Subject: Why does grease does not disolve in water?

Yes, grease doesn't disolve in water but why? I'd like a good 
explaination for what's happening chemically. Also, why does 
detergent, when added to the water, disolve the grease? Again, what 
happens chemically?
I have another question which is about moles. (eg. 1 mole of K2CO3 
will be: 39(K) x 2 + 12(C) + 16(O)x 3= 138g for 1 mole)  I hope you 
see what I'm talking about, but you should know if you're scientists.
Well, my question is:  How many grams of NaOH is needed to make a 0.5 
dm3(cube) of a 0.5 molar solution? 
I know already that NaOH mass is 40 grams for 1 mole so you have to 
multiply by 0.5 'cause it says it's a 0.5 molar solution. But What do 
I do to calculate how much I need for 0.5 dm3 (cube) or half a litre.
I'd be very greatful if you could answer some of my question.
Thibaut

Re: Why does grease does not disolve in water?