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Offline dillonchester21

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chem homework problem
« on: November 17, 2015, 02:54:23 PM »
I have to describe what will happen in terms of kinetic energy. Are these fine?

1) Volume doubles, temperature constant
Since not talking about average kinetic energy i think it means a decrease in kinetic energy due to less collisions.

2) Temperature increase
increase in kinetic energy due to more collisions.

3) Absolute Zero
Molecules are still moving, thus there is a minimal amount of kinetic energy.

Offline Enthalpy

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Re: chem homework problem
« Reply #1 on: November 17, 2015, 03:16:51 PM »
Ouch no. The kinetic energy relates with the speed of the molecules.

Offline dillonchester21

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Re: chem homework problem
« Reply #2 on: November 17, 2015, 03:37:53 PM »
What do you mean? How are these wrong?

so is 1) the kinetic energy is the same
2) kinetic energy increases
3) molecules are not still, they are moving at minimal kinetic energy

Online Borek

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Re: chem homework problem
« Reply #3 on: November 18, 2015, 03:22:16 AM »
What do you mean? How are these wrong?

Number of collisions doesn't matter at all. More collisions doesn't mean higher energy. Single molecule doesn't collied with anything, it doesn't mean its energy is zero.

Quote
so is 1) the kinetic energy is the same
2) kinetic energy increases

Yes. Kinetic energy of a molecule is directly proportional to the temperature (so increasing the absolute temperature twice means increasing the average energy of molecules twice).

Quote
3) molecules are not still, they are moving at minimal kinetic energy

This is tricky. At absolute temperature zero they stop moving, although - due to the Heisenberg uncertainty principle - they still oscillate slightly in place.
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