Need help with a Kc question

2g of hydrogen gas is introduced into a 1dm3vessel containing 25.4g of solid iodine.The vessel is sealed and heated to vaporise the iodine. At equilibrium the concentration of iodine vapour is found to be 0.09moldm-3 . Find Kc for the reaction. Assume the volume of the vessel remains 1dm3.

H2(g) + I2(g) 2HI(g)

I found the mole of I2 and H2 but how do I find the conc of H2?
For the mole of HI, I got 0.1007 correct?

Thanks

Reply 1

MexicanKeith

12

Original post by coconut64

2g of hydrogen gas is introduced into a 1dm3vessel containing 25.4g of solid iodine.The vessel is sealed and heated to vaporise the iodine. At equilibrium the concentration of iodine vapour is found to be 0.09moldm-3 . Find Kc for the reaction. Assume the volume of the vessel remains 1dm3.

H2(g) + I2(g) 2HI(g)

I found the mole of I2 and H2 but how do I find the conc of H2?
For the mole of HI, I got 0.1007 correct?

Thanks

First, what are the initial moles and concentrations of H2 and I2?

Reply 2

coconut64

OP

16

Original post by MexicanKeith

First, what are the initial moles and concentrations of H2 and I2?

Initial mole of H2 is just 1 and I2 is 0.1007. So I said that n of HI will be 0.201
Thanks

Reply 3

Pinkberry_y

19

I read Kc as KFC, my bad

Reply 4

MexicanKeith

12

Original post by coconut64

Initial mole of H2 is just 1 and I2 is 0.1007. So I said that n of HI will be 0.201
Thanks

Yeah, its pretty reasonable to just say 1 mole H2 and 0.1 mole I2

That amount of HI would be correct if the reaction produced the maximum possible amount of product, but instead its in equilibrium!

0.09 moles of I2 left at equilibrium, so 0.01 moles have actually reacted to form HI.

From that, you can work out how much H2 is left and how much HI is produced! :biggrin:

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