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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: 113zami on June 11, 2008, 06:19:48 PM

Title: what's the advantage of soxhlet extractor?which molecules can form dimers?
Post by: 113zami on June 11, 2008, 06:19:48 PM
I am so sorry I had multiple questions, I am new to the forum so i didn't know if I should have 1post per question or can I put multiple questions per post


1)What's the advantage of soxhlet extractor? I read up on it and understand it's function but don't understand what's the advantage


2) which one has higher melting point ionic bond or network covalent bond?
I know that both have very hi melting point but which one is higher???

3) considering the following elementary steps, which one would be the least likely to occure?

a) 2X+2Y---->W+Z
b) 2X+Y-----> 2W+Z

the correct answer is A) and in the explanation it says the more reactants involved the less likely for a fruitiful collision therefore the first reaction is the correct answer, but I read up on the collision theory and it says the more the concentrated the reactants the more collisions, wouldn't higher reactant coefficient values indicate more concentrations(assuming that the volumes are the same)?
so I think b) should be less likely to occur since it has less reactant concentrations and I don't understand why A is correct

4)which molecule is likely to form dimers?

a)BF3
b)NO2-
c)NO2
d)NO2+

the correct answer is  C   , C is a radicle and I can uderstand why it would form dimers but why wouldn't the other choices be able to form dimers?, to my knowledge any 2 molecules can form dimers there isn't really a restriction to forming dimers



thanks for the help

Title: Re: what's the advantage of soxhlet extractor?which molecules can form dimers?
Post by: macman104 on June 11, 2008, 07:28:23 PM
1)What's the advantage of soxhlet extractor? I read up on it and understand it's function but don't understand what's the advantage
The advantage is that instead of using multiple portions of solvent to dissolve your compound, you can reuse the same portion of solvent over and over.  The wikipedia article walks you step-by-step how the process works, and the advantages of it.
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2) which one has higher melting point ionic bond or network covalent bond?
I know that both have very hi melting point but which one is higher???
I would imagine it would depend on the two items being compared.  Can you give a more concrete example.
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3) considering the following elementary steps, which one would be the least likely to occure?

a) 2X+2Y---->W+Z
b) 2X+Y-----> 2W+Z

the correct answer is A) and in the explanation it says the more reactants involved the less likely for a fruitiful collision therefore the first reaction is the correct answer, but I read up on the collision theory and it says the more the concentrated the reactants the more collisions, wouldn't higher reactant coefficient values indicate more concentrations(assuming that the volumes are the same)?
so I think b) should be less likely to occur since it has less reactant concentrations and I don't understand why A is correct
What they are trying to say is that for reaction a to occur, FOUR separate items must collide all at the same time for the reaction to occur.  Whereas in the second reaction only THREE items must collide to make the reaction occur.  It is true that if you increase the concentrations, then the collisions will be more likely to occur, but that is also true of the second reaction.  The point of the question is that the first collision circumstance is less likely than the second

Also, I'm not exactly sure about the last question, sorry.
Title: Re: what's the advantage of soxhlet extractor?which molecules can form dimers?
Post by: Borek on June 12, 2008, 03:38:49 AM
i didn't know if I should have 1post per question or can I put multiple questions per post

Better several question together, but keep them to minimum. Do what you know first, ask about those reamaining only.

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2) which one has higher melting point ionic bond or network covalent bond?
I know that both have very hi melting point but which one is higher???

What is melting point of NaCl? What is melting point of SO2?