Chem qu (1 Viewer)

[velox]

What answer do u get when u calculate this?

 

[richz]

A
cuz sulfuric acid is diprotic so u multiply the concentration of h2so4 by 2

 

[Dreamerish*~]

A
cuz sulfuric acid is diprotic so u multiply the concentration of h2so4 by 2

YAY! Smartness.

 

[velox]

Thanks. What module is this from?

 

[nit]

Acids and Bases. Dodgy q, dodgy answer

 

[velox]

Ooops should have figured. Still 64% of band 6 students managed to get it right.

 

[richz]

Acids and Bases. Dodgy q, dodgy answer

not really its a nice trick that catches a lot of people

 

[Dreamerish*~]

Thanks. What module is this from?

Acidic Environment, although it could be of some use in Monitoring.

 

[nit]

No, bisulfate ion is a weak acid with pKa of 1.92 I think. Hence you can't assume it deprotonates fully, as it can't unless in the presence of base.

 

[velox]

How about this qu?
<a href="http://img37.imageshack.us/my.php?image=chemqu3wz.jpg" target="_blank"><img src="http://img37.imageshack.us/img37/9901/chemqu3wz.th.jpg" border="0" alt="Free Image Hosting at www.ImageShack.us" /></a>

 

[richz]

lol this is a time consuming one, just get the molar mass and multiply the kj/g and one shud match up with the one wanted

edit answer is C

 

[nit]

not time-consuming at all. Just multiply the molar mass of the compounds by the figures given. It leaps out at you.

 

[richz]

well i have to draw out the structure then work out the mass, isnt that time consuming??

 

[velox]

damn i memorised the formula wrong

 

[nit]

well you should be able to write down the molecular formulae of these simple alcohols.
Edit: which formula?

 

[Ghost1788]

how do go from ph=-loge[H+]
to
[H+]=...

what does [H+] equal i just cant remember...

 

[richz]

10^(-pH) just do the opposite

and also pH doesnt = - loge[H+]

pH = -log (10) [H+]

 

[velox]

CH3CH2CH2OH --> formula of propanol

 

[richz]

yes nit i know but it takes longer than most multis

 

[velox]

im assuming most band 6 ppl get 100% in multi?