我想問有甚麼方法從海水中提取純正鹽

以我所知..NaCl係係海水中既一種物質
係實驗室可以用過濾既方法將不溶於水的物質從海水中分離出黎既
再用蒸發法可以得到NaCl喇

If you want to get sea salt, this method is OK,but you CANNOT obtain pure NaCl by this way!!

In fact, both evaporation and crystallization cannot form pure salt.
Salt form by crystallization is just more pure( NOT pure!! ) than that by evaporation.
Only neutralisation with exactly the same amount (EXACTLY) of acid and alkali can form pure salt.

用蒸餾法 distillation

First, heat the sea water until the solution is saturated.
Then. keep it for a few days for the water to evaporate slowly (don't cover it!!).
You will then find some pieces of crystals(NaCl) which is quite pure.