what is the meaning of 明礬(Alum

What is the meaning of 明礬(Alum)?
(1)鉀鋁礬又稱鉀礬、因顏色为透明（帶白色）故稱明礬，化學式為KAl(SO4)2‧12H2O。
明礬只是一個通稱，因為在一般的明礬石中，可能會有其他成份存在。例如鈉鋁礬Sodium alum, Na2SO4Al2(SO4)324H2O和銨鋁礬Ammonia alum, NH4Al(SO4)212H2O。
用途為淨水劑，媒染劑 ，造紙 ，製筆 ，，製皮革 ，製油條 等。
(2) Alum refers to a specific chemical compound and a class of chemical compounds. The specific compound is the hydrated aluminum potassium sulfate with the formula KAl(SO4)2.12H2O.
The wider class of compounds known as alums have the related stoichiometry, AB(SO4)2.12H2O. eg Sodium alum, Na2SO4Al2(SO4)324H2O and Ammonia alum, NH4Al(SO4)212H2O.
Their uses are astringent/styptic and antiseptic. deodorant , medicine. it is called ming fan(明礬) in Traditional Chinese Medicine.

礬係化學物質，係雙硫化物結晶。一般係跟以下結構M+2SO4·M3+2(SO4)3·24H2O 。M+代表鹼金屬，好似鋰，鈉，鉀，銣，銫咁。而M3+就係三價金屬，好似鋁，鉻同鐵咁。而銨離子(NH4+)都可以響呢個位出現。

呢隻鹽係用來染料或者其他工業製作。佢溶響水，味又澀又酸又甜。用石蕊來試係酸性。結晶係正八面體。加熱會熔，再熱啲，裏面嘅水份子就走面出來，舊鹽會起泡同脹晒，最後變成一堆粉，唔再係晶體。

明礬係最常見嘅礬。

Alum, refers to a specific chemical compound and a class of chemical compounds. The specific compound is the hydrated aluminum potassium sulfate with the formula KAl(SO4)2.12H2O. The wider class of compounds known as alums have the related stoichiometry, AB(SO4)2.12H2O.