alkane and alkene

1.Why viscosity of alkanes increases with the number of carbon atoms contained?

2.Members in the same homologous series have the same functional group,but why they only have similar chemical properties but not the same?

3.Why alkane has no functional group?

4.In organic compound, wt's the meaning of saturated?
If an organic compound contains N=N or nitrogen nitrogen triple bond,then is this compound saturated?(provided that this compound has C-C only)

5.In alkenes, Can C=C appeared twice?

6.What is the colour of alkanes?In fractional distillation od petroleum, the products produced are colourless,yellow and even brown.But in book,it says that alkanes are colourless and white.Why?

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[i]1.Why viscosity of alkanes increases with the number of carbon atoms contained?[/i]

Well, what do you think causes viscosity? Could it be something to do with how strongly the molecules stick together? What makes molecules stick together?

[i]2.Members in the same homologous series have the same functional group,but why they only have similar chemical properties but not the same?[/i]

Because they are different molecules! :lol: That's like asking "I have two brothers that like most of the same food for dinner as me, but why don't we like EXACTLY the same things?"

[i]3.Why alkane has no functional group?[/i]

This is tautological! :-) "alkane" is the word people decided to use to name hydrocarbon molecules that had no functional group!

[i]
4.In organic compound, wt's the meaning of saturated?
If an organic compound contains N=N or nitrogen nitrogen triple bond,then is this compound saturated?(provided that this compound has C-C only)[/i]

Mmmm, usually people mean Carbon double and triple bonds when they talk about "unsaturated"

[i]
5.In alkenes, Can C=C appeared twice?[/i]

Yes, why not! :-) If the C=C=C bonds are beside each other, it's called an "allene"

[i]6.What is the colour of alkanes?In fractional distillation od petroleum, the products produced are colourless,yellow and even brown.But in book,it says that alkanes are colourless and white.Why?[/i]

What book is this? Who wrote it? Perhaps they were blind. Or just trying to trick you ;-)

6. most simple alkanes are colorless.

[quote="feline1"][i]
1.Why viscosity of alkanes increases with the number of carbon atoms contained?[/i]

Well, what do you think causes viscosity? Could it be something to do with how strongly the molecules stick together? What makes molecules stick together?

[color=red]If the Vander Waal's force between the molecules is strong, it means the substance is more viscous?[/color]

[i]2.Members in the same homologous series have the same functional group,but why they only have similar chemical properties but not the same?[/i]

Because they are different molecules! :lol: That's like asking "I have two brothers that like most of the same food for dinner as me, but why don't we like EXACTLY the same things?"
[color=red]Then can u tell me wt's the difference between the chmical and physical properties between isomers also?And also the physical properties of compound in the same homologus series?[/color]
[i]3.Why alkane has no functional group?[/i]

This is tautological! :-) "alkane" is the word people decided to use to name hydrocarbon molecules that had no functional group!

[color=red]Why -C-H isn't the functional group of alkane?[/color]

[/quote]

Different geometrical isomers may well have different physical properties because of things like the way their dipoles are aligned (or opposed)

This may also make their chemical reactivity different, as leaving groups are in a better position to jump off, etc etc

Enantiomers are the same except for the way they rotate polarized light, and the way they react with other chiral molecules.

The bigger a molecule, the more Van der Waals forces it'll be subject too.... so as you go along a homologous series, you'll see the effects of this.....

As for "C-H" being a functional group -
well this is just nomenclature, not chemistry!

The phrase "functional group" generally means "this bit of the molecule that does the interesting stuff, like participate in chemical reactions" - the rest of the molecule doesn't do much.....

....so in an alkane, there's no one "C-H" bond which is doing all the interesting stuff - they're just all the same - so the concept of a "functional group" doesn't really make much sense here.

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