Edexcel - Chemistry Unit 2 - 4 June 2013

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Reply 860

Priya08

can anyone explain what instantaneous-induced dipole is ? and an example im getting so confused

Reply 861

Tuya

Original post by Gunner121

Can anyone please tell what do we have to know about carbon nanotubes ?

Uses like caging drugs
Properties like high strength and conductivity

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Reply 862

Priya08

Original post by Tuya

Uses like caging drugs
Properties like high strength and conductivity

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is carbon nanotubes and buckminister fullerene the same thing

Reply 863

Tuya

Original post by Priya08

can anyone explain what instantaneous-induced dipole is ? and an example im getting so confused

It's a tad late to learn about those now, coz half the paper might be based on those. They are also called London forces.
The theory is that in a molecule, electrons are likely to be on one side of the molecule. So that side is slightly negatively charged and the other end is slightly positively charged. This is an instantaneous dipole. Because of these, the electrons in other molecules of the substance are repelled or attracted ie an induced dipole. Overall, these are attractive forces which is why non polar molecules don't just scatter away.

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Reply 864

Tuya

Original post by Priya08

is carbon nanotubes and buckminister fullerene the same thing

Kind of. The nanotubes and buck minister belong to a class of carbon molecules called fullerenes. The buck minister fullerene is specifically a C60 molecule in the shape of a sphere. Nano tubes are also fullerenes except they're tube shaped.

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Reply 865

johnny-marr

Original post by Priya08

can anyone explain what instantaneous-induced dipole is ? and an example im getting so confused

Same as London forces/Van der Waals...called many different things. They are found between every molecule, the weakest intermolecular force and are caused by the uneven distribution of electrons which create this instantaneous dipole in a molecule.

So like in a Cl---Cl bond one of the chlorines will be slightly positive the other will be slightly negative, if alligned to an adjacent Cl---Cl then an attraction will occur between the two dipoles.

Reply 866

marseille_h

Little question : 1-iodobutane can me made by reacting butan-1-ol with phosphorus(III) idodie, PI3, formed by reacting moist red phosphorus with iodine.

Complete the equation for the formation of 1-iodobutane.

PI3 + ...C4h9OH -) ?

I looked at the answer in the mark scheme but don't understand :colondollar:

Reply 867

posthumus

Original post by marseille_h

little question : 1-iodobutane can me made by reacting butan-1-ol with phosphorus(iii) idodie, pi3, formed by reacting moist red phosphorus with iodine.

Complete the equation for the formation of 1-iodobutane.

Pi3 + ...c4h9oh -) ?

I looked at the answer in the mark scheme but don't understand :colondollar:

pi3 + 3 c4h9oh ----> 3ch2h5i + h3po3

EDIT: Why on earth does it end up going lower-case

(edited 10 years ago)

Reply 868

Tuya

Original post by marseille_h

Just remember this... ImageUploadedByStudent Room1370276126.215431.jpg

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Reply 869

maryam1996

Hi, is there a way to know if a reaction is nucleophilic or electrophilic, or do we just have to remember it for each reaction and does anyone have an easy way of remembering it?? Thank you!

Reply 870

marseille_h

Original post by Tuya

Just remember this... ImageUploadedByStudent Room1370276126.215431.jpg

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Thanks , i went through the revision guide for 2days learning every single thing but it dosen't come up in my mind when doing past papers. :frown:

Reply 871

Khurc003

Anyone know how to calculate this?? The ans is D but not sure how...?

The enthalpy change of neutralization of an acid by an alkali is measured by adding
10.0 cm3 of hydrochloric acid to 10.0 cm3 of sodium hydroxide. 10.0 cm3 pipettes with
an accuracy of ±0.04 cm3 are used to measure out both solutions.
The overall percentage error in measuring the total volume of the reaction mixture is

A ±0.04%
B ±0.08%
C ±0.4%
D ±4.0%

Reply 872

kevsamuel

Why's Chemistry so hard? fml.

Reply 873

Big-Daddy

Original post by maryam1996

Hi, is there a way to know if a reaction is nucleophilic or electrophilic, or do we just have to remember it for each reaction and does anyone have an easy way of remembering it?? Thank you!

In general it's not so easy to tell whether an electrophile was involved first or a nucleophile, you have to be able to see the mechanism in your head when you look at the reactants/products or reactants/catalysts. But for AS level I think the only time it is electrophilic is when it is addition onto a C=C double bond. And if it is addition then it will be electrophilic, if it is substitution of any atom other than H it will be nucleophilic (common nucleophiles are -OH, X-, -C triple bond N, -NH2, etc.), if it is substitution of H it will be free radical substitution.

Reply 874

bhowland1994

Original post by marseille_h

PI3 + 3 C4h9OH - 3C4H9I + H3PO3

Reply 875

SophieL1996

http://www.edexcel.com/migrationdocuments/QP%20GCE%20Curriculum%202000/june2010-qp/6CH02_01_que_20100607.pdf q19 iv why do you times it by 10 ?? thanks you :smile:

Reply 876

Big-Daddy

Original post by Khurc003

I seem to remember from doing this past paper that the answer is actually C? Though I can't explain why. I got 0.8% and then decided that 0.4% is closest so wrote that one down. (0.04/10.0)*2=0.8%.

Reply 877

Masturchess

Original post by Big-Daddy

I seem to remember from doing this past paper that the answer is actually C? Though I can't explain why. I got 0.8% and then decided that 0.4% is closest so wrote that one down. (0.04/10.0)*2=0.8%.