高中學生應用勒沙特列原理判斷非均勻相系化學平衡的迷思概念探討

An Investigation on Senior High School Students' Misconceptions of Applying Le Chatelier's Principle under Heterogeneous Systems on Chemical Equilibrium

李世峰(Shih-Feng Lee) ； 李田英(Tein-Ying Lee)

《科學教育月刊》 301期 (2007/08) Pp. 2-16

https://doi.org/10.6216/SEM.200708_(301).0001

摘要

本研究探討高中學生應用勒沙特列原理判斷非均勻相系化學平衡的迷思概念。參與研究之學生爲桃園市某校高三學生332名，研究工具爲研究者分析學生在開放式試題結果所得資料，設計一份涵蓋七個中心概念，總數50題的二段式測驗。試題的第一部份是檢驗學生對知識了解的正確性，第二部份則是探究學生之所以持此種認知的理由。試題內容效度經由四位具化學專業的高中化學教師審核評定，測驗的庫李信度爲0.81。測驗資料分別以描述性統計及皮爾遜(pearson)積差相關分析，結果發現41項有關勒沙特列原理之迷思概念，其中有19 項乃國內外研究類似之發現，另22項爲本研究所特有。最顯著的迷思概念有：1.不論反應物種的濃度改變與否，59%的學生認爲平衡前正反應速率等於平衡後正反應速率，同理平衡前逆反應速率亦等於平衡後逆反應速率；2.在鹽類溶解度平衡中，41.6%學生認爲難溶性鹽類易解離或是以爲鹽類皆可溶，使濃度改變造成平衡移動；3.定容、定壓下，30.9%的學生認爲加入惰性氣體不影響平衡；4.有31.6%的學生認爲體積加倍，活動空間變大，碰撞機會變小，正、逆反應速率改變。建議能在教學前先了解學習主題主要的迷思概念類型，區分特質編寫化學教材提供學生正確知識，搭配反應速率對時間作圖的方式教學，讓學生從圖形概念中體會速率與時間在濃度、壓力、溫度等因素變化下的相對關係，可幫助學生對化學平衡建立正確概念減少迷失。

關鍵字

勒沙特列原理 ； 非均勻相系 ； 二段式測驗 ； 迷思概念

並列摘要

The study as aimed at investigating the misconceptions of applying Le chatelier's principle under heterogeneous chemical equilibrium systems for senior high school students in Taiwan Three hundred and thirty-two 12th grade students in Taoyuan who had studied chemical equilibrium participated in the study A two-tier test as developed based on the analysis of students' answers on an open-ended test There are 50 multiple-choice items, including seven central concepts, where the content knowledge as examