[Mohammed Shuaib]

Mohammed Shuaib  asked the Naked Scientists:
   
Can you use shampoo to start a fire???





What do you think?

[Bored chemist]

Most shampoos I have seen are mainly water.
Not ordinarily a good way to start a fire but it's possible.

A spherical bottle filled with shampoo would act as a lens and you could use that to focus the sun's heat to start a fire.

[CliffordK]

Soap is primarily long chain hydrocarbons.  So, it should burn reasonably well.  However, as Bored Chemist says, if it also contains water, then that would tend to make it much less flammable. 

You might try powdered laundry detergent.

Or, attempt to dehydrate your soap or shampoo before trying to light it.

[Bored chemist]

Most shampoos I have seen don't contain soap.

[RD]

An exothermic reaction occurs when making soap ...

Saponification is the chemical process of making soap that involves an exothermic reaction between lye (sodium hydroxide) and a fat (usually oils).

http://www.certified-lye.com/lye-soap.html

Sodium hydroxide ... can react violently with water and numerous commonly encountered materials, generating enough heat to ignite nearby combustible materials. Contact with many organic and inorganic chemicals may cause fire or explosion.

http://www.ccohs.ca/oshanswers/chemicals/chem_profiles/sodium_hydroxide/basic_sod.html

[CliffordK]

You might try aerosol hair spray as a fire starting aid.

[Sprool]

Most shampoos I have seen don't contain soap.

What is your definition of soap? Every commercial shampoo contains SLS or SLES (sodium lautheth sulphonate and related detergent molecules). These are detergent molecules, dissolved in water, forming a lather or foam and used to aid degreasing/cleaning process. That to me falls under the definition of soap.
Long chain carbons they may be but at only 5% in water they are not going to burn, just like 5% ethanol in water will not burn, eg: beer.

[Bored chemist]

"What is your definition of soap?"
Already answered.
Saponification is the chemical process of making soap that involves an exothermic reaction between lye (sodium hydroxide) and a fat (usually oils)

[Sprool]

Sorry, no cigar, you have answered a different question. The definition of making soap. I prefer my answer to what soap is. Any way, not wishing to be pedantic, you still can't use shampoo to light fires.

[Bored chemist]

"I prefer my answer to what soap is"
You are entitled to your opinion, but it's not widely accepted. Your definition of soap is actually the definition of detergent (roughly)

Soap is the product of hydrolysis of fat by sodium hydroxide

[Sprool]

"Soaps and detergents are not the same thing, although both are surfactants, or surface active agents, which basically means a washing compound that mixes with grease and water, forming a foam or lather.
Soaps are made of materials found in nature. Detergents are synthetic."

Shampoos contain SLS and SLES which are synthetic thus detergents, though for most people the FUNCTIONAL distinction between soap and detergent is irrelevant.
You still cannot use shampoo to start a fire!

[Bored chemist]

R. "You still cannot use shampoo to start a fire!"
Nobody said you could.
However, I strongly suspect that you could, in fact, start a fire with shampoo.
http://www.instructables.com/id/How-to-Start-Fire-with-Water/

Incidentally, if you live in a hard water area, the FUNCTIONAL difference is soap scum in your hair.

[Sprool]

Nobody said you could

The O/P asked if you could.
http://www.instructables.com/id/How-to-Start-Fire-with-Water/
You mean - how to start fire with ammonium nitrate, salt and zinc powder and a drop of water?
(not shampoo...)
You might as well say  you can blow up a bridge with a bag of TNT that may have a shampoo bottle on one of the pockets. The presence of shampoo is largely irrelevant, it would just happen to have some water in it. Thus in the above link it's the action of the water not the surfactant that kicks off the reaction.

[Bored chemist]

True but shampoo is, as you pointed out, more water than surfactant so it would probably start the fire.

[Sprool]

You have a point

[redreed]

Hmm,stupid me is wondering why would anyone light a fire with shampoo?

[damocles]

Out of matches and shops closed  []

[cheryl j]

My organic chemistry professor said soaps and detergents are definitely not the same thing and behave differently in many ways, one example being soap's tendency to combine with minerals and leave a ring in your bath tub. Another bath tub experiment you can do is fill your tub with bubble bath ( a mild detergent) and then lather up with a cake of soap and watch what happens to your lovely bubbles.