Sng-hòa (Eng: oxidation) sī chi̍t khoán hòa-ha̍k hoán-èng, kòe-têng tiong sit khì tiān-chú ā-sī kóng chin-ka sng-hòa chōng-hóng, it-poaⁿ sī sng-sò͘ teh chham-ka chok-iōng, chō-sêng chhin-chhiūⁿ seⁿ-sian, jiân-sio, sin-thé tài-siā pàng chhut la̍t-thâu téng-téng hiān-siōng.