有關水結冰的物理問題

熱力學 份子運動理論-kinetic theory
一件物件internal energy(內能)= kinetic energy 動能( 平均數即溫度)+ potential energy 勢能
動能高就越熱，分子震得快d
勢能係當 particle 變態(固體 liquid gas互換)先會+/-
particle 之間有力(e.g.內聚力)連住，當動能ke夠就會突破到d力，分子就會分得越開pe勢能亦越高，所以會由固solid>liquid or liquid > gas，當動能ke不足分子就會比之間的力吸引，pe下降，物件由gas>liquid or liquid>solid。

noted that 當物件變態，ke unchanged (即係溫度唔會變)，pe increase/decrease
而所謂LATENT HEAT 潛熱 即係當變態個陣，因為自己溫度唔變，KE unchanged ，所以吸收嘅熱力納入PE/放出的熱力來自 PE。所以當水到左0度，要再有野吸走佢D PE 或者叫 latent heat 水先會變冰、變完冰都係0度，

0"C水同0"C冰 溫度一樣(KE SAME )不過冰PE低過水。(當冰同水都係同樣質量(份子數目))

而熱平衡是兩者溫度一樣所以就沒有熱的傳送，因為兩者KE一樣。
熱的傳送其中一個原因是因為份子間的碰撞把KE 就一PARTICAL 送到另一PARTICAL。

最後水結冰的條件: 要到左 freezing point先可能
noted that 係唔同外壓下 freezing point 都係唔同，係地球大氣壓力(normal atmospheric pressure )(100kpa)下，H2O 的冰點係0 度。
你可以理解為，把份子拉在一起的力有外壓和份子之間的力，當份子外面的壓力大，就要更大的力才能突破本身particle 之間的力和外壓，才可以提升PE之後變態。

如果唔知我up 咩可以問下學校phy 老師/form 3 讀phy

2012-12-06 15:30:01 補充：
唔明PE 勢能的話，最簡單係，有地心吸力拉住個波去地心，如果你放高D個波，PE就會高左
將同一想法放入partical 到就易明D

The temperature of the ice-water mixture (冰水混合物) is at 0'C.

When the bottle of water is cooled down to 0'C (the freezing point of water) by the ice-water mixture, thermal equilibrium (熱平衡) will be reached, as the wtaer in the bottle and the ice-water mixture are at the same temperature . There is no longer any flow of heat to and from the bottle water.

As turning water into ice needs the release of latent heat (潛熱), the absence of heat flow makes freezing of water in the bottle not possible.


2012-12-05 20:09:45 補充：
Your suppl question:
Water at 0'C cannot turn into ice by itself, unless heat is taken out from it. The amount of heat needs to be taken from the water to turn it into ice is called "latent heat"(潛熱).

2012-12-05 20:11:39 補充：
When the water in the bottle is cooled to 0'C. It is at the same temperature as the ice-water mixture. Because heat can only flow from high to low temperature, there is no heat flow from the bottle water into the ice-water mixture.

2012-12-05 20:12:56 補充：
As a result, no further heat can be taken from the water in the bottle. The temperature of water only remains at 0'C and cannot turn into ice.

水的比熱容量大,不易改變其溫度
2個溫度不同的物體接觸時,能量會由較熱的物體轉移至轉冷的物體，直到2個物體達到相同溫度，能量就停止轉移，這2個物體就達到熱平衡。
水要冷卻到凝固點(0度)時才會變成冰,水要凝固成冰要釋放出熔解潛熱(即額外的熱)。一個裝滿水的膠水瓶放在冰水混合物,膠水瓶內的水並沒有達到凝固點(0度)

在室溫時，液態水在溫度降低時密度會增加，這跟一般物質無異。但在接近冰點的4°C 時，水達到其最大密度。