請問測試是否純金既方法係咩野??

物理方法：可以用小學那種排水法量度一物質的質量...再與真正的純金比較..
差不多的話..即是純金 =]


化學方法：放在酸裡..
正常情況下..金不會同酸產生任何化學反應（因為金是不活躍的）
如果有其他雜質or金屬..就會同酸產生反應...出現泡沫
純金的話...就不會出現泡沫 =]

可以用質譜儀(mass spectrometer)
用返週期表個mass
再用質譜儀測個mass對下

x光反射(x-ray defection)
睇下個atom既排列

原子發射光譜(atomic emission spectra)
因為每一隻原子吸收的光譜不一
所以有不同的不連續光線(discrete line)
咁對返金既發射光譜就知

it is really hard to do so as gold is very unreactive
it exists as free element in nature

but i can tell you about how to find the percentage by mass of silver in
a silver coin with known mass
first of all, treat the coin completely with concentrated nitric acid
silver nitrate is one of the product
afterwards, treat the resulting solution with excess potassium chloride solution
silver nitrate will react with potassium chloride to form insoluble white silver chloride
filter the silver chloride out and clean it with distilled water and dry
weigh the silver chloride
let the mass of silver chloride be y gram
no. of mole of AgCl = y / molar mass of AgCl = no. of mole of Ag in coin
mass of Ag in coin = y / molar mass of AgCl * molar mass of Ag
percentage by mass of Ag in coin = mass of Ag in coin / mass of coin * 100%