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### Topic: molecular formulas  (Read 6055 times)

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#### 8

• Guest
##### molecular formulas
« on: January 14, 2005, 11:30:13 AM »
What are the molecular formulas of standard cooking oils? ie (crisco, olive, sunflower, canola etc..) i'm doing an experiment to find the molar enthalpy of some oils, but i cant seem to find the molecular formulas anywhere..? please help

#### Demotivator

• Guest
##### Re:molecular formulas
« Reply #1 on: January 14, 2005, 12:08:30 PM »

#### 8

• Guest
##### Re:molecular formulas
« Reply #2 on: January 14, 2005, 03:53:56 PM »
so would it be adequate to use Oleic acid in the calculations since it is the primary (55-85%) source in the composition of olive oil? How would i account for the other parts?
« Last Edit: January 14, 2005, 03:55:14 PM by 8 »

#### Demotivator

• Guest
##### Re:molecular formulas
« Reply #3 on: January 14, 2005, 04:14:26 PM »
Just oleic would be a fair approximation.
It would be a somewhat better approximation to calculate a weighted average molecular weight based on a typical composition.

#### 8

• Guest
##### Re:molecular formulas
« Reply #4 on: January 15, 2005, 05:35:54 PM »
hmm..ok..so would this be the way to do it?

Composition of Canola Oil:
Oleic acid: 62% and Linoleic Acid 22% and Stearic Acid 2% and Palmitic Acid 4%

[(0.62)(mass of C17H35COOH) + (0.22)(mass of C17H29COOH) + (0.02)(CH3(CH2)16COOH) + (0.04)(C15H31COOH)]

so my approximated mass of canola oil  is 253.6304g/mol

Can anyone verify these calculations? thx
« Last Edit: January 15, 2005, 08:00:57 PM by 8 »

#### Demotivator

• Guest
##### Re:molecular formulas
« Reply #5 on: January 15, 2005, 08:54:14 PM »
Yes, that is the way.

An alternative approach is just to base the experiment on enthalpy per gram oil instead of per mole oil. In that case there is no need to know composition or molecular weight, just grams used. Unless you prefer not to do it that way.