熱學- 計混合物未溫度 { 中文 }

ching_lene

2007-05-12 5:37 am

QUESTION-
把0.5KG溫度為0度的永和1KG溫度為20度的水混和,
假設混合物和周圍環境之間沒有熱傳遞,
找出混合物的溫度

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最好有詳細的問答過程=[]=

更新1:

第2題- 在隔熱的器皿內利用浸沒式電熱器把一種液體以10J s^-1 的速度加熱, 把液體煮沸後再繼續加熱3分鐘後, 液體的質量少了10g, 從這實驗結果, 永液體的汽化比潛熱. PS- 我係想學識點計.. 唔係剩係想要答案

回答 (1)

天同

2007-05-14 3:24 am

✔ 最佳答案

1. Heat given out by water when its temperature falls to 0 deg.C
= 1 x 4200 x 20 J = 84000 J
Heat absorbed by ice if it melts completely = 0.5x 334000 J = 167000 J
where 334000 J/kg is the latent heat of fusion of water
Since the heat given out by the water is not sufficient to melt all the ice, the final temperature is still at 0 deg.C with water and ice in equilibrium.
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2. Energy given out by the heater in 3 minutes = 10 x 3 x 60 J = 1800 J
The heat is absorbed by 10/1000 kg of liquid to become vapour.
thus latent heat of vapourization = Heat absorbed/mass of lquid
= 1800/0.01 J/kg = 180 000 J/kg

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