Chemistry?

[Tilda]

Could anybody give me a hand with this please?

https://forums.freddyshouse.com/showthread.php?t=213173

Any tips and hints would be much appreciated.

 

[leggy]

leggy, you do not have permission to access this page. This could be due to one of several reasons

I assume this thread is in the DAoC forum which alot of us have opted never to see ever again.

If you'd like to re-post it here someone might be able to help.

 

[pcg79]

My sisters stuck on her A level chemistry coursework. Shes not allowed teacher help and our entire family (3x A level chemistry) are stumped.
Tris et al. can you give us a hand?

Question is;

Aim, to calculate the relative formula mass of succinic acid and its molecular formula by titration with sodium hydroxide.
In a titration of succinc acid and sodium hydroxide, what calcuation would you use to find "n" in the equation HOOC(CH[little2])[little]n COOH

Her teacher apparently says to make up values for the titration volume etc.
We know that the "n" should equal 2, but we can't work out how to prove this using titration calcuations.

Can anybody give us a shove/hand in the right direction.(or do it for us?!)

there!

 

[Draylor]

Easy

 

[old.Tohtori]

Tilda. My gods. Don't you know that you could get bummed, banned, flocked and neutered for linking to Those There Forums We Should Not Speak Of(tm)

You could get your mod privilages stripped, as well as your undies.

 

[Chilly]

with titration, if you know the concentration and the amount (moles of stuff and volume) you can work out what reaction is going on and prove a chemical formula. I cba doing this problem all the way through, I passed my A level chemistry and I've no intention of remembering any of it.

 

[Paradroid]

Could anybody give me a hand with this please?

https://forums.freddyshouse.com/showthread.php?t=213173

Any tips and hints would be much appreciated.

I really don't have any chemistry related tips and hints. These days anyone who does is liable to end up with 200 policemen fisting them at 3am. Wait, there's one...


Hint:
If you do attract the attention of the security forces by compiling an online chemistry hints'n'tips, keep a jar of KY jelly handy for when the 200 policemen arrive at 3am.





...or is that a tip?

 

[Gat_Decor]

Dunno if this helps, asked my Dad the question set, here's his reply:-

COOH(CH2)nCOOH + 2NaOH

depending how much naoh you need then succinic acid needs half as much.

 

[Arnie 2Tone]

I knew my degrees would come in handy one day!

Right, succinic acid has 2 protons that will react with NaOH, therefore:

HOOC(CH2)nCOOH + 2NaOH --> NaOOC(CH2)nCOONa + 2 H2O

So you need 2 moles of NaOH per mole of succinic acid for a balanced reaction. Therefore to calculate the value of n, you should dissolve a known mass of succinic acid (say 1g) in a fixed quantity of distilled water (say 50ml). Titrate this with an indicator to the reaction end-point by adding a known concentration of NaOH. The molar concentration of succinic acid in the 50ml of solution is therefore given by:

([NaOH] x volume) / 2 = [HOOC(CH2)nCOOH]

Dividing the molar concentration of succinic acid by 20 (because 20 x 50ml = 1000ml) gives the number of moles of succinic acid that were in the 50ml of solution. Dividing 1 by that value gives the relative molecular mass of succinic acid (should be very close to the true value of 118).

Each COOH group contributes 45 to the relative molecular mass. Each CH2 group will contribute 14. Therefore:

n = 118 - 90 / 14

therefore n = 2.

You can cobble all of the above into a single equation, but it would look incredibly messy trying to do it without a proper equation writing tool. I'm fairly certain that's all correct, but it's off the top of my head, so check it thoroughly!!

 

[Arnie 2Tone]

In the first equation:

([NaOH] x volume) / 2 = [HOOC(CH2)nCOOH]

That's the volume of NaOH added, not the volume of succinic acid used.

 

[pez]

I concur?

 

[Tilda]

Thanks all, especially Arnie
Got it sorted now!