do you understand by the term Nucleophile and in which mechnaism is this occur?

Reply 381

Original post by scorpio22

finally finshed homework.i can join in :biggrin:

good

was my answers correct ?

Reply 382

Original post by otrivine

good

was my answers correct ?

you were

Reply 383

OP

Original post by otrivine

What do you understand by the term Nucleophile and in which mechnaism is this occur?

An atom or molecule that contains an electron pair that it can donate to form a covalent bond.

Nucleophilic substitution (e.g. the hydrolysis of halogenoalkanes).

Next question:

How can you track the differences in rate of reaction between halogenoalkanes containing iodine and bromine, and what observations you would expect to see.

Reply 384

Original post by otrivine

What do you understand by the term Nucleophile and in which mechnaism is this occur?

it is an electron pair donor e.g : o-h

it is used in nucleophillic substitution

ch3ch2cl + oh---->ch3ch2oh + cl-

Reply 385

Original post by Natalie21

An atom or molecule that contains an electron pair that it can donate to form a covalent bond.

Nucleophilic substitution (e.g. the hydrolysis of halogenoalkanes).

Next question:

How can you track the differences in rate of reaction between halogenoalkanes containing iodine and bromine, and what observations you would expect to see.

Iodine has a faster reaction with less than than Br as it has a weaker bond enthalphy requring less energy to overcome.
im not sure about the observation.would it be that br is cream and I is yellow?

Reply 386

Original post by Natalie21

An atom or molecule that contains an electron pair that it can donate to form a covalent bond.

Nucleophilic substitution (e.g. the hydrolysis of halogenoalkanes).

Next question:

How can you track the differences in rate of reaction between halogenoalkanes containing iodine and bromine, and what observations you would expect to see.

you can use AGNO3 to iodine and bromine which for iodine it forms a yellow ppt and bromine cream ppt and C-I bond is the weakest as less energy is needed to break the bond and therefore has the fastest rate of reaction.

Reply 387

Original post by scorpio22

it is an electron pair donor e.g : o-h

it is used in nucleophillic substitution

ch3ch2cl + oh---->ch3ch2oh + cl-

correct well done :wink:

my turn

Reply 388

Original post by otrivine

correct well done :wink:

my turn

name and explain 3 process into petrochemical.give examples if needed

Reply 389

Original post by scorpio22

name and explain 3 process into petrochemical.give examples if needed

sorry have not revised this part in which chapter is this?

Reply 390

Original post by otrivine

sorry have not revised this part in which chapter is this?

pg 120-121
its catalytic cracking

branching/isomerism

cyclic

Reply 391

OP

Original post by scorpio22

Iodine has a faster reaction with less than than Br as it has a weaker bond enthalphy requring less energy to overcome.
im not sure about the observation.would it be that br is cream and I is yellow?

See otrivine's answer :smile:

Original post by otrivine

you can use AGNO3 to iodine and bromine which for iodine it forms a yellow ppt and bromine cream ppt and C-I bond is the weakest as less energy is needed to break the bond and therefore has the fastest rate of reaction.

Yeah exactly and the yellow ppt would appear more quickly than the cream ppt would.

Original post by scorpio22

name and explain 3 process into petrochemical.give examples if needed

Never heard of this?

Reply 392

Original post by Natalie21

See otrivine's answer :smile:

Yeah exactly and the yellow ppt would appear more quickly than the cream ppt would.

Never heard of this?

yes me too i got worried i didnt hear of this from the book as well

Reply 393

OP

Original post by otrivine

yes me too i got worried i didnt hear of this from the book as well

I know those equations but never heard of that generic name for them :/

Reply 394

Original post by scorpio22

pg 120-121
its catalytic cracking

branching/isomerism

cyclic

next question please mate 2 more

Reply 395

Some questions for you guys :smile:

Sorry if they are worded awfully, rushed :/
These questions are more to do with understanding and so many of these might not be in the spec :smile:

Spoiler

(edited 12 years ago)

Reply 396

Original post by scorpio22

name and explain 3 process into petrochemical.give examples if needed

EDIT: my spelling and sentence structure is awful lol
Fractional distillation: crude oil made of many different lengths of hydrocarbons and is pumped into a fractionating column and separated into different fractions that have similar lengths and boiling points.

Catalytic cracking: longer chained alkanes make insufficient fuels as they tend to suffer from incomplete combustion and they are also produced from fractional distillation, so they are passed over a zeolite catalyst and cracke down into smaller chained alkanes (used as fuel) and alkenes (used as feedstock)

Isomerisation: branched chains have lower boiling points than straight chains and so are added to fuel to help it burn more effciently, straight chains from crude oil are converted into branched chain alkanes by isomerisation

Reforming: to form cyclics hydrogen is by product

(edited 12 years ago)

Reply 397

OP

Woah thank you for posting all these questions! I've spoilered my answers so others can answer too! Thank you :biggrin:

Spoiler

Reply 398

Original post by Natalie21

Woah thank you for posting all these questions! I've spoilered my answers so others can answer too! Thank you :biggrin:

Spoiler

All correct just add few pointers :smile:

Stuff about thermodynamics is to help in terms of understanding why reactions occur in exo- or endo- direction, hope this helps :smile:

Spoiler

STABILITY ISN'T IN THE SPECIFICATION WAS USING MY TEACHERS NOTES TO MAKE THE QUESTIONS, JUST A WAY FOR UNDERSTANDING THE 2ND PART OF THE UNIT, SORRY

(edited 12 years ago)

Reply 399