潛熱的問題??有關變態

Q:如果我把水放入0℃ 會變冰...變左冰又會變水 之後會係咁重複?

No, this would not happen.In order for ice/water to change state, there must be heat flowing into or out of the subtance. But heat only flows when there is a temperature difference.

Hence, if you put 0'C ice into 0'C water, The ice would not melt and the water would not freeze into ice, because there is no temperature difference between ice and water (as both of them are at 0'C). As such, no heat would flow from the water to melt the ice. The ice and water co-exist in equilibrium.

However, if you put 0'C ice into 1'C water, say, then the ice would melt. It is because there is now a temperature difference between water (at 1'C) and ice (at 0'C), this temperature difference casues heat to flow from the water to ice, until both of them are at the same temperature (i.e. in state of thermal equilibrium).


2010-10-08 13:51:23 補充：
Q:水係0℃時都係水,冰係0℃時都係冰,係咪咁?
Yes, it is true, as there is no heat flow because of no temperature difference.

潛熱係咪解係溫度不變的(請)況下 把物態改變 係過程中得到/放出的能量就係潛熱??但係溫度不變點可以把水變冰?

correct.
since it can absorb or release energy(potential energy)without any change of temperature(kinetic energy)

水係0℃會放出能量 之後會變冰
冰係0℃會得到能量 之後會變冰
WRONG!
IT IS
咁水係0℃會<釋放>能量 之後會變冰
咁冰係0℃會<ABSORB>能量 之後會變冰