Official AQA AS Chemistry Unit 1 - 23Rd May 2013

I think I'm gonna kill myself, it clashes with my 2hr spanish exam so basically I'm not leaving that exam hall. And wait for the cherry on top, I have double chemistry last lessons. UGH.

You dont have study leave???

Reply 261

Bixel

5

Original post by SharminaSyeda

I think I'm gonna kill myself, it clashes with my 2hr spanish exam so basically I'm not leaving that exam hall. And wait for the cherry on top, I have double chemistry last lessons. UGH.

Take a break and don't attend the last chemistry lessons! Make sure your teacher knows you've had enough, though! :smile:

Reply 262

username984585

20

Original post by Bixel

Like this!

Aha! I see. Very helpful! Thanks a lot. :smile:

Reply 263

SharminaSyeda

Original post by Nav_Mallhi

You dont have study leave???

No :/ Sad times :frown:

Reply 264

loknath

7

Any predictions? :smile:

Reply 265

tumblrgirl

so i was doing this question and it was going fine, i found the moles of Bcl3 and then the moles of HCl then to find the concentration you do moles/vol but I don't understand why you multiply by 1000 like it says in the mark scheme :frown:

can someone help me please? :frown:

Reply 266

username984585

20

Original post by SharminaSyeda

No :/ Sad times :frown:

That is just crazy!
My study leave started on the 10th May and ends on the 10th June. :smile:

Reply 267

annaelizabet

6

does anyone know how to work out how many lone pairs F makes in HF hydrogen bonding?

Reply 268

A sheesh

13

Original post by tumblrgirl

so i was doing this question and it was going fine, i found the moles of Bcl3 and then the moles of HCl then to find the concentration you do moles/vol but I don't understand why you multiply by 1000 like it says in the mark scheme :frown:

can someone help me please? :frown:

Pits the same as doing 1.105/ 500/1000
they just do a different way, doing c=n/v is the same

Reply 269

Bixel

5

Original post by tumblrgirl

so i was doing this question and it was going fine, i found the moles of Bcl3 and then the moles of HCl then to find the concentration you do moles/vol but I don't understand why you multiply by 1000 like it says in the mark scheme :frown:

can someone help me please? :frown:

As the volume 500cm^3 is in cm^3, you can use the equation:
Number of moles = (concentration x volume) / 1000.

Rearranging this gives:
Concentration = (1000 x number of moles) / volume

Reply 270

pearson1995

Original post by Bixel

As the volume 500cm^3 is in cm^3, you can use the equation:
Number of moles = (concentration x volume) / 1000.

Rearranging this gives:
Concentration = (1000 x number of moles) / volume

Why do you times by 3??

Reply 271

ppginprg

4

Original post by annaelizabet

does anyone know how to work out how many lone pairs F makes in HF hydrogen bonding?

F has 7 electrons in the outer shell, one of these it shares with the H in a covelent bond so there are 6 left: 3 lone pairs, these are all able to form hydrogen bonds but each hydrogen only forms one hydrogen bond

Reply 272

tumblrgirl

Original post by Bixel

As the volume 500cm^3 is in cm^3, you can use the equation:
Number of moles = (concentration x volume) / 1000.

Rearranging this gives:
Concentration = (1000 x number of moles) / volume

Original post by A sheesh

Pits the same as doing 1.105/ 500/1000
they just do a different way, doing c=n/v is the same

lol i feel so silly not realising that, thanks for clearing that up :biggrin:

Reply 273

Aqib7

7

Original post by The Lawful T.J

I did it in January :P

How did you find it compared to the other papers?

Reply 274

annaelizabet

6

Original post by avb212

F has 7 electrons in the outer shell, one of these it shares with the H in a covelent bond so there are 6 left: 3 lone pairs, these are all able to form hydrogen bonds but each hydrogen only forms one hydrogen bond

thanks so much!! :biggrin:

what is the definition for hydrogen bonding??

Reply 275

mynameisntbobk

18

Has anybody asked anything on here that hasn't been answerd, can you ask it again please, it's quite difficult scrolling through the thread for questions which have or haven't been answered

Reply 276

Minz

There was this question in the jan 2012 paper as follows:

The boiling points of fluorine and hydrogen fluoride are –188 oC and 19.5 oC respectively.
Explain, in terms of bonding, why the boiling point of fluorine is very low.

I started to talk about bonding (molecular and ionic) instead of IMF as mark scheme states. I never know when to talk about bonding or IMF in these types of questions. :frown:

Any help?

Also, I've forgotten how to calculate the RAM in the spectrometry questions. Can anybody outline how you go about doing it from the data given in a table please.

(edited 10 years ago)

Reply 277

maryamnc

2

Original post by Nav_Mallhi

That is just crazy!
My study leave started on the 10th May and ends on the 10th June. :smile:

Same, and doing all my exams in june as well (other than c1 for maths which i did in jan) too stressful!

Reply 278

omnom

Original post by pearson1995

Why do you times by 3??

because there are 3 moles of the hcl, the moles you worked out was 1mol as there was only one bcl3 whereas the was 3HCL.

does that help?

Reply 279

maryamnc

2

Original post by mynameisntbobk

Has anybody asked anything on here that hasn't been answerd, can you ask it again please, it's quite difficult scrolling through the thread for questions which have or haven't been answered

I have a question that I'm pretty sure I asked earlier. How do you draw the structure for metallic and ionic bonding, can someone draw it out for me please :smile:

))

Official AQA AS Chemistry Unit 1 - 23Rd May 2013

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