AS Chemistry- helping each other out!
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hi, merry christmas and seasons greetings to you all! 
i was wondering if someone could help me get my head around the concept of solubility in chemistry for each of ionic, covalent, and metallic bonding. i understand the gcse elements of it i.e. whether each one is soluble or not but can't seem to grasp the reasons why at a-level standards.
so i know the general rule ''like dissolves like'' meaning if something needs to be soluble in water, it needs to form hydrogen bonding with the molecule/compound that is dissolving as otherwise it would favour bonding with itself. for example, hydrocarbons cannot dissolve as they van der waals and this is not polar therefore will not dissolve.
in another case, ethanol has a hydroxyl (OH) making part of the molecule polar and therefore soluble. however, if the chain of an alcohol increases the proportion of the whole molecule to the small polar (OH) area on the molecule is not that significant thus does not dissolve.
for ionic bonding, the ions are polar and can be separated and ion-solvent bonds if it is with water. so for example, with MgO hydrogen bonding forms between the oxygen in MgO and the slightly delta positive hydrogen, making it soluble. but what about NaCl? ok, i get it is soluble, wonderful but although it is polar and forms ions the forces of attraction formed with the water molecules will be dipole dipole forces rather than hydrogen bonding - which is odd because i always thought that water would rather bond with itself in this case as it favours hydrogen bonding. i read somewhere that this is because the forces of attraction between NaCl and water molecules is greater than the electrostatic forces of attraction between ions. since when were hydrogen bonds stronger than electrostatic forces?
also, why don't metals dissolve? i know that the metal ions dont have poles but i just don't understand
i think i've confused myself and everyone haha, but any help would be appreciated!
i was wondering if someone could help me get my head around the concept of solubility in chemistry for each of ionic, covalent, and metallic bonding. i understand the gcse elements of it i.e. whether each one is soluble or not but can't seem to grasp the reasons why at a-level standards.
so i know the general rule ''like dissolves like'' meaning if something needs to be soluble in water, it needs to form hydrogen bonding with the molecule/compound that is dissolving as otherwise it would favour bonding with itself. for example, hydrocarbons cannot dissolve as they van der waals and this is not polar therefore will not dissolve.
in another case, ethanol has a hydroxyl (OH) making part of the molecule polar and therefore soluble. however, if the chain of an alcohol increases the proportion of the whole molecule to the small polar (OH) area on the molecule is not that significant thus does not dissolve.
for ionic bonding, the ions are polar and can be separated and ion-solvent bonds if it is with water. so for example, with MgO hydrogen bonding forms between the oxygen in MgO and the slightly delta positive hydrogen, making it soluble. but what about NaCl? ok, i get it is soluble, wonderful but although it is polar and forms ions the forces of attraction formed with the water molecules will be dipole dipole forces rather than hydrogen bonding - which is odd because i always thought that water would rather bond with itself in this case as it favours hydrogen bonding. i read somewhere that this is because the forces of attraction between NaCl and water molecules is greater than the electrostatic forces of attraction between ions. since when were hydrogen bonds stronger than electrostatic forces?
also, why don't metals dissolve? i know that the metal ions dont have poles but i just don't understand
i think i've confused myself and everyone haha, but any help would be appreciated!
Original post by zhang-liao
Besides Calorimetry, not much. I just hate Calorimetry so much..
student measured the enthalpy change of combustion C5H4O2 using calorimetry
He measured the mass of c5h4O2 and change in temp.
To work out enthalpy change of combustion what else does the student need to know [ 3 marks]
Original post by lyricalvibe
student measured the enthalpy change of combustion C5H4O2 using calorimetry
He measured the mass of c5h4O2 and change in temp.
To work out enthalpy change of combustion what else does the student need to know [ 3 marks]
He measured the mass of c5h4O2 and change in temp.
To work out enthalpy change of combustion what else does the student need to know [ 3 marks]
The student needs to know the mass of C3H402 before burning and after burning, he must also know the mass of solution, the specific heat capacity of the solution and the number of moles of C5H4O2 used?
Spoiler
Original post by zhang-liao
The student needs to know the mass of C3H402 before burning and after burning, he must also know the mass of solution, the specific heat capacity of the solution and the number of moles of C5H4O2 used?
Spoiler
When I said he knows the mass of the oxygenate I meant he knows the mass before and after already(this counts as one fact anyway ie change in mass).
