二硫基丙磺酸钠

• 二(number two; two horizontal strokes)ASSOCIATIVE

Two parallel horizontal strokes symbolize the number two.

• 一(one; horizontal stroke on top)RADICAL
• 内(inside; within)ASSOCIATIVE

The third stem Bing carries fire blazing from inside outward.

• 酉(wine vessel; ferment)RADICAL
• 夋(slow manner; leisurely pace)PHONETIC

Fermenting alcohol produces sourness, which is exactly the character for sour.