Author Topic: Edexcel CHEMISTRY DOUBTS!!!!  (Read 253942 times)

Offline Amii

  • SF Farseer
  • *******
  • Posts: 3849
  • Reputation: 65535
  • Gender: Female
Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #765 on: February 20, 2011, 07:47:20 pm »
Increase pressure - Equilibrium shifts to the side with less no. of gas molecules.

Decrease pressure - Equilibrium shifts to the sdie with more no. of gas molecules.

Examples -
2SO2 (g) + O2(g) ---->  2SO3 (g)
                        <----

Increasing the pressure will cause the equilibrium to shift to the side with less no. of gas molecules.
Right:Left
3:2

Less no. of gas moleulces on the left - so forward reaction (to the right) is favoured.More SO3 is formed.

H2 (g) +I2 (g) ---> 2HI(g)
                    <---

Whether you increase or drecrease the pressure the postition of the equilibrium will not be affected since the same no. of gas molecules on both the sides of the equation.

Warning again - But I already typed it so posting it  :)
« Last Edit: February 20, 2011, 07:52:14 pm by Amii »

By my sweeett nephew ;D

Offline Amii

  • SF Farseer
  • *******
  • Posts: 3849
  • Reputation: 65535
  • Gender: Female
Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #766 on: February 20, 2011, 07:50:22 pm »
Alright, thanks alot! :)
No problem  :D

Take care

By my sweeett nephew ;D

Offline SauD~

  • Chére
  • SF V.I.P
  • ********
  • Posts: 8629
  • Reputation: 65535
  • Gender: Male
  • ~ I wish my dream comes true ~
Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #767 on: February 20, 2011, 08:22:06 pm »
It will depend on the state of the product.And if the product is a gas - then the no. of molceules of the gas.Basically the no. of molcules of gas in each side of the equation.

If more no. of gas molcules on the right hand side - increasing the pressure will shift the equilibrium to the left as less no. of gas molcules.Opposite effect for decrease in pressure

If more no. of gas molcules on the left hand side - increasing the pressure will shift the equilibrium to the right. Opposite effect for decrease in pressure.

If both the sides of the equation have the same no. of gas molcules then position of the equilibrium is not affected by a change in pressure.

Suppose CH4.6H20(s) ----> CH4(g) + 6H2O (l)
                              <----  

Reducing the pressure for this reaction will cause the equilibrium to shift to the left.As 1 gas molceule present on the right hand side of the equation but none on the left hand side.

I hope it helps  :-[    
Warning  
LOL Saud posted before I could  :D
Thanks annie to be here :D

The problem is that i am in ig and used my brain from what ever i have studied... sorry man, can't be much help :(

Offline Amii

  • SF Farseer
  • *******
  • Posts: 3849
  • Reputation: 65535
  • Gender: Female
Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #768 on: February 20, 2011, 08:52:08 pm »
increasing pressure favors where less gaseous molecules are present.. remember this thing :)

it can be make out if you the reactant has more gas molecules and the product side has less molecules, the reaction will favor backward forward if increasing the pressure. :)
But if the reactant has less gas molecule compare to product side. increasing pressure will favor forwardbackward reaction :)

You wrote the opposite thing.  ;)

Thanks annie to be here :D

The problem is that i am in ig and used my brain from what ever i have studied... sorry man, can't be much help :(
Atleast you tried helping  :D
+rep  ;D

By my sweeett nephew ;D

Offline SauD~

  • Chére
  • SF V.I.P
  • ********
  • Posts: 8629
  • Reputation: 65535
  • Gender: Male
  • ~ I wish my dream comes true ~
Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #769 on: February 20, 2011, 08:57:34 pm »
You wrote the opposite thing.  ;)
Atleast you tried helping  :D
+rep  ;D
Oh!! Another silly mistake >:(

i hate when i do silly mistake, i took products as reactants and vice versa >:( :'( :'(

Offline Amii

  • SF Farseer
  • *******
  • Posts: 3849
  • Reputation: 65535
  • Gender: Female
Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #770 on: February 20, 2011, 09:04:02 pm »
Oh!! Another silly mistake >:(

i hate when i do silly mistake, i took products as reactants and vice versa >:( :'( :'(

Doesn't matter - you can always correct yourself  :D

By my sweeett nephew ;D

Offline Uchia

  • SF Citizen
  • ***
  • Posts: 171
  • Reputation: 379
Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #771 on: March 10, 2011, 11:00:57 am »
hey Amii

hello

i got my chem 4 result yesterday i scored perfect hamduila

thanks for ur help

116/120

Offline Amii

  • SF Farseer
  • *******
  • Posts: 3849
  • Reputation: 65535
  • Gender: Female
Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #772 on: March 10, 2011, 12:19:42 pm »
hey Amii

hello

i got my chem 4 result yesterday i scored perfect hamduila

thanks for ur help

116/120
Heeyy

Congratulations   ;D

It wasn't me.I just gave you some you sites for mass spectrometer once.You must be talking about Amelia  ;)

