What are some methods for separating mixtures in chemistry?

[danago]

Hey. For my chemistry exam coming up soon, i was told to study these long answer questions. Could someone please help me out with them.


Discuss the differences between an ideal gas and a real gas in terms of the assumptions of the kinetic theory.


Well to start with, id state the six assumptions:

1. Gases consist of tiny particles called molecules, with the exception of noble gases, which consist of single atoms
2. The average distance between particles in a gas is very large, in comparison to the size of the particles
3. The molecules of a gas move in rapid random straight line motions. These movements result in collisions with other particles and container walls
4. The forces of attraction/repulsion between the particles are negligible
5. Collisions are perfectly elastic, meaning no net energy loss occurs during collisions
6. The average kinetic energy of the molecules of a gas increase with temperature

What should i do from there? Heres a few ideas I've thought of, in note form:

• Gas particles have a volume, although quite small, so there are forces of attraction/repulsion

And well yea...thats all i can think of at the moment

Describe in detail the best methods for the separation of the following mixtures. Include a discussion on why the method works.
a) Sand and sugar in water
b) Iron filings and copper sulfate

For the sand and water mixture, to start with, id look at the sand. Since it is insolube in water, id either decant or filter it. If it is a heavy sand, id decant, otherwise, id filter.

Once that's complete, and i have separated the sugar water from the sand, id evaporate the water from the sugar solution. Since the sugar and water have very different boiling points, (the water being lower), i could fully evaporate the water and be left with sugar.

For the copper sulfate and iron filings, what i would have said is to add water to the mixture, to dissolve the copper sulfate. Id then decant the mixture to remove any iron filings. Then heat the copper sulfate solution to rid of any water.





Thats all for now. Please tell me any other information i could include.

Thanks,
Dan.

 

[Hootenanny]

For your ideal gasses a good thread is located https://www.physicsforums.com/showthread.php?t=121779".

As for seperating the mixtures your answers are fine. However, it may be better to state that you will use distilled water, this negates the requirement for purification of the separated products. An easier method for seperating the iron fillings would be to use a magnet

~H

 

[danago]

ok thanks :)

One more thing. Could you explain what it means for the collisions to be perfectly elastic? Does it mean that as a particle collides with another, there is no energy transferred?

 

[Hootenanny]

It means kinetic energy is conserved.

~H

 

[danago]

So there is never going to be heat lost to the container through collisions in an ideal gas?

 

[Gokul43201]

That's correct.

 

[Hootenanny]

So there is never going to be heat lost to the container through collisions in an ideal gas?

You are correct. Damn Gokul types fast!

~H

 

[danago]

ok thanks :)