Biology; Chemistry; Physics: Post your doubts here!

[Spidey21]

i know this formula but doesn't structure mean dat dot and cross diagram showing all atoms and number of sharing electrons?

h h h
| | |
h-c-c-c-c=o
| | | |
h h h 0-h
hope this answers...

 

[Tharindu]

http://www.mediafire.com/download.php?s22a77xhlcb0hnm

download physics and chem presentations from here

Thanks alot

 

[Spidey21]

i know this formula but doesn't structure mean dat dot and cross diagram showing all atoms and number of sharing electrons?

http://www.scienceforums.net/uploads/butanoic acid.jpg

this is exactly how its supposed to be..

 

[ashiqbal]

Thanks alot

these presentations were made by me and my class fellows, so there might be a little confusion... dont forget to ask!

 

[scouserlfc]

Well here's a problem i posted this last year and no one replied then,i had completed the syllabus and only this is left for quite sometime ,so can u please help now !

here is that syllabus point again

the use of calcium carbonate to reduce the effect of ‘acid rain’ and in flue gas desulfurisation

can u just give me the essential equations,the brief details of the process and or refer to a website which explains this ???

 

[ashiqbal]

u know what, i got the same question in mocks that how can calcium carbonate be used to reduce effect of acid rain for two marks in chemistry, and i once solved a paper in which it was written one compound which is used in flue gas desulfirisation, which my teacher told me could be calcium carbonate or aluminium carbonate.

my mocks result is on tuesday, so i will ask my teacher what is the exact answer and post here, if u can wait!

 

[scouserlfc]

u know what, i got the same question in mocks that how can calcium carbonate be used to reduce effect of acid rain for two marks in chemistry, and i once solved a paper in which it was written one compound which is used in flue gas desulfirisation, which my teacher told me could be calcium carbonate or aluminium carbonate.

my mocks result is on tuesday, so i will ask my teacher what is the exact answer and post here, if u can wait!

sure thing i have waited for a year as i posted this question last year take your time !

 

[ashiqbal]

maybe this could help u a bit:
REACTION OF ACIDS WITH CARBONATES or HYDROGEN CARBONATES

• Contrary to what some textbooks may say, but often do not point out, all carbonates are bases and react with acids to form salts, the difference in reaction with alkalis or insoluble bases is that carbon dioxide gas is evolved.
• On adding a solid carbonate or hydrogencarbonate to an acid you see effervescence from carbon dioxide gas and the general word equation is ...
  • metal carbonate or hydrogencarbonate + acid ==> a salt + water + carbon dioxide
    
  • 
    
    Note: Using sulphuric acid and calcium carbonate you don't get much of a fizz! because the calcium sulphate salt formed, is not very soluble, and coats the remaining calcium carbonate inhibiting the reaction! This will happen with any reaction between an acid and a water insoluble reactant which forms an insoluble solid product!

 

[ashiqbal]

sure thing i have waited for a year as i posted this question last year take your time !

 

[SalmanPakRocks]

help.

 

[scouserlfc]

help.
View attachment 5878

Wait a minute post the whole of this question here or tell me the year i think they will tell u abt energy given of by hydrogen or chlorine or something ??

 

[Alchemist4lyf]

Well here's a problem i posted this last year and no one replied then,i had completed the syllabus and only this is left for quite sometime ,so can u please help now !

here is that syllabus point again

the use of calcium carbonate to reduce the effect of ‘acid rain’ and in flue gas desulfurisation

can u just give me the essential equations,the brief details of the process and or refer to a website which explains this ???

Well, I think I might have an answer to your questions. The first part is basically easy because carbonates react with acids to form a salt, water and carbon dioxide. The pH of soils, increase as a result. I assume you already know the basic equations for this one.
As for the second part, I have my teachers notes with me, and desulfurization is described here as using limewater or wet limestone which reacts with flue gases such as SO2.
The equation is: SO2 + Ca(OH)2 -----> CaSO3 + H20.
Now, you might say this is for limewater, not limestone. I looked at WikiPedia, and here's the equation for that: CaCO3 + SO2 ----> CaSO3 + CO2. This is the basic equation. On another site, it says that this happens because CaCO3 breaks up into CaO (alkaline) which reacts with SO2 (acidic). Not sure about this one, but the equation is correct. Hope I helped.

 

[scouserlfc]

Well, I think I might have an answer to your questions. The first part is basically easy because carbonates react with acids to form a salt, water and carbon dioxide. The pH of soils, increase as a result. I assume you already know the basic equations for this one.
As for the second part, I have my teachers notes with me, and desulfurization is described here as using limewater or wet limestone which reacts with flue gases such as SO2.
The equation is: SO2 + Ca(OH)2 -----> CaSO3 + H20.
Now, you might say this is for limewater, not limestone. I looked at WikiPedia, and here's the equation for that: CaCO3 + SO2 ----> CaSO3 + CO2. This is the basic equation. On another site, it says that this happens because CaCO3 breaks up into CaO (alkaline) which reacts with SO2 (acidic). Not sure about this one, but the equation is correct. Hope I helped.

yeah thanks but i would also like a few details as well although i get it that this helps as it traps acidic oxides by converting them into an insoluble solid !

 

[Alchemist4lyf]

yeah thanks but i would also like a few details as well although i get it that this helps as it traps acidic oxides by converting them into an insoluble solid !

Exactly..

 

[SalmanPakRocks]

Wait a minute post the whole of this question here or tell me the year i think they will tell u abt energy given of by hydrogen or chlorine or something ??

Here.

 

[Alchemist4lyf]

Here.

Here you go Salman. I hope I'm right. The answer's right, so probably the method is too.

H2 + Cl2 ==> 2HCL.
1 mol of H2 gives 2 moles of HCL.
so 2.5/2 moles of H2 gives 2 moles of HCl.

Now, from the equation, we see that when 2 moles of HCL are formed, energy is -184Kj.
so by ratio, when 2.5 are formed, it is:

2 moles = -184Kj
2.5 moles = x Kj. x = 230 Kj (Cross Multiplication). And that, I believe is the answer.

 

[SalmanPakRocks]

Here you go Salman. I hope I'm right. The answer's right, so probably the method is too.

H2 + Cl2 ==> 2HCL.
1 mol of H2 gives 2 moles of HCL.
so 2.5/2 moles of H2 gives 2 moles of HCl.

Now, from the equation, we see that when 2 moles of HCL are formed, energy is -184Kj.
so by ratio, when 2.5 are formed, it is:

2 moles = -184Kj
2.5 moles = x Kj. x = 230 Kj (Cross Multiplication). And that, I believe is the answer.

Thanks for the help. got it.

 

[ashiqbal]

Now, you might say this is for limewater, not limestone. I looked at WikiPedia, and here's the equation for that: CaCO3 + SO2 ----> CaSO3 + CO2. This is the basic equation. On another site, it says that this happens because CaCO3 breaks up into CaO (alkaline) which reacts with SO2 (acidic). Not sure about this one, but the equation is correct. Hope I helped.

yes calcium carbonate can thermally decompose to calcium oxide and CO2

 

[ashiqbal]

Thanks for the help. got it.

hello salman, hoping u could help me again this year.

 

[SalmanPakRocks]

hello salman, hoping u could help me again this year.

Insha'Allah bro