to determine the enthanply change for a reaction(20分,急~)

2007-11-12 5:14 am

to determine the enthanply change for this reaction
mgso4+7h2o=mgso4.7h2o
點解呢個reaction 既enthanply change 唔可以直接measure?要咁樣去計?
mgso4+100 h2o=mgso4(aq,100h2o)
mgso4.7h2o+93 h2o=mgso4(aq,100h2o)
(將呢兩個 reaction 既 enthanply change 相減)

另外,進行呢個實驗有咩要注意?

回答 (1)

永威

2007-11-12 10:27 am

✔ 最佳答案

li個reaction ...點解measure唔到因為冇方法係可以直接measure
因為當mgso4 放係空氣入面佢就會慢慢變mgso4.7h2o
由於佢既速度太慢當佢既enthalpy 改變完因reaction 而改變energy可能已經即gain返/lose 返d from surroinding
reaction 而改變energy

所以係"experimentally" 係measure唔到

做li個實驗當然要留意既係佢既energy loss/gain due to surrouding
所以有小心去做保溫

1. 用polystyrene cup 仲要用cover 因為咁樣會減小 effect from surrounding

2. 記得measure個溫度要stir左咁樣先令solution既temp 平均 measure會準d

3. 記得stir "唔好太快" 因為太快會產生熱咁就唔準嫁啦

參考: 我(對唔住習慣左用英文所以中英夾雜唔好見怪)

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