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OCR Chemistry F322~ 4th June 2013~ AS Chemistry

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Reply 2220

Bow Tie

Original post by geekD96

oh lord now im scared...could you give example for electrophilic then? thanks so much

Only thing is, you have to remember what happens to some kinds of nucleophillic substiution reactions and their products for example adding concentrate ammonia (NH₃) to fluouromethane (CH₃F) makes CH₃NH₂ and hydrogen fluoride (HF). There are a couple of dodgy examples you need to know in nucleophillic substitution but they aren't that bad once you know them.
The one with this example is that the NH₃ isn't all added.

CH₃F + NH₃ -> CH₃NH₂ + HF

Reply 2221

Kits

Original post by geekD96

aww you will be fine think positive ... to be honest I prefer afternoon ones...after lunch lol in the mornings I feel tired and hungry and sick :frown:

Lol yeah I will be :biggrin:

I just don't like em cause usually I get tired lol. When its in the morning I'm alert and what not!

Thanks btw and good luck

Reply 2222

Freyaa

Original post by anonymousecheese

ok so its not my calculator...its me :confused:

And me-.- Ive tried everything and gave up! I don't understand how to get it!

Reply 2223

Lagukage4

Original post by IM_SCREWED

if from molecular to empirical is simplifying it, shouldn't it just be x ing it to get the molecular?

if you have worked out the empirical formula and they want the molecular formula, they will give you the Mr of the molecular formula... so just do:
Mr of molecular formula
Mr of empirical formula
the answer to this is what you multiply every atom in the empirical formula by, which gives the molecular :smile:

Reply 2224

anonymousecheese

Original post by Freyaa

I got the same I don't understand how to get the answer on the markscheme:/

does anyone know how to get the answers in these questions?

Reply 2225

Blashnet

Original post by simifeltham

It is indeed but so are electrophilic addition reactions.

you will only really come across homolytic fission in ozone depletion reactions or radical substitutions

omg! that cleared so much up!!! thanks :smile:

Reply 2226

Freyaa

Original post by geekD96

nucleophillic=heterophilic...and electrophilic=homo? is this right

No electrophilic addition is also heterolytic as one of the atoms has both of the electrons :wink:

Reply 2227

simifeltham

Original post by anonymousecheese

ok so its not my calculator...its me :confused:

n=m/mr so 1x10^6/64.1=15600 part ii
n=v/24 so 3.6x10^5/24 = 15000 part iii
15000/15600 x 100 = 96% part iv

Reply 2228

opengeek

Original post by Freyaa

And me-.- Ive tried everything and gave up! I don't understand how to get it!

is this some enthelpy question ?

Reply 2229

geekD96

Original post by Kits

Lol yeah I will be :biggrin:

I just don't like em cause usually I get tired lol. When its in the morning I'm alert and what not!

Thanks btw and good luck

oh yeah..you too :smile:

you prepared?

Reply 2230

Freyaa

Original post by simifeltham

n=m/mr so 1x10^6/64.1=15600 part ii
n=v/24 so 3.6x10^5/24 = 15000 part iii
15000/15600 x 100 = 96% part iv

Thankyou so much!! I was being a pleb (a)

Reply 2231

simifeltham

Original post by Freyaa

Thankyou so much!! I was being a pleb (a)

Your welcome

Reply 2232

Freyaa

Original post by opengeek

is this some enthelpy question ?

Yes 1 e iii) on June 2010 paper

Reply 2233

Ché.

Original post by Blashnet

omg thankyou!! :biggrin:

So any radical has undergone homolytic fission?

Radical Substitution is the ONLY mechanism or topic that involves homolytic fission.
Addition and other substitution reactions are totally heterolytic!

Posted from TSR Mobile

Reply 2234

geekD96

Original post by Freyaa

No electrophilic addition is also heterolytic as one of the atoms has both of the electrons :wink:

may I just ask...that there is a nucleophillic addition and a nucleophillic substituition...are those different or same ;/ I think im overcomplicating myself :frown:

Reply 2235

anonymousecheese

Original post by simifeltham

n=m/mr so 1x10^6/64.1=15600 part ii
n=v/24 so 3.6x10^5/24 = 15000 part iii
15000/15600 x 100 = 96% part iv

aah, thank you :smile:

for some reason i get a different answer when i do 1.00x10^6 :mad:

Reply 2236

opengeek

Original post by Freyaa

Yes 1 e iii) on June 2010 paper

I remember that question it made me so angry ...the mark scheme was definitely talking rubbish ! no matter what i did i couldn't get the answer :/

Reply 2237

Liberty.

I hope there is a question on explaining the effect of catalysts on the rate of reaction using enthalpy diagrams and the Boltzmann distribution...
I'm on this **** :colone:

Reply 2238

Freyaa

Original post by geekD96

may I just ask...that there is a nucleophillic addition and a nucleophillic substituition...are those different or same ;/ I think im overcomplicating myself :frown:

We weren't taught nucleophilic addition just nucleophilic substitution and electrophilic addition:/