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# Equilibrium quantities initial moles to equilibrium moles.... watch

1. Im really stuck on how to calculate equilibrium moles from initial moles

eg. CH4 + H20 (REVERSIBLE REACTION SIGN) CO + 3H2
INITIAL MOLES 1 1 0 0
EQUILIRIUM MOLES 0.4

ANY HELP MUCH APPRECIATED
2. (Original post by rumana101)
Im really stuck on how to calculate equilibrium moles from initial moles

eg. CH4 + H20 (REVERSIBLE REACTION SIGN) CO + 3H2
INITIAL MOLES 1 1 0 0
EQUILIRIUM MOLES 0.4

ANY HELP MUCH APPRECIATED
THIS IS SO EASY WHEN YOU KNOW HOW. PPL TAUGHT ME NOW I SHALL HELP YOU (hopefully i get it right)

so equilib moles of CH4 is 0.4
thus 0.6 moles has been used

see the equation tells you 1 mol of CH4 reacts with 1 mol of H2O?
that means H2O must also have gone down by the same amount of moles. which is 0.6

so far equilib moles of CH4 is 0.4 and H2O is 0.4 moles too

where does the 0.6 moles go? good question
the go on the other side.
so you get 0.6 mol of CO NOW BE CAREFUL

the equation tells us 1 mol of CH4 reacts with 1 mol of H2O to form 1 mol of CO and 3 mol of H2

so multiply 0.6 by 3 and you have 1.8 mol of H2

i think this is right
CH4 H2O CO 3H2
equilib moles 0.4 0.4 0.6 1.8

that's right the moles don't have to add up
3. I kind of get it please could you explain the steps for this past paper question

The reaction of methane with steam produces hydrogen for use in many industrialprocesses. Under certain conditions the following reaction occurs. CH4(g) + 2H2O(g) CO2(g) + 4H2(g) ∆H = +165 kJ mol–1 Initially, 1.0 mol of methane and 2.0 mol of steam were placed in a flask and heatedwith a catalyst until equilibrium was established. The equilibrium mixture contained0.25 mol of carbon dioxide. Calculate the amounts, in moles, of methane, steam and hydrogen in the equilibriummixture. Moles of methane ................................ ................................ ................................ ............. Moles of steam ................................ ................................ ................................ .................. Moles of hydrogen ................................ ................................ ................................ .............
4. (Original post by rumana101)
I kind of get it please could you explain the steps for this past paper question

The reaction of methane with steam produces hydrogen for use in many industrial processes. Under certain conditions the following reaction occurs.
CH4(g) + 2H2O(g) CO2(g) + 4H2(g) ∆H = +165 kJ mol–1 Initially, 1.0 mol of methane and 2.0 mol of steam were placed in a flask and heated with a catalyst until equilibrium was established.
The equilibrium mixture contained 0.25 mol of carbon dioxide. Calculate the amounts, in moles, of methane, steam and hydrogen in the equilibrium mixture. Moles of methane ................................ ................................ ................................ ............. Moles of steam ................................ ................................ ................................ .................. Moles of hydrogen ................................ ................................ ................................ .............
ok
CH4 2H2O CO2 4H2
So initial moles 1 2 0 0
equilib moles 0.25

you know that CH4 reacts with 2H2O to produce 1 mol of CO2 and 4 mol of 4H2
if 0.25 mol of CO2 was produced then 4 x 0.25 mol of H2 was produced yes?

equilib moles 0.25 1

now here's the slightly more difficult bit
you see 0.25 of CO2 was produced when 1 mol of CH4 and 2 mol of H2O reacted?

This means that 1-0.25 is the mol of CH4 left after it has reacted with H2O to form 0.25 mol of CO2

equilib moles 0.75 0.25 1

so we know 1 mol of CH4 reacts with 2 mol of H2O so
0.75 x 2 =1.5 mol of H2O

equilib moles 0.75 1.5 0.25 1

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