Boric acid imparts a pale green color to a flame.

Boric acid is one of the few min-er-al acids which is ca-pa-ble of form-ing com-plex es-ters. Es-ters of boric acid burn with a green flame, and this prop-er-ty is used in an-a-lyt-i-cal chem-istry for de-tect-ing boric acid and its salts. Pure es-ters of boric acid burn at a tem-per-a-ture of around 30 °С, so you can safe-ly put your hand in the flame.

A very pale green color is imparted to the flame by boron in boric acid. Because, Boric Acid is a boron containing compound Any boron-containing compound will cause flames to emit a green colour. When boron compounds are heated, electrons absorb a certain amount of heat energy that causes them to jump to higher energy levels.