Define Organic Compounds As Polar Or Nonpolar

[fishes]

1.Which of the following compounds are nonpolar?

1) decene

2) decanal

3) 3-methyl-2-decene

4) 1,2-pentanediol

5) cyclohexanol

Select one:
a. 1,2 and 3 only
b. 1 and 2 only
c. 3,4 and 5 only
d. 1,2,3 and 5 only
e. 1 and 3 only

2. Which of the following compounds are polar?

1) 2-butyne

2) propanal

3) propanamide

4) 3-aminopentane

5) 3-heptene

Select one:
a. 2, 3 and 5 only
b. 1, 3 and 5 only
c. 3,4 and 5 only
d. 1,2,4 and 5 only
e. 2, 3 and 4 only

The Attempt at a Solution

[/B]
1. For this question I'm tossing up between a and d. I'm pretty confident on 1, 2 and 3 because they are hydrocarbons without any functional groups that can donate protons. I know cyclohexanol has a OH functional group which is very polar but the fact that it's not soluble in water is throwing me off. I would probably go with A at the moment.

2. For this one I'm going with E as 5 is an alkene without any functional groups which means it is nonpolar. This cancels out A-D.

Thanks for the help!

 

[Borek]

I'm pretty confident on 1, 2 and 3 because they are hydrocarbons without any functional groups that can donate protons

You don't need a group donating protons for molecule to be polar. Chloromethane is polar.

 

[fishes]

You don't need a group donating protons for molecule to be polar. Chloromethane is polar.

Good to know! I don't think that changes any of my answers though so were they right?

 

[Borek]

I don't think that changes any of my answers

It does ;)

Analyze the first question again.

 

[fishes]

Does that mean cyclohexanol isn't polar so the answer would be 1.D and 2.E ? Thanks for all the help by the way!

 

[Borek]

No, cyclohexanol is polar (all alcohols are, just like products of their oxidation).

 

[fishes]

Well if A and D are wrong for 1 I assume it's between B and E? In that case I would go with E as aldehydes are a lot more polar than alkenes?

 

[Borek]

E would be my answer.

 

[fishes]

Sounds good but I thought that aldehydes were considered to be pretty nonpolar which would mean decanal would be nonpolar as well as its the simplest 10 carbon aldehyde?

 

[Borek]

They are definitely more polar than hydrocarbons. Carbonyl itself is quite polar.