AS Chemistry- helping each other out!

http://filestore.aqa.org.uk/subjects/AQA-CHEM1-QP-JAN13.PDF

Can someone help me with question 4g. Thanks :smile:

Reply 1162

http://filestore.aqa.org.uk/subjects/AQA-CHEM1-QP-JAN13.PDF

Original post by Super199

Can someone help me with question 4g. Thanks :smile:

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Don't be put off by the structure.
First the question hints it's an isomer of an alkane.
Remember the general formula for alkanes is CNH2N+2,there are five carbons so you plug five in and you get the molecular formula C5H12. Remember, the number of carbons determine how you name it,so five carbons means it's pentane.
The structure is pentane.

Reply 1163

Super199

Original post by Kadak

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Don't be put off by the structure.
First the question hints it's an isomer of an alkane.
Remember the general formula for alkanes is CNH2N+2,there are five carbons so you plug five in and you get the molecular formula C5H12. Remember, the number of carbons determine how you name it,so five carbons means it's pentane.
The structure is pentane.

Yeah sorry I got that bit. Is the next one something to do with the surface area and the number of van der waals being less? Care to explain that question.

Reply 1164

Original post by Super199

Yeah sorry I got that bit. Is the next one something to do with the surface area and the number of van der waals being less? Care to explain that question.

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Yes,since the isomer is branched,it has less surface contact area(or you can call it points of contact) than the straight chained isomer,so less Van der Waal forces are formed.

Since the branched isomer has less Van der Waal forces,it take less energy to overcome the Van der Waal forces so it's boiling point is lower.
Hope that helps 😃.

Reply 1165

jontypickles

2

Want to get involved in this tread. Taking OCR as chemistry :smile:

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Reply 1166

S.Ahmad

10

Original post by Super199

Yeah sorry I got that bit. Is the next one something to do with the surface area and the number of van der waals being less? Care to explain that question.

Branched alkanes have fewer points of contact between molecules this leads to fewer van der Waals' forces between the molecules. Also, the molecules can't get as close to each other and so this decreases the intermolecular forces between the molecules.

Reply 1167

mismash

2

can any one post any useful resources or notes they have for OCR saltars B chemistry.
thank you v much... :smile:

Reply 1168

Original post by S.Ahmad

Branched alkanes have fewer points of contact between molecules this leads to fewer van der Waals' forces between the molecules. Also, the molecules can't get as close to each other and so this decreases the intermolecular forces between the molecules.

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Anyone have any good revision material for Mass spectroscopy and infrared spectroscopy?

Reply 1169

User1686961

12

Original post by Kadak

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Anyone have any good revision material for Mass spectroscopy and infrared spectroscopy?

I have some stuff from last year but i'm not sure how to upload it because its hand written.

Reply 1170

BBeyond

15

I hate these drawing questions :frown:

http://gyazo.com/347ea8636b70bd8cd64df98ea70316c6 What do I draw??

Reply 1171

S.Ahmad

10

Original post by Kadak

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Anyone have any good revision material for Mass spectroscopy and infrared spectroscopy?

I have handwritten notes which I'll upload shortly.

Original post by BBeyond

I hate these drawing questions :frown:

http://gyazo.com/347ea8636b70bd8cd64df98ea70316c6 What do I draw??

Okay, first of all you need to recognise the type of reaction: this is the formation of a salt as implied by the H+ reacting with a metal: Acid + Metal -> Salt + H2. Whenever it mentions collecting gas you want to draw a displacement of water apparatus (conical flask with acid, with a bung attached to the delivery tube which is connected to an upright graduated cylinder full of water which is in a water bowl, or similar apparatus but instead the delivery tube is connected to a gas syringe.

Apparatus 1) The water displaced is the volume of Hydrogen gas produced.
Apparatus 2) Read off the gas syringe.

(edited 9 years ago)

Reply 1172

abdullahharis

2

Original post by BBeyond

I hate these drawing questions :frown:

http://gyazo.com/347ea8636b70bd8cd64df98ea70316c6 What do I draw??

u r right, they r hard nd confusingly complicated.

Reply 1173

LadyEcliptic

I did CCEA chemistry to A level, so I'm here to help ^^

Reply 1174

yung7up

3

Easter holidays coming up currently doing aqa as chem, wanna make a timetable to stick to, any suggestions for how i should do it + any general revision tips

Thanks

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Reply 1175

Original post by yung7up

Easter holidays coming up currently doing aqa as chem, wanna make a timetable to stick to, any suggestions for how i should do it + any general revision tips

Thanks

Posted from TSR Mobile

Posted from TSR Mobile
Make a timetable and stick to it. Do plenty of past papers and get into good exam habits.
For example,say you got a question on ionisation energies across the period.
First you will highlight the command word,and see the number of marks.This will give you an idea how to answer the question.
You would write out beside the questions the keywords atomic radius,number of protons, nuclear attraction and electron shielding. As you answer the question you will tick off the words to make sure you havent left any of the key factors out.

Reply 1176

yung7up

3

Original post by Kadak

Posted from TSR Mobile
Make a timetable and stick to it. Do plenty of past papers and get into good exam habits.
For example,say you got a question on ionisation energies across the period.
First you will highlight the command word,and see the number of marks.This will give you an idea how to answer the question.
You would write out beside the questions the keywords atomic radius,number of protons, nuclear attraction and electron shielding. As you answer the question you will tick off the words to make sure you havent left any of the key factors out.

Yh thats exactly what im doing except mentally lol im fairly confident with unit 1 so ill be focusing on unit 2 mainly but thank you very much :smile:

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Reply 1177

Super199