Which solution?if you're talking about the oxygenate solution you're given he already knows this and it can't be part of your answer
Which solution?if you mean water(theoneheated from burning) you're correct but wouldn't get the mark for lack of specificity
Number of moles is correct but too general, something specific related to moles is needed
Ocr b Brah, always have always will
:spoiler:well until uni 
:spoiler:(edited 9 years ago)
Original post by lyricalvibe
When I said he knows the mass of the oxygenate I meant he knows the mass before and after already(this counts as one fact anyway ie change in mass).
Which solution?if you're talking about the oxygenate solution you're given he already knows this and it can't be part of your answer
Which solution?if you mean water(theoneheated from burning) you're correct but wouldn't get the mark for lack of specificity
Number of moles is correct but too general, something specific related to moles is needed
Which solution?if you're talking about the oxygenate solution you're given he already knows this and it can't be part of your answer
Which solution?if you mean water(theoneheated from burning) you're correct but wouldn't get the mark for lack of specificity
Number of moles is correct but too general, something specific related to moles is needed
But Edexcel don't really ask those questions though?
Aren't you doing AQA?
My problem seems to be not being specific enough or reading the question well enough though...
Original post by zhang-liao
But Edexcel don't really ask those questions though?
Aren't you doing AQA?
My problem seems to be not being specific enough or reading the question well enough though...
Aren't you doing AQA?
My problem seems to be not being specific enough or reading the question well enough though...
Ocr b
most questions are straight recall and th really not harder than gcse on our unit 1 exam-just different content.That can daily be worked n, just try and put answers down as you saw in the textbook, I normally try and visualise the page
Have any of you guys got mocks coming up?
If yes then how do you revise?
What do you use?
How long have you revised for?
I'm doing AQA btw.
If yes then how do you revise?
What do you use?
How long have you revised for?
I'm doing AQA btw.
Original post by lyricalvibe
Chemistry is great! Follows on from gcse well so I'd advise trying for an A* in it at gcse just so you knkw you're in a good possition- but that's deffinately not necessary
Advantages... Well it's respected and is needed/useful for most/all STEM subjects.
Rearange equations, that's about it so far, i doubt they'll have us resolving forces/using trig any time soon
Advantages... Well it's respected and is needed/useful for most/all STEM subjects.
Rearange equations, that's about it so far, i doubt they'll have us resolving forces/using trig any time soon
Thanks and thanks to all that replied
I'm sure in core science gcse I can get an A* and in additional science I can get an A or A * if I revise lol Just gonna have to wait and seeOriginal post by Dhanny
Have any of you guys got mocks coming up?
If yes then how do you revise?
What do you use?
How long have you revised for?
I'm doing AQA btw.
If yes then how do you revise?
What do you use?
How long have you revised for?
I'm doing AQA btw.
Yep, I think most of us have mocks coming up in January
I revise using past papers and tackling questions right now though before the holidays I was making notes
I revise on and off so sometimes I procrastinate loads and other times I'll revise loads
Honestly speaking, I need to revise my other subjects though, haven't done enough for them...
Original post by lyricalvibe
Ocr b most questions are straight recall and th really not harder than gcse on our unit 1 exam-just different content.
That can daily be worked n, just try and put answers down as you saw in the textbook, I normally try and visualise the page
most questions are straight recall and th really not harder than gcse on our unit 1 exam-just different content.That can daily be worked n, just try and put answers down as you saw in the textbook, I normally try and visualise the page
Did a past paper and got 80% though most of the questions I've done already in class and lessons though...
- I think UMS wise, that's a good A I believe 64/80 (the A benchmark is 48/80 for that paper)I think its more the examination technique too though, sometimes you trip up in the exam simply for not reading the question enough or understanding it properly...
Otherwise it is straight forward recall...
Original post by Dinaa
Hello AS Chemistry TSRians!
I thought it would be a good idea to make a thread, where students doing AS Chemistry, post/ask questions, and we could all help each other out?
Teaching another person, also helps you become more confident and you both develop a better understanding. I know there is an A-level chat thread already, but this should be for learning!
There is no such thing as a silly question, so ask away and hopefully, you'll find someone who can help you
I shall also make a list of the Chemistry students, and what exam board they're all on! So please post what exam board you are on, if you are in!
List of the students doing Chemistry!
Lovely helpers!
I apologize if I've missed anyone out, got the list from Current year 12 list! (Lazy i know)
P.S- If you don't want to, okay, you are not obliged to do so! But please, no rude/offensive comments
I thought it would be a good idea to make a thread, where students doing AS Chemistry, post/ask questions, and we could all help each other out?
Teaching another person, also helps you become more confident and you both develop a better understanding. I know there is an A-level chat thread already, but this should be for learning!
