Few Question GC from 2009Destroyer

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bluesolic

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I have few question from 2009 destroyer.


q 7.

why are ClF5 AND PBr5 Polar ??


q8 what's wrong ? question

the answer is all molecules of an ideal gas have the same kinetic energy at constant temperature..

isn't that sentence right ?

chad said that at constant temperature, the kinetic energy is the same but the velocity is going to be different due to the mass difference.


what's the meaning difference btwn

" all molecules of an ideal gas have the same kinetic energy at constant temperature " and " the average kinetic energy of a gas is proportional to the absolute temperature "

these sentences have same meaning right ??



question 16

consider a 15g sample of butane (c4h10) how many carbon atomes are contained in this sample.

I looked up the solution and it didn't make any sense to me..

molecules = is the quantity of bonds between atoms right ?

example ) c4h10 = 14 molecules


the answer is so strange and I never understood what the heck it is.. and Chad never explained this thing either and I was so confused...

15gc4h10 divided by 58gc4h10

so I have mole of butane...

the answer did times by 6x10^23 molecules c4h10/1mole c4h10..

here... 6x10^23 is atom numbers right? number of molecules of c4h10 is 14 here not 6x10^23...


I don't know please explain...


I just started doing destroyer and it made me so sad yesterday....


is there any differences btwn 2009 destroyer and 2011 ?
 
ClFl5 is polar because of electron pair on chlorine. Best way to do these problems is to draw out the complete lewis diagram with halogens (side groups) its easy to assign because they have 7 electrons so you know they'll have 3 lone pairs and one bond to the central atom.

15/58 = 0.25 mol of butane

0.25 mol butane * 4 mol C / mol butane = 1 mol C

1 mol carbon * 6*10^23 atoms/mol = 6*10^23 atoms.
 
I have few question from 2009 destroyer.


q 7.

why are ClF5 AND PBr5 Polar ??


q8 what's wrong ? question

the answer is all molecules of an ideal gas have the same kinetic energy at constant temperature..

isn't that sentence right ?

chad said that at constant temperature, the kinetic energy is the same but the velocity is going to be different due to the mass difference.


what's the meaning difference btwn

" all molecules of an ideal gas have the same kinetic energy at constant temperature " and " the average kinetic energy of a gas is proportional to the absolute temperature "

these sentences have same meaning right ??



question 16

consider a 15g sample of butane (c4h10) how many carbon atomes are contained in this sample.

I looked up the solution and it didn't make any sense to me..

molecules = is the quantity of bonds between atoms right ?

example ) c4h10 = 14 molecules


the answer is so strange and I never understood what the heck it is.. and Chad never explained this thing either and I was so confused...

15gc4h10 divided by 58gc4h10

so I have mole of butane...

the answer did times by 6x10^23 molecules c4h10/1mole c4h10..

here... 6x10^23 is atom numbers right? number of molecules of c4h10 is 14 here not 6x10^23...


I don't know please explain...


I just started doing destroyer and it made me so sad yesterday....


is there any differences btwn 2009 destroyer and 2011 ?

Not all molecules have the same kinetic energy at the same temperature. They possess the same "average" kinetic energy.
 
Erm let me go over the butane problem a little more in detail since you seem to have some concepts confused. Molecules generally refers to the compound. In this case you would 0.25 * 6*10^23 = 1.5 * 10 ^23 molecules of butene. Avogardo's number is the number of atoms/molecules per mol of substance.

The problem is asking you for the number of carbon of atoms. You know there is 4 carbon atoms per molecule, or 4 moles of carbon per mole of butene. Given 0.25 mol of butene, you have 1 mol of carbon using the above calculation simply multiply by Avogardo to get the number of carbon atoms

Or if you want you can calculate the number of molecules of butene first and then multiplying by 4 to get the atoms of carbon. Either way it gets you the same answer.
 
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