What's a "pH balanced" shampoo?

Question

When I was growing up, just about every shampoo I came across advertised itself as being "pH balanced".  At the time I didn't know what "pH balancing" was and simply ignored it, trusting that all would become clear as I progressed through my education.

Now, however, I find myself an ostensibly fully educated adult and I still have no idea what a "pH balanced" shampoo is and how it differs from other, more prosaic, shampoos.

With the cynicism gained from a few decades of being bombarded by advertising, I think it likely that "pH balanced" is simply a set of impressive sounding words cobbled together by an advertiser in order to sell more shampoo (much like shampoos that promise "volume"?) but I still remain open to being educated otherwise.

So, what do you think?  Is "pH balancing" an actual phrase used by real chemists?  And if so, what does it mean?  Is is merely the act of creating a buffer or is there something more complex going on?

Thanks in advance!

Anonymous · Accepted Answer

I think shampoo poo

Chem Man · Answer

pH balanced means the shampoo contains a buffer, which keeps the pH of the shampoo the same, regardless of whether you wash your hair in slightly acidic or slightly basic water.

Two kinds of buffers are:
1. A weak acid and the salt of the weak acid. Example: H2CO3 and NaHCO3.
2. A weak base and the salt of the weak base. Example: NH3 and NH4Cl.

Take the case of a shampoo containing a buffer made from a weak acid and its salt.
HA -----> H+ + A- where HA is the weak acid and A- is its conjugate base.
Adding a base, OH-, to the buffer uses up some H+. The equilbrium shifts to the right to replace some of the H+ that was removed by the base (LeChatelier's principle). The amount of H+ is still about the same as before adding the base; the pH stays the same. (balanced pH)
Adding an acid, H+, to the buffer causes the equilibrium to shift to the left as the system tries to use up some of the added H+. The amount of H+ remains about the same as before adding the acid. (again, balanced pH)

Anonymous · Answer

pH balanced means that they are balanced to the natural acid and alcline levels of your hair and won't therefore corrode or damage your hair

Anonymous · Answer

jeesh a long time since chemistry but i think its to do with the level of acid and alkaline within the chemical build up, so a balanced ph level would be saying that it has a safe level of both acid and alkaline.

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What's a "pH balanced" shampoo?

4 Answers