There is no such thing as a silly question, so ask away and hopefully, you'll find someone who can help you
I shall also make a list of the Chemistry students, and what exam board they're all on! So please post what exam board you are on, if you are in!
List of the students doing Chemistry!
Spoiler
Lovely helpers!
Spoiler
I apologize if I've missed anyone out, got the list from Current year 12 list! (Lazy i know)
P.S- If you don't want to, okay, you are not obliged to do so! But please, no rude/offensive comments
Put me down as a helper!
I'm a 2nd year Pharmacy student at uni but I did Edexcel chem for A-levels and got an A.
I'm not gonna be answering questions via PM but do post on here.
I'm stronger at organic chemistry than physical/inorganic chemistry it has to be said
Original post by underestimate
How you finding Unit 2 at the moment, is it harder?
I'm finding it slightly easier because so far, most of it has just been drawing and naming compounds. My friend who thought she'd enjoy organic chemistry more is really struggling with it though, so I guess it depends on the person.
Original post by TheNoobishKnight
I got my lowest score in chemistry but the questions were straightforward, I just hadn't prepared for them. Unlike Bio where the question is never straightforward lol.
I do OCR Biology.
I was very lucky, in the last 5 mins I spotted that I had completely read the question wrong on the first page, and quickly corrected it(about 7/8 marks saved there). I managed to miss an A by 1 mark, but hoping to get a strong A or even an A* this year for it
I do OCR Biology.
I was very lucky, in the last 5 mins I spotted that I had completely read the question wrong on the first page, and quickly corrected it(about 7/8 marks saved there). I managed to miss an A by 1 mark, but hoping to get a strong A or even an A* this year for it
I do Edexcel SNAB and I kid you not, it is so difficult. Content wise I'm fine but I just need to do a **** load of papers to get a decent mark this year. I know with Biology you never know what they are asking yeah, hence I get things wrong.
Original post by zhang-liao
I suffered from the same exact problem earlier in the year
Karmacrunch knows...
I didn't know what field in science I wanted to do. I was orginally planning on doing Biochemistry but then saw the graduate prospects and they weren't great
So I looked at doing Biomedical Science, Biology, Chemistry, Medicinal/Pharmaceutical Chemistry, Pharmacology or Pharmacy (Medicine wasn't for me, wanted to work in a lab-based setting & not deal with blood)
I finalised my options to Biomedical Science, Chemistry or Pharmacy and then looked further, asked for some recommendations on TSR (well not some, but many) and also at my sixth form and then did some research. Saw that Pharmacy and Biomedical Science were saturated with graduates and I didn't want patient based work so I decided that Chemistry was for me.
I enjoy it A-Level and went to my Chemistry teacher who recommended me some good universities. Manchester is really good outside London but I want to study inside London so I'm hoping to study at either Queen Mary's or UCL since they are the only Russell Group Universites which can provide me with an Industrial Year Placement alongside my degree (my Chem teacher said it was essential for find a placement/sandwich year since it helps with finding lab-based work later on) and Kings didn't provide that (although I'm considering them too) and I can't apply to Imperial for a Chemistry course because I don't have Maths...
Karmacrunch knows...
I didn't know what field in science I wanted to do. I was orginally planning on doing Biochemistry but then saw the graduate prospects and they weren't great
So I looked at doing Biomedical Science, Biology, Chemistry, Medicinal/Pharmaceutical Chemistry, Pharmacology or Pharmacy (Medicine wasn't for me, wanted to work in a lab-based setting & not deal with blood
)I finalised my options to Biomedical Science, Chemistry or Pharmacy and then looked further, asked for some recommendations on TSR (well not some, but many) and also at my sixth form and then did some research. Saw that Pharmacy and Biomedical Science were saturated with graduates and I didn't want patient based work so I decided that Chemistry was for me.
I enjoy it A-Level and went to my Chemistry teacher who recommended me some good universities. Manchester is really good outside London but I want to study inside London so I'm hoping to study at either Queen Mary's or UCL since they are the only Russell Group Universites which can provide me with an Industrial Year Placement alongside my degree (my Chem teacher said it was essential for find a placement/sandwich year since it helps with finding lab-based work later on) and Kings didn't provide that (although I'm considering them too) and I can't apply to Imperial for a Chemistry course because I don't have Maths...
