Chemistry: Post your doubts here!

[Metanoia]

You are referring to the line

mole of H2 formed = 33.3/100 *2 ?

The 2 is the total moles of gases, moles of H2 = % of H2 x total moles

 

[princess Anu]

You are referring to the line

mole of H2 formed = 33.3/100 *2 ?

The 2 is the total moles of gases, moles of H2 = % of H2 x total moles

How do we know 2 moles of gas are present at Equilibrium?

 

[Metanoia]

..

Leaving mathematical calculations aside, we can reason it out in this manner.

A <-> B exothermic can also be represented by A <-> B + heat

A <-> B endothermic can also be represented by A + heat <-> B

Changing the temperature (removing or adding heat) will shift the equilibriums above.

Only equilibriums that are neither exothermic nor endothermic will not shift during temperature changes.
In other words, the enthalpy change of such reactions is zero (heat is neither a "reactant" nor a "product".)

 

[Metanoia]

How do we know 2 moles of gas are present at Equilibrium?

total moles = 1- x + 1 -x + x + x = 2 moles

 

[princess Anu]

total moles = 1- x + 1 -x + x + x = 2 moles

thanks a lot

 

[princess Anu]

..

 

[Metanoia]

..

The NH3 molecule is the same before and after the reaction, so we would not expect any change in its oxidation state.

Ag+ + 2NH3 --> [Ag(NH3)2]+

If you do intend to calculate each atoms, you have to be careful.
+1 + 2x + 6 = +1 ( you had -2x instead of +2x)

 

[princess Anu]

which ones are the intermediate for each??

 

[princess Anu]

.

 

[Mahnoorfatima]

http://www.sheir.org/a-level-chemistry-11-june2011.pdf
In q 40, how can X be ethanoic acid? The emperical formula is C4 whereas ethanoic has 2 C only??

 

[Mahnoorfatima]

http://www.sheir.org/a-level-chemistry-13-nov2011.pdf
Q 14 and 15 and 25 anyone?

 

[Xaptor16]

In aqueous solution, the acid HIO disproportionates according to the following equation where m,
n, p and q are simple whole numbers in their lowest ratios.
mHIO → nI2 + pHIO3 + qH2O
This equation can be balanced using oxidation numbers.
What are the values for n and p?
n p
a) 1 2
b) 2 1
c) 4 1
d) 4 2

the answer is B
I know how to figure out the oxidation numbers, but I need explanation on how to balance such equations using oxidation numbers... help please!!

 

[princess Anu]

http://www.sheir.org/a-level-chemistry-13-nov2011.pdf
Q 14 and 15 and 25 anyone?

check my answers first
14B
15B
25D??

 

[Mahnoorfatima]

check my answers first
14B
15B
25D??

25 is C rest are correct. Can you please explain?

 

[princess Anu]

25 is C rest are correct. Can you please explain?

 

[princess Anu]

25 is C rest are correct. Can you please explain?

 

[Mahnoorfatima]

Why the division by a million? :/

 

[princess Anu]

25 is C rest are correct. Can you please explain?

Q25

 

[princess Anu]

Why the division by a million? :/

I have divided the Mr in grams by 1000000000000 because I tonne contains 1oooooo g and the question mentions million tonnes..

 

[Mahnoorfatima]

I have divided the Mr in grams by 1000000000000 because I tonne contains 1oooooo g and the question mentions million tonnes..

TYSM!