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### Topic: volume and moles  (Read 9303 times)

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#### NISHANT

• Guest
##### volume and moles
« on: January 03, 2005, 11:07:36 AM »
Q:60 ml of H2 nd 42ml of I2 are heated in a closed vessel.At eq. the vessel contains 28ml of HI.Calculate the degree of dissociation of HI.

here nowhere is it written that pressure is constant during the reaction,therefore is it right to consider volume of the substances proportional to their moles and use the volumes of the given substances in the same way as we would have used the moles??

#### Demotivator

• Guest
##### Re:volume and moles
« Reply #1 on: January 03, 2005, 11:22:56 AM »
yes, assuming ideal behavior.

#### NISHANT

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##### Re:volume and moles
« Reply #2 on: January 03, 2005, 11:27:11 AM »
YES OR NO?
I DID NOT UNDERSTAND.
IF YES THEN IF THE PRSSURE OF ANY SUBSTANCE IS CHANGING HOW CAN THE VOLUME BE PROPORTIONAL TO MOLES?

#### Demotivator

• Guest
##### Re:volume and moles
« Reply #3 on: January 03, 2005, 12:37:11 PM »
Those volumes are proprtional to moles according to the law of combining volumes for gases, provided the volumes are measured at fixed temp and pressure for all gases. I assume 60 ml, etc are a measure of a gas as virtually isolated outside the vessel (ie in a measuring vessel at fixed pressure). Otherwise, how can it be, since a gas's actual volume is the volume of the reaction vessel itself?

H2 + I2 -> 2HI
Equal moles of HI produced for reactants consumed.
Therefore, The total pressure in the reaction vessel is constant and individual pressures are proportional to moles (Dalton's law of partial pressures).
Of course, the pressure can vary if the temperature is different but it affects all components the same way.

#### Donaldson Tan

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##### Re:volume and moles
« Reply #4 on: January 03, 2005, 08:43:04 PM »
i agree with demotivator
"Say you're in a [chemical] plant and there's a snake on the floor. What are you going to do? Call a consultant? Get a meeting together to talk about which color is the snake? Employees should do one thing: walk over there and you step on the friggin� snake." - Jean-Pierre Garnier, CEO of Glaxosmithkline, June 2006