I think I'm in the exact same position you were in. I wanted to do biochemistry but the graduate prospects aren't looking great. I then looked into biomedical science and saw that the people who do it want to progress into Medicine or I wouldn't know what to do with the degree. It's still one of my preferred degree choices. My brother did Pharmacy and my sister did Biochemical engineering so I've been asking them questions but I feel like neither of those degrees appeal to me. I really like the idea of Natural Sciences, but not having done maths and just Biology and Chemistry limits my choices. I may have to pick up AS/A2 Maths next year and drop two AS subjects if I am serious about this, but you need that Mathematical flair and I'm not sure I've got them, especially for an A grade its a big risk. I've looked into a pure Chemistry degree, especially because with great unis such as UCL the entry requirements are AAB which is quite low and you don't need Maths but I quite like having some Biology in it too, so I'm not sure if its for me, again its still an option. I feel like I'm waiting for an epiphany or I'll have to take a gap year.
Original post by BCMFM16
I'm terrible at both. I do OCR and I've been getting Ds so far. We did a recent controlled assessment which you have 4 other attempts at and I go 6/10 in the first section
My mum says its London's social university. They don't do dentistry unfortunately. Its only Queen's and King's. My mum says she prefers me to apply to King's as its better than Queen's apparently. This quote from a Cinderella 2 song which my younger sister is currently watching on her iPad may help you find the right career path for you :
"There's a world full of changing and you've just begun
Don't let them tell you it's simply not done
When you follow your heart you'll shine bright as the sun"
My mum says its London's social university. They don't do dentistry unfortunately. Its only Queen's and King's. My mum says she prefers me to apply to King's as its better than Queen's apparently. This quote from a Cinderella 2 song which my younger sister is currently watching on her iPad may help you find the right career path for you :
"There's a world full of changing and you've just begun
Don't let them tell you it's simply not done
When you follow your heart you'll shine bright as the sun"
Aaaw thanks, that's a great quote even though it is from Cinderella. Yeah King's is better than Queens, its more internationally recognized, but either Uni is good in terms in Science based degrees.
Original post by JohnLE
Hey guys I'm in year 10 and am hoping to do chemistry for A Level, I'm doing double science in GCSE and am at a grade B+/A- right now which is very good because I'm only in year 10 I want to ask how chemistry is at a level and what advantages does it have for further education. Also does it include a lot of maths?
I want to ask how chemistry is at a level and what advantages does it have for further education. Also does it include a lot of maths?Chemistry at AS is great atm, it's my favourite subject, but I wouldn't say it is easy. I got an A* at gcse and don't think that garuntee's me doing well.
The syllabus is changing next year for A-level sciences so can't give direct representation of that it'll be for when you do it.
Atm, there is quite a bit of calculations so choose maths with it aswell
Original post by noshahmad
I think I'm in the exact same position you were in. I wanted to do biochemistry but the graduate prospects aren't looking great. I then looked into biomedical science and saw that the people who do it want to progress into Medicine or I wouldn't know what to do with the degree. It's still one of my preferred degree choices. My brother did Pharmacy and my sister did Biochemical engineering so I've been asking them questions but I feel like neither of those degrees appeal to me. I really like the idea of Natural Sciences, but not having done maths and just Biology and Chemistry limits my choices. I may have to pick up AS/A2 Maths next year and drop two AS subjects if I am serious about this, but you need that Mathematical flair and I'm not sure I've got them, especially for an A grade its a big risk. I've looked into a pure Chemistry degree, especially because with great unis such as UCL the entry requirements are AAB which is quite low and you don't need Maths but I quite like having some Biology in it too, so I'm not sure if its for me, again its still an option. I feel like I'm waiting for an epiphany or I'll have to take a gap year.
I think I'm in the exact same position you were in. I wanted to do biochemistry but the graduate prospects aren't looking great. I then looked into biomedical science and saw that the people who do it want to progress into Medicine or I wouldn't know what to do with the degree. It's still one of my preferred degree choices. My brother did Pharmacy and my sister did Biochemical engineering so I've been asking them questions but I feel like neither of those degrees appeal to me. I really like the idea of Natural Sciences, but not having done maths and just Biology and Chemistry limits my choices. I may have to pick up AS/A2 Maths next year and drop two AS subjects if I am serious about this, but you need that Mathematical flair and I'm not sure I've got them, especially for an A grade its a big risk. I've looked into a pure Chemistry degree, especially because with great unis such as UCL the entry requirements are AAB which is quite low and you don't need Maths but I quite like having some Biology in it too, so I'm not sure if its for me, again its still an option. I feel like I'm waiting for an epiphany or I'll have to take a gap year.
