Miscibility: Hexane, Ethanol, and Water

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Page ID: 131412

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Required Training	Required PPE
UC Lab Safety Fundamentals	Lab coat, safety glasses/goggles, nitrile gloves

Equipment	Chemicals
DI Water Bottle	400 mL Hexane
1 L Screw Top bottle	400 mL Absolute Ethanol
	4-10 Crystals Iodine (to color)

Procedure:

Measure 400 mL pure ethanol into the screw top bottle.
Measure 400 mL hexane and add it to the screw top bottle as well.
Stir in a few crystals of iodine to provide a color deep enough to contrast clear water.
Squirt a few mLs of water into the mixture and invert. Two layers should separate.
Continued shaking will encourage further mixing of the two layers.

Discussion:

This demo seems to challenge the rule of thumb “like dissolves like.” Ethanol has a short alkane tail and a hydrophilic –OH head. One can imagine a situation in which the –OH groups exchange hydrogen bonding, allowing for hexane to interact with the –CH₃ tails. However, when water is added…??? The density of water is 1.0 g/mL while the density of hexane is 0.65 g/mL and the density of ethanol is 0.79g/mL.

Hazards:

Hexane and ethanol are known to have serious health effects (reproductive hazards, carcinogenic effects, flammability, and acute toxicity.) Be sure to read the SOPs provided on what to do in the case of a spill. In general, spills of flammables like hexane and ethanol should only be handled independently if safe. Call EH&S or the fire department if you think a spill is out of your control.

SOP

Carcinogen – Hexane

Potential Reproductive Hazard – Hexane

Disposal (by Storeroom)

Proper disposal will be dealt with by the dispensary. The used demo solution will be submitted as waste to EH&S.