Volume released question? (1 Viewer)

[speersy]

In the JRAHS HSC trial 2003

Calculate the volume of carbon dioxide released in the fermentation process when 2.75 grams of CO2 is released.
I was wondering since there is two moles of CO2, wouldn't u times the answer by 2?

 

[Tommy_Lamp]

C6H1206 --> 2 C2H5OH + 2 CO2

2xmoles glucose = moles of CO2
2(m/mm) = v/mv

etc.

 

[speersy]

could someone also please help me with this problem.

when determining say the pH of a H2SO4 solution we multiply the H+ concentraion be two as the acid is diprotic
how come then when determining the H+ concentration in citric acid witha Ph of 2.1 we don't divide the answer by 6?

 

[Tommy_Lamp]

You cant determine the H+ concentration of citric acid, it is a weak acid, you cant get asked that. you can only be asked to find a strong acid or OH- in a base.

 

[VVoody]

I'm not even sure we can be asked the OH- of a base...I think my chem teacher was saying how stupid it was that it wouldn't be asked

 

[Tommy_Lamp]

its easy, if they say to determine the OH- concentration of say, NaOH, you just do
14 + log [H+] because [OH-] + [H+] = 14

 

[speersy]

fair enough i thought that was the case, just thought i'd check up

bloody Ruse

 

[Tommy_Lamp]

I avoid James Ruse trials, they are generally way over the syllabus and ask questions that have been specifically taught in their classes. Better to stick to general papers like CSSA, ARC, Independant etc. and of course HSC papers

 

[VVoody]

Yea, I know that finding OH- is easy, but it's not specified that we need to know it in the syllabus. Obviously they seem to think it's too hard for us to comprehend such a concept...

 

[Tommy_Lamp]

Yes, yet in Physics we learn Special Relativity..oh the simplicity.

 

[Paroissien]

Jeez they seem to have dumbed down the chemistry syllabus

 

[jumb]

You cant determine the H+ concentration of citric acid, it is a weak acid, you cant get asked that. you can only be asked to find a strong acid or OH- in a base.

This years independent trial asked a quetion about that. However they gave you numbers, eg pH = 3, find hyrogren's etc

 

[wind]

Ruse trials are crazy!

Their mark allocations are so tight! A one mark question for a page of calculation lol

 

[speersy]

yeah draw the structure of citiric acid
thanks, 1 mark!