Chemistry degrees do generally have quite low entry requirements in comparison to other science-related degrees such as Medicine so I do agree with you there
I also had that issue with wanting a mixture of Biology and Chemistry so I looked at possible degrees which combined Chemistry and Biology and found some but they didn't provide an industrial year placement and the very few degrees which did were from universities outside London. Kings College London have a combination of Biomedicine and Chemistry (which is accredited by RSC - Royal Society of Chemistry) but they don't provide an industrial year placement and I see that as essential if I want to prosper in a career for Chemistry since I'll have that first-hand experience.
Imperial have this amazing combination (a 5 year MSci and an Industrial Year Placement with Medinical Chemistry) but as mentioned before, since neither of us have Maths A-Level and Imperial except Maths as a part of their entry requirement
If you do want a combination of some sort, you might want to consider Pharmacology or Pharmacy (though Pharmacy isn't a great great degree since it has been saturated with jobs over the years recently). If you particularly interested in working for the pharmaceutical industry but want that aspect of Biology, Microbiology might be a degree to consider.
Hope what I've said helps to an extent with your decision, I had a similar problem as to what degree choice I wanted to do and I couldn't find anything that combined my interest of Biology and Chemistry and its graduate prospects looked good.
Good luck with your degree choice though 
Original post by zhang-liao
Chemistry degrees do generally have quite low entry requirements in comparison to other science-related degrees such as Medicine so I do agree with you there
I also had that issue with wanting a mixture of Biology and Chemistry so I looked at possible degrees which combined Chemistry and Biology and found some but they didn't provide an industrial year placement and the very few degrees which did were from universities outside London. Kings College London have a combination of Biomedicine and Chemistry (which is accredited by RSC - Royal Society of Chemistry) but they don't provide an industrial year placement and I see that as essential if I want to prosper in a career for Chemistry since I'll have that first-hand experience.
Imperial have this amazing combination (a 5 year MSci and an Industrial Year Placement with Medinical Chemistry) but as mentioned before, since neither of us have Maths A-Level and Imperial except Maths as a part of their entry requirement
If you do want a combination of some sort, you might want to consider Pharmacology or Pharmacy (though Pharmacy isn't a great great degree since it has been saturated with jobs over the years recently). If you particularly interested in working for the pharmaceutical industry but want that aspect of Biology, Microbiology might be a degree to consider.
Hope what I've said helps to an extent with your decision, I had a similar problem as to what degree choice I wanted to do and I couldn't find anything that combined my interest of Biology and Chemistry and its graduate prospects looked good. Good luck with your degree choice though
I also had that issue with wanting a mixture of Biology and Chemistry so I looked at possible degrees which combined Chemistry and Biology and found some but they didn't provide an industrial year placement and the very few degrees which did were from universities outside London. Kings College London have a combination of Biomedicine and Chemistry (which is accredited by RSC - Royal Society of Chemistry) but they don't provide an industrial year placement and I see that as essential if I want to prosper in a career for Chemistry since I'll have that first-hand experience.
Imperial have this amazing combination (a 5 year MSci and an Industrial Year Placement with Medinical Chemistry) but as mentioned before, since neither of us have Maths A-Level and Imperial except Maths as a part of their entry requirement
If you do want a combination of some sort, you might want to consider Pharmacology or Pharmacy (though Pharmacy isn't a great great degree since it has been saturated with jobs over the years recently). If you particularly interested in working for the pharmaceutical industry but want that aspect of Biology, Microbiology might be a degree to consider.
Hope what I've said helps to an extent with your decision, I had a similar problem as to what degree choice I wanted to do and I couldn't find anything that combined my interest of Biology and Chemistry and its graduate prospects looked good.
Good luck with your degree choice though Found both of your posts interesting. I wanted to do medicine, but messed AS up, may still apply for it if I get much better in this gap year(I got D for chem and the rest were not very far of A)
But anyway I really liked the look of biochemistry for some reason
1) maths not needed, I am not good at it as I haven't done it past GCSE.
2) Bio + Chem, I enjoy them both a lot
3) Job as a researcher or a teacher in either bio or chem!
However there is a big Con from what I read.
1) jobs are hard to find and the jobs don't pay all that great(which isn't much of a problem if you don't care about money, but still is a con). Many people go and do accountancy after biochemistry and related as the jobs are saturated.
I enjoyed reading your posts, I looked for some good unis that do chem without maths and I read somewhere UCL or something which is interesting! I guess I got to keep researching!
Original post by noshahmad
x
Aah yes, just remembered, you might want to consider signing up to ChemNet for help in regards to careers advice. I know its Chemistry-focussed but I'd recommend it since other members might be able to help hopefully
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