Chemistry 3/4 2013 Thread

[teletubbies_95]

In aspirin formation, do we need to know about the two pathways (ie. pathway number 1= using carboxylic acid and alcohol , ie . salicylic acid and acetic acid and pathway number 2 (faster reaction)= first adding acetic acid together to make ethanoic anhydride ,and adding it to salicylic acid , to make aspirin)  ? or only one pathway ( i.e. pathway 1) ?

[Curry_bro]

In aspirin formation, do we need to know about the two pathways (ie. pathway number 1= using carboxylic acid and alcohol , ie . salicylic acid and acetic acid and pathway number 2 (faster reaction)= first adding acetic acid together to make ethanoic anhydride ,and adding it to salicylic acid , to make aspirin)  ? or only one pathway ( i.e. pathway 1) ?

if this is 35 material... im getting a 10 O.O

btw, im pretty sure you that knowing both pathways would be better. just keeps you on the safe side haha

[Aurelian]

In aspirin formation, do we need to know about the two pathways (ie. pathway number 1= using carboxylic acid and alcohol , ie . salicylic acid and acetic acid and pathway number 2 (faster reaction)= first adding acetic acid together to make ethanoic anhydride ,and adding it to salicylic acid , to make aspirin)  ? or only one pathway ( i.e. pathway 1) ?

Know both.

As an aside, the second pathway isn't simply a "faster" reaction; it will actually give you a much better yield. In the first pathway, the produced water will react with the aspirin you make and reduce your yield quite a bit.

[Homer]

if this is 35 material... im getting a 10 O.O

I'm getting 5 scaled up 

[thushan]

Oi. All of you. I have one word for you: confidence.

Don't do what I did last year (first year uni).

[Mr Keshy]

It seems like other people will know more than you, just make sure you have confidence Read your textbook and do the questions. Motivate yourself too, if you're confused by other peoples questions, find out where they are, and see if you're up to it. If you aren't, why are you stressing? If you're up to it or have done it. Revisit it again. Take 5-10 minutes and have a look. Take more if you have to. I did this... numerous times , and it works very well.

[Aurelian]

Also probably good to remember that the school year hasn't even started yet D=

[teletubbies_95]

Ohkay ! Thanks ! do we need to know exactly which one produces more and which one doesnt? because i think i might forget :0

and guys , you guys are so smart ! i know that from reading your posts! Dont underestimate yourselves!

curry bro and homer. you guys will get 40+ for sure !

[Stick]

Oi. All of you. I have one word for you: confidence.

Don't do what I did last year (first year uni).

This. While teletubbies_95 has definitely done a lot of work these holidays and clearly has a good grasp on the information, I see countless people on these forums work ahead and do well on the SACs and then flunk their exams because they didn't develop a solid foundation of their knowledge. This was something I experienced last year with Further Maths and luckily I was able to address it in time. This is one reason why I have chosen not to work ahead during these holidays and instead only complete what I have to (the other reason being that I needed to give myself an adequate break). There is no point rushing through the course otherwise.

[teletubbies_95]

Nahh. I havent been doing much. Just looking through the book and familirising myself with everything, so i dont freak out , when i start , like I did for Biology last year . I 've just been chilling , going to the beach , watching curry movies etc. I guess it also depends on the person to, the way they remember stuff , personal life , etc.. when exams come up so we cant generalise !

But anyhow, dont underestimate yourselves
And ask more questions! 

[Stick]

I'm sure your version of "not doing much" is doing far more than what I've been doing for Chemistry (literally "not much" ).

[saba.ay]

Could someone please explain UV-visible spectroscopy ? I have a slight understanding of it, but I don't understand it completely. Please and Thank you.

[thushan]

Could someone please explain UV-visible spectroscopy ? I have a slight understanding of it, but I don't understand it completely. Please and Thank you.

In essence, coloured compounds or compounds that absorb UV light can have their concentrations measured by checking how much light of a particular wavelength it can absorb. The higher the concentration of the compound, the more light at that wavelength it can absorb. Turns out that for low concentrations, the relationship between absorbance and concentration is linear.

[Mr Keshy]

In essence, coloured compounds or compounds that absorb UV light can have their concentrations measured by checking how much light of a particular wavelength it can absorb. The higher the concentration of the compound, the more light at that wavelength it can absorb. Turns out that for low concentrations, the relationship between absorbance and concentration is linear.

That's interesting from a general point of view! Cool!



In other news, I just finished the summary questions for chapter two of the Heinemann book. Flipped over to do the Chapter 2 Review and immediately had a heart attack.

(those using the same book will get what I'm saying, Page 25)

[saba.ay]

In essence, coloured compounds or compounds that absorb UV light can have their concentrations measured by checking how much light of a particular wavelength it can absorb. The higher the concentration of the compound, the more light at that wavelength it can absorb. Turns out that for low concentrations, the relationship between absorbance and concentration is linear.

Thank you. That really simplifies it.

In other news, I just finished the summary questions for chapter two of the Heinemann book. Flipped over to do the Chapter 2 Review and immediately had a heart attack.

(those using the same book will get what I'm saying, Page 25)

They're not too bad once you start them. I mean most of the questions are the same, as in, they require the same process/working out.