Chem question (1 Viewer)

[riya03]

Could someone plz explain how to find the molecular formula from the question -

0.015 mol of a hydrocarbon has a mass of 0.063 g. calculate the molar weight of hydrocarbon and suggest a possible molecular formula for the hydrocarbon.

the molar weight is 42 g/mol, but how do i find the molecular formula?

 

[mathemalia]

hey,

the only thing i could think off at the moment is that carbon has an atomic number of 6 and hence has 4 electrons in its valence shell. So it needs to gain 4 more. Since the other reactant is hydrogen (hydro) then the empirical formula should be something like

CH_4 (the 4 is the subscript)...and thats in fact the actual molecular formula for hydrocarbon...


hope that helps

-mathemalia

 

[carmot]

The molar weight is basically all the atomic masses of the formula added together. So some combination of carbon (12) and hydrogen (1) added together will give you 42 e.g. 3x12 + 6x1 = 42, or C3H6

 

[philtration]

if you dnt understand the concept of something go to Khan Academy i assure u its a useful link. teaches u chem, phy, bio (Y)

 

[Entrant]

if you dnt understand the concept of something go to Khan Academy i assure u its a useful link. teaches u chem, phy, bio (Y)

and maths.

 

[Julie Y]

if you dnt understand the concept of something go to Khan Academy i assure u its a useful link. teaches u chem, phy, bio (Y)

cool site
(=

 

[hscishard]

Bump.

I don't get it. Why do I get 4.2g

 

[freezeice04]

Bump.

I don't get it. Why do I get 4.2g

I get 4.2g as well. The question is wrong I think.

 

[silence--]

possible that the mass was supposed to be 0.63, instead of 0.063. then 0.63/0.015 = 42.

definitely can't have a molar mass of 4.2g =P

 

[ibbi00]

We addressed this question in a different thread. And yes answer is 4.2g. BOB was wrong.