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Regarding drawing structural isomers + 1 Metal Question (1 Viewer)

erika5d

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Hi guys,

I'm having trouble with drawing the structural formulae of structural isomers. For example, I don't understand why is there only two isomers can be drawn from C3H7Cl (1-cholropropane and 2-chloropropane)? Can't it be 3-chloropropane? Or the following?
Screen Shot 2013-04-14 at 6.27.34 PM.jpg

Also, for this question (b), the product should contains hydrogen gas, doesn't it? However I don't think there is any hydrogen atoms among the reactants...
Scan.jpg

Any help would be appreciated!!
 

HeroicPandas

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Say if u draw the compound out like this:

--Cl-H-H
H-C-C-C-H
--H-H-H

To know if we name from right to left or left to right - we say: which side has the substituent? (LEFT), therefore we name from the LEFT to RIGHT

Hence, 1-chloropropane

But if we name from the right to left, it would be wrong because we want the LOWEST numbers (and in alphabetical order)

The next one............

the question says: "Write a balanced equation for the reaction producing the gas"

Cant u just write any equation producing hydrogen gas? metal + acid -> salt + H2 (g)
 

erika5d

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Sorry I didn't express myself correctly. For the first one I meant how do you draw C3H7Cl instead of how to name the answers: 1-cholropropane and 2-chloropropane :p
So the question is asking me to draw C3H7Cl, and the answers given were 1-cholropropane:
Screen Shot 2013-04-14 at 10.14.38 PM.jpg
and 2-chloropropane:
Screen Shot 2013-04-14 at 10.15.08 PM.jpg

but what I've drawn was this (3-chloropropane?):
Screen Shot 2013-04-14 at 10.15.22 PM.jpg

I don't get why what I've drawn, or even the followings, are not part of the right answers.
Screen Shot 2013-04-14 at 10.15.35 PM.jpg
Screen Shot 2013-04-14 at 10.15.49 PM.jpg
Screen Shot 2013-04-14 at 10.15.59 PM.jpg

And thanks for the second question! lol what was I thinking!
 

HeroicPandas

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Sorry I didn't express myself correctly. For the first one I meant how do you draw C3H7Cl instead of how to name the answers: 1-cholropropane and 2-chloropropane :p
So the question is asking me to draw C3H7Cl, and the answers given were 1-cholropropane:
View attachment 27984......A
and 2-chloropropane:
View attachment 27985...........B

but what I've drawn was this (3-chloropropane?):
View attachment 27986.........C

I don't get why what I've drawn, or even the followings, are not part of the right answers.
View attachment 27987........D
View attachment 27988.........E
View attachment 27989..........F

And thanks for the second question! lol what was I thinking!
A - ok
B - ok
C - incorrect, that is not 3-chloropropane, dread my post b4, i explained to u how to name compounds
D, E, F - define isomer: "Each of two or more compounds with the same formula but a different arrangement of atoms in the molecule and different properties." They are ALL correct, the Cl atom can up or down, doesnt matter if its top or bottom. A and D are both 1-chloropropane (if i draw A and u draw D, we get the same marks)

please let me know if i am incorrect!
 

Parvee

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For the 1-chloropropane and 3-chloropropane they are exactly the same structuce but for naming 1-chloropropane is correct

Think of it this way
When you draw 1-chloropropane and you turn the whole structure by 180 degrees you will get 3-chloropropane, hence they are the same so you dont need to write them as seperate isomers
 

erika5d

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A - ok
B - ok
C - incorrect, that is not 3-chloropropane, dread my post b4, i explained to u how to name compounds
D, E, F - define isomer: "Each of two or more compounds with the same formula but a different arrangement of atoms in the molecule and different properties." They are ALL correct, the Cl atom can up or down, doesnt matter if its top or bottom. A and D are both 1-chloropropane (if i draw A and u draw D, we get the same marks)

please let me know if i am incorrect!
For the 1-chloropropane and 3-chloropropane they are exactly the same structuce but for naming 1-chloropropane is correct

Think of it this way
When you draw 1-chloropropane and you turn the whole structure by 180 degrees you will get 3-chloropropane, hence they are the same so you dont need to write them as seperate isomers
Cool, I get it now!! Thank you so much guys, this question has been bothering me for so long lol
 

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