acid, bitterness, sour, tart
酸 centers on a sharp, biting taste: sourness, tartness, or the chemical sense of acid. Bitterness is a related harsh flavor, though not identical.
酸 combines 酉 (a wine jar, suggesting fermentation) with 夋, which likely contributes the sound. The idea is the sour taste of fermented liquid.
The left side 酉 is a wine jar, and the right side 夋 looks like a person puckering from a sour taste. Imagine tasting fermented wine and making a sour face.
For サン, picture the sun (サン) beating down on a wine jar, turning the wine sour and acidic.
acid
oxygen (O)
oxidation; oxidization
carbonic acid
carbon dioxide; CO2
amino acid
lactic-acid bacilli
sourness; acidity
fatty acid
sulfuric acid; sulphuric acid
acidity
sour; acid
acetic acid
sweet and sour
hydrochloric acid
hydration
lactic acid
glutamic acid
nucleic acid
monoxide