Chemistry 3/4 2013 Thread

[polar]

you can take it a step further and put \mathrm{ before the equation to have the equation in roman font instead of maths mode:

Code: [Select]

\mathrm{CH_4_{(g)} + 2O_2_{(g)} \to CO_2_{(g)} + 2H_2O_{(g)}} gives

[Mr Keshy]

It does look very confusing at first, but I'm sure that in time and given my rate of question asking, it'll become second nature

[Mr Keshy]

Does anyone have the worked solutions to the Heinemann 2 Chem book? It would really come in handy I think. (some might abuse it though)

I really can't figure out how to approach this question. It might be the time at which I'm undertaking it but I'm not too sure yet.

I've done all the other questions in this specific chapter with no issues, this is the question for 2.2.

3. A sample of blue copper(II) sulfate crystals weighing 2.55 g
is heated and decomposes to produce 1.63 g of anhydrous copper(II) sulfate. Show that the formula of the blue crystals is CuSO4.5H2O.

Any direction would be appreciated

[ggxoxo]

Step 1   Calculate the amount of anhydrous copper sulfate.
      n(CuSO4) = 
         = 
         = 0.0102 mol
Step 2   Calculate the amount of water in hydrated copper sulfate.
      n(H2O)   = 
         = 0.0511 mol
Step 3   Calculate the ratio of amount of anhydrous copper sulfate to amount of water.
          = 
            = 5
       The formula of the crystals is CuSO4•5H2O.

[Stick]

Does anyone have the worked solutions to the Heinemann 2 Chem book? It would really come in handy I think. (some might abuse it though)

I really can't figure out how to approach this question. It might be the time at which I'm undertaking it but I'm not too sure yet.

I've done all the other questions in this specific chapter with no issues, this is the question for 2.2.

3. A sample of blue copper(II) sulfate crystals weighing 2.55 g
is heated and decomposes to produce 1.63 g of anhydrous copper(II) sulfate. Show that the formula of the blue crystals is CuSO4.5H2O.

Any direction would be appreciated

This question has been asked before. Use the empirical formula method.

[Mr Keshy]

This question has been asked before. Use the empirical formula method.

I was having troubling with figuring out what anhydrous copper sulfate and the hydrated part. All makes sense now.
Curry bro asked the same question, my bad.

Step 1   Calculate the amount of anhydrous copper sulfate.
      n(CuSO4) = 
         = 
         = 0.0102 mol
Step 2   Calculate the amount of water in hydrated copper sulfate.
      n(H2O)   = 
         = 0.0511 mol
Step 3   Calculate the ratio of amount of anhydrous copper sulfate to amount of water.
          = 
            = 5
       The formula of the crystals is CuSO4•5H2O.

Thank you

[teletubbies_95]

In the general structure of amino acids, in the Heinemann book, the side branches are called the Z group , but in an other textbooks , it's called the R group? Which one is right in vcaa exams or is it used interchangeably ?



Can only  2-amino acids exist or are there other types ?

[Reckoner]

Does anyone have the worked solutions to the Heinemann 2 Chem book? It would really come in handy I think. (some might abuse it though)

I think they are found on the CD that comes with the textbook (if you have it). They're not AN study guide standard, but are much better than the answers at the back of the textbook.

[teletubbies_95]

Kesh.. I have them on word doc. If any of you guys want it , just pm your emails and ill send them to you!

[Stick]

In the general structure of amino acids, in the Heinemann book, the side branches are called the Z group , but in an other textbooks , it's called the R group? Which one is right in vcaa exams or is it used interchangeably ?



Can only  2-amino acids exist or are there other types ?

You're already this far into the textbook?! I think someone needs to take a break!

In Biology it's referred to as the R group, so I'm not too sure. And there's definitely more than 2 amino acids that exist. In the body, there's 20 but from memory over 250 can be made artificially.

[REBORN]

2-amino acids means alpha-amino acids. Not as in numerical 2. As for the answer, I'm not sure.

[Stick]

Oh. :|

[Mr Keshy]

I think they are found on the CD that comes with the textbook (if you have it). They're not AN study guide standard, but are much better than the answers at the back of the textbook.

They're far better than the standard answers. It's only when I get them wrong though, I can easily figure out where I went wrong.

Kesh.. I have them on word doc. If any of you guys want it , just pm your emails and ill send them to you!

Will do

[Aurelian]

In the general structure of amino acids, in the Heinemann book, the side branches are called the Z group , but in an other textbooks , it's called the R group? Which one is right in vcaa exams or is it used interchangeably ?

I don't think it especially matters. I've seen both "Z" and "R" notation, as well as even "G" notation elsewhere. As long as it is clear what you're referring to, I doubt examiners would care what letter you assign to the side-group. Still, if in doubt, probably go with "R" group, since this seems to be the most common nomenclature for amino acids.

Can only  2-amino acids exist or are there other types ?

Other amino acids can definitely exist, but the biologically significant ones pretty much exclusively alpha-amino acids. Certainly all 21 of the protein-forming amino acids in eukaryotes are of the alpha variety.

[Mr Keshy]

I should probably get Chem tutoring