PH PH In chemistry, pH () is a logarithmic scale used to specify the acidity or basicity of an aqueous solution. It is approximately the negative of the base 10 logarithm of the molar concentration, measured in units of moles per liter, of hydrogen ions. More precisely it is the negative of the base 10 logarithm of the activity of the hydrogen ion. At 25 °C, solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are basic. The neutral value of the pH depends on the temperature, being lower than 7 if the
Thioglycolic acid also used in so-called "fallout remover" or "wheel cleaner" to remove iron oxide residue from rims. Ferrous iron combines with thioglycolate to form red-violet ferric thioglycolate. Thioglycolic acid is prepared by reaction of sodium or potassium chloracetate with alkali metal hydrosulfide in aqueous medium. It can be also prepared via the Bunte salt obtained by reaction of sodium thiosulfate with chloroacetic acid: Thioglycolic acid is about 100 times stronger acid than acetic acid with a pKa of 3.83: The second ionization has a pKa of 9.3: Thioglycolic acid is a reducing agent, especially at higher pH. It oxidizes to the