....... Some studies have linked mouthwashes with high alcohol content to cancer ... "
(http://www.smh.com.au/lifestyle/beauty/listerine-cancer-claim-triggers-court-battle-20110829-1jh63.html)
At concentrations above 60% by volume, ethanol is an antiseptic that kills bacteria, fungi and some viruses by denaturing their proteins and dissolving their lipids. The ethanol content of a mouthwash can be around 20% by volume, which is substantially greater than the alcohol content of most wines at around 12% v/v, but less than that required to act as an antiseptic.
| One of the antiseptic agents present in mouthwash is thymol, shown to the right.
The concentration of thymol in mouthwash can be about 0.0063% w/v. Thymol is only slightly soluble in water, but it is very soluble in ethanol. |  |
Typically, a person will use 20mL of mouthwash twice a day to rinse the mouth, and will spit out the mouthwash rather than swallowing it.
Further reading:
Lipids
Proteins
Functional Groups
Molecular Mass Calculations
Weight/Volume Concentration
Study Questions:
- Give the molecular and structural formula for ethanol.
- Explain what Chemists mean when they refer to the denaturing of a protein.
- What is a lipid?
- What are the elements that are present in all proteins?
- What are the elements that are present in all lipids?
- Give the molecular formula for thymol.
- On the structural formula of thymol, circle the functional groups present.
- What is the molecular mass (formula weight) of thymol?
- What mass of thymol would be present in 20mL of mouthwash?
- How much ethanol would be present in a 750mL bottle of mouthwash?
- How much ethanol would be present in a 750mL bottle of wine?
- In Australia, a standard drink is defined as one that contains 10g of pure ethanol. How many standard drinks are present in:
- 750mL bottle of wine?
- 750mL bottle of mouthwash?
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