Take care :)
« Last Edit: March 10, 2011, 12:21:26 pm by Amii »

By my sweeett nephew ;D

Offline Uchia

  • SF Citizen
  • ***
  • Posts: 171
  • Reputation: 379
Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #773 on: March 10, 2011, 01:17:00 pm »
lool ur name and her are so close i thought that it is the same person
  ::)
but still i should thank u 2 cz there was a biq guestion about the mass spectro thingii in the exam

and

Amelia  ;D

 

Amelia

  • Guest
Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #774 on: March 10, 2011, 04:48:31 pm »
hey Amii

hello

i got my chem 4 result yesterday i scored perfect hamduila

thanks for ur help

116/120

You did good, mA.  :)



lool ur name and her are so close i thought that it is the same person
  ::)
but still i should thank u 2 cz there was a biq guestion about the mass spectro thingii in the exam

and

Amelia  ;D

Ahh.. that's sweet.  :)

Offline ~ Miss Relina ~

  • SF Senior Citizen
  • *****
  • Posts: 611
  • Reputation: 65535
  • Gender: Female
  • Every rose has a thorn
Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #775 on: March 11, 2011, 06:29:21 pm »
well my question is
 How many no.of atoms present in 1 gram of ice ???and why it have larger no.of atoms i than in 1 gram of daimond???
~~~Yarab everything turns alright at the end ~~~
    -----------Ameeeeeeeeeeen------------

Offline Amii

  • SF Farseer
  • *******
  • Posts: 3849
  • Reputation: 65535
  • Gender: Female
Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #776 on: March 11, 2011, 07:06:34 pm »
well my question is
 How many no.of atoms present in 1 gram of ice ???and why it have larger no.of atoms i than in 1 gram of daimond???
Okay I am really not sure of this but will just give it a try

Diamond is made of up carbon, so take the molar mass of this as 12 g mol -1

Number of moles =  Mass/Mr
                       = 1/12
                       = 0.083 moles

Number of atoms =  0.083* Avagodro's number
                       = 0.083 X 6.022*10 23
                       = 4.998 x 10 22 atoms

Ice means H2O

Molar mass = 2+16=18 g mol-1

Number of moles = 1/18=0.056 moles

Number of atoms = 0.056 X 6.022 *10 23
                       = 3.37 * 10 22  X 3 (Number of atoms in a water molecule )
                       =1.011 X 10 ^23

4.998 X 10^ 22 < 1.011x 10^ 23
Diamond < Ice

Take care  :D
« Last Edit: March 11, 2011, 07:20:22 pm by Amii »

By my sweeett nephew ;D

Offline ~ Miss Relina ~

  • SF Senior Citizen
  • *****
  • Posts: 611
  • Reputation: 65535
  • Gender: Female
  • Every rose has a thorn
Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #777 on: March 11, 2011, 08:51:52 pm »
Okay I am really not sure of this but will just give it a try

Diamond is made of up carbon, so take the molar mass of this as 12 g mol -1

Number of moles =  Mass/Mr
                       = 1/12
                       = 0.083 moles

Number of atoms =  0.083* Avagodro's number
                       = 0.083 X 6.022*10 23
                       = 4.998 x 10 22 atoms

Ice means H2O

Molar mass = 2+16=18 g mol-1

Number of moles = 1/18=0.056 moles

Number of atoms = 0.056 X 6.022 *10 23
                       = 3.37 * 10 22  X 3 (Number of atoms in a water molecule )
                       =1.011 X 10 ^23

4.998 X 10^ 22 < 1.011x 10^ 23
Diamond < Ice

Take care  :D

thnkx dear
~~~Yarab everything turns alright at the end ~~~
    -----------Ameeeeeeeeeeen------------

Offline Amii

  • SF Farseer
  • *******
  • Posts: 3849
  • Reputation: 65535
  • Gender: Female
Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #778 on: March 11, 2011, 08:56:39 pm »

By my sweeett nephew ;D

Offline ibuprofen500

  • Newbie
  • *
  • Posts: 15
  • Reputation: 160
  • Gender: Female
Re: Edexcel CHEMISTRY DOUBTS!!!!
« Reply #779 on: March 13, 2011, 07:24:00 pm »
Hi, I would like to know how to use the anti-clockwise rule to help me predict whether a reaction will occur.
 i hope someone can explain for me i tried to read about it alot but i cant seem to understand how the arrows help to predict whether a reaction will occur or no ): ?

here are examples :

Using the anti-clockwise rule:
( image attached down )

The reverse reaction is favored, so MnO2 and HCL will not react.


how did they figure out just by arrows that it will not react D: ???
« Last Edit: March 13, 2011, 08:11:20 pm by vicoden »