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# Kc Problem, A2 Chemistry Help! Watch

1. hELP!

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2. Im hazarding a guess at 1.6mol dm-3 ?
3. (Original post by RagaZ)
hELP!

The first step is to work out how many moles of each substance you have. You know that half of the N2O4 has turned into NO2 so how many moles of NO2 will you have? Be careful, look at the equation.
4. (Original post by Chlorophile)
The first step is to work out how many moles of each substance you have. You know that half of the N2O4 has turned into NO2 so how many moles of NO2 will you have? Be careful, look at the equation.
Hey so this is what I thought, I'm not sure if I worked out the number of moles correctly though

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5. (Original post by RagaZ)
Hey so this is what I thought, I'm not sure if I worked out the number of moles correctly though

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We're definitely not going to have 1 mol of N2O4, half of it has dissociated! First work out how many moles of N2O4 you've lost, then work out how many moles of NO2 can be created from that.
6. (Original post by Chlorophile)
We're definitely not going to have 1 mol of N2O4, half of it has dissociated! First work out how many moles of N2O4 you've lost, then work out how many moles of NO2 can be created from that.
im literally getting nowhere :/ but let me try...
right so if we've started with 1mol of N2O4, then 50% dissociates, 0.5mols of N2O4 would be left correct?
the stoichiometry is 1:2, so i presume the number of moles would be 1mol of NO2 formed
7. (Original post by RagaZ)
im literally getting nowhere :/ but let me try...
right so if we've started with 1mol of N2O4, then 50% dissociates, 0.5mols of N2O4 would be left correct?
the stoichiometry is 1:2, so i presume the number of moles would be 1mol of NO2 formed
Completely correct! Now just work out the respective concentrations, put them into the formula and you're done.
8. (Original post by Chlorophile)
Completely correct! Now just work out the respective concentrations, put them into the formula and you're done.
halleluja! thanks so much Chlorophile!

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