Qualification > Sciences
Chemistry Help HERE ONLY !!
MaNa:
--- Quote from: Bani on May 27, 2009, 10:53:59 pm ---
--- Quote from: Bani on May 27, 2009, 10:48:58 pm ---
--- Quote from: ManaH on May 27, 2009, 10:34:01 pm ---
--- Quote from: Bani on May 27, 2009, 07:59:39 pm ---
--- Quote from: ManaH on May 27, 2009, 07:20:38 pm ---Can someone explain me Q5 (p3 M/J 08)
its equlibirum i
i need to understand
I POSTION OF EQULIBRUM n WHAT HAPPENEDS ??? ???
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Q5ai) The concentration of the reactants will increase (as the equilibrium shifts to the left) and the concentration of the products will decrease.
*Equilibrium justmeansthe 'balance' of a reaction; when it says the equilibrium shifts left, it refers to the fact that the reaction goes backwards and instead of producing more products, the reactants are produced.
5aii)-The position shifts to the left because decreasing the pressure on the reaction favours the side of the equation with the highest volume of gases (a.k.a. moles/molecules of gas).
5b)-The forward reaction is exothermic, because a decrease in temperature favours the forward reaction, so it must be exothermic.
Our teacher told us to think of the equlibrium like this: there is a naugty boy and he does exactly the opposite of what you tell him to do. So, using the above scenario, lowering the pressure favours the side with higher volume of gas. And, lowering the temperature favours the exothermic temperature (heat given out). If you see, in both the cases the opposite is happening.
I hope its clear :)
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tha really helped me thankyou soo much + rep for u By the way i have one question so during a rection the conditions should be EXOTERMIC OR ENDOTERMIC??
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Endothermic is when energy is taken in, which happens when bonds are broken. Exothermic is heat given out, and this happens when new bonds are formed. In a reaction, endothermic and exothermic happens simultaneously. What determines the overall type of the reaction is this: if they tell you in a question that the energy change is -115 celsius, for example, the minus sign would indicate that the heat energy given out is more than heat energy taken in. So, the overall reaction is exothemic. Consequently, if its a positive sign, tht would indicate that heat energy taken in is more than heat energy given out, indicating that the reaction is endothermic. Also, sometimes, in question they ask you to explain why the reaction is exothermic or endotermic. In that case, you would answer using the idea of bond forming and bond breaking and the relative energy changes involved (as I have explained above).
I hope this helped. :)
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Oh, and in the case of the question fro M/J 08, it is where you have to combine the equilibrium knowledge with the exo/endo knowledge. You know that in equilibrium Qs, the opposite happens. So, if you COOL the reaction, it will try to HEAT up and increase its temp, which is by giving out heat energy (EXOTHERMIC)
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THanx alot + rep 4 u:)
Bani:
You are most welcome :)
MaNa:
--- Quote from: Bani on May 27, 2009, 11:00:37 pm ---You are most welcome :)
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ookay but i used tog et confused bcuz its kinetic thoer incres temp reaction increses but in qs like these its like more EQULIBRIUM my teacher is like its not that hard how much ure making it
MaNa:
does anyone has MAY /JUNE 00 MARK SCHEME FOR p1
as well as paper 3 , ms of p3 if soo can u please send me on insane_mana@live.com
thankyouuuuuuuuuuuuuuuu
Enia:
hi. I was wondering does anyone have any good notes on salt preparation? Or can you please explain it to me? (all the methods and such) Also..this is going to sound really stupid but can anyone be bothered to put together a list of compounds and their colours (the one's required?) I have a couple of them but I'm not sure if they're a)needed and b) correct.
Thank you. Oh and if it helps I'll post the list of the colours I DO know so you can just tell me the one's I'm missing out or the ones which I've got wrong.
Here it is:
1. CuCO3 ===>Green
2. CuO ===> Black
3. CuSO4 ===>White
4. CuSO4.5H2O ===> Blue
5. CoCl2.6H2O ===> Pink
6. CoCl2 ===> Blue
7. MnO2 ===> Shiny Black
8. KMnO4 ===> Purple
9. K2Cr2O7 ===> Orange
10. CuCl2 ===> Blue
Again, Thank you help will be much appreciated. ^^
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