100%(benzene) = ???moles/dm^3 ?????? , Hive Newbee Forum

pink_dust_angel (Stranger)
06-08-04 17:48
No 512204

100%(benzene) = ???moles/dm^3 ??????

ok say swim has some 100% pure benzene, what is the molarity of this?
how does 1 work out the molarity of a pure substance knowing only the number of moles present?
swim only knows the following calcs:
Moles= mass(g)/molar mass
Moles= volume(dm^3) x moles/dm^3
this leaves swim with 2 unknowns (if swim only knows how many moles are present)

Rhodium
(Chief Bee)
06-08-04 18:30
No 512208

You need to look up the density and molar mass

Molarity = Moles/dm³
Density = Grams/dm³
Molar mass = Grams/Mole

Molarity = molar mass/density

^{The Hive - Clandestine Chemists Without Borders}

carbocation
(Stranger)
06-08-04 18:38
No 512210

calculations

okay, the relative molecular weight (M/R) of benzene= 78. Therefore 78g= 1 mole
A 1M benzene solution= 78g benzene per dm3.
The density of benzene= 0.8765 g/cm3.
1 dm3 benzene= 876.5 g.
in 1dm3 pure benzene there is 11.23 moles (876.5/78). Therefore the molarity of 100% benzene= 11.23 moles/dm3

pink_dust_angel
(Stranger)
06-08-04 19:16
No 512215

thnk u very much ppl now swim will be able to...

thnk u very much ppl now swim will be able to dream his dream
laugh