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Sulfuric Acid (1 Viewer)

Aerlinn

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Some questions:
1. If you were designing a sulfuric acid plant, briefly list important factors that you would consider when deciding:
a. Whether to use powdered sulfur from a local supplier or molten sulfur transported a greater distance
Cost of transport?
b. If sulfur were to be burnt in air or oxygen
which process is more energy and cost efficient, whether it's necessarily to extract oxygen from air first?
c. Whether to obtain sulfur dioxide by burning sulfur or from the waste gases of a copper smelter
d. Which catalyst to use, platinum or vanadium (V) oxide
Which one's less expensive? A sheet I have says you also have to consider 'the chance of the catalyst being "poisoned"' :confused:
e. whether to use air or oxygen for the reaction in the converter.
I did come up with some for some of them, there could be more. Others, I'm not sure about...

2. Air is thoroughly purified before it is used in the Contact process (for production of sulfuric acid). Suggest reasons for this.
Answer says: 'to prevent poisoning of the catalyst'. Again, i have no idea what this means.

3. During the Contact process, as gas passes through each catalyst bed in the converter, its temperature increases. The gas must be diverted for cooling before returning for another pass.
a. Why does the temperature of the gas rise?
Is it because the reaction's exothermic?
b. Why is it necessary to cool the gas?
To prevent converter from heating up too much?
c. What side-benefit is obtained from the need to cool gases?

4. What other industries (apart from sulfuric acid plants) emit sulfur dioxide?

Thanks :) :)
 

xiao1985

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uhm... how weird of questions... iirc, these are from industrial chem?
i didn't do industrial chem, but i will try my best to answer them... most of them, however, you probably want to double check them...

1)

a)uhm... both have adv and dis adv...
powder: can be stored at room (less energy required), but have higher SA so may have a higher chance of being containminated
molten: reverse of powder

b) again, there are adv and disadv for both:
air: cheaper, less violent reaction
pure oxygen: less side reaction

c)definitely waste from smelting: cost efficient

d) V2O5 IMHO, Pt has a HIGH affinity to S, and Pt - S compound is highly stable and won't react easily.

e) air has impurities such as CO, which may deactivate the catalyst

Q2 same as above

q3 a) synthesis reaction - bond formation ALWAYS release heat (IIRC, contact process is 2SO2 + O2 ---> 2SO3; SO3 + H2O ---> H2SO4; H2SO4 + SO3 ---> H2S2O7)
b) if you let the temperature increase without limit, you are literally setting off a bomb... (increasing temperature = heating gas/liquid ---> kaboom) also, higher temperature means the container wears out faster...
c) cool gas ---> liquify ---> take out of system ----> drive equilibrium tothe right

4) metal smelting plant
 

xiao1985

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ellen.louise said:
copyright to moppy:

Little Johnny had a drink
but drink he would no more,
for what he thought was H2O
was H2SO4...
lol, i never got what does this mean... does it mean sulfuric acid is highly corrosive hence 'but he would drink no more'?!
 

Aerlinn

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Heh, poor Johnny ^^ Nice rhyme!

3c) I would've thought it would've just shifted equilibrium to the right 'cause of the exothermic reaction and everything. Maybe what you said was the same thing...

Another sulfuric acid question: Why does a solution of sulfuric acid labelled 0.050M H2SO4 have a pH of 1.3 rather than 1.0?
 

xiao1985

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2nd step of ionisation is not 100%

edit: cool sig btw
 

Aerlinn

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Thanx :)
Ah yes, i remember being told that, I think. So we'd find [H+] in the second ionisation by treating HSO4- as a weak acid then add the [H+]'s together?
(I also remember that before we did this stuff, we used to calculate pH's by going, eg. for this one, [H+]= 2* 0,050M Now why on earth did we do that?!)
 

xiao1985

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correct, you treat HSO4 - as a weak acid

well... you have been lied too.... it should have never being 2*0.05 when you are calculating pH...
 

Aerlinn

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I see...
~~~

Something I wanted to clarify: you get sulfur/ sulfur dioxide from incomplete combustion of H2S in natural gas/ crude oil...
3H2S(g) + O2(g) ---> 2H2S(g) + 3S(g) + SO2(g)
Is that done as part of the desulfurisation process? ie. removing sulfur-containing compounds in the crude oil to not damage environment, etc.?
 

xiao1985

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never thought about that... but looks fine....

cept the process need to be carefully monitored... the wrong condition can cause the combustion of crude oil along with sulfur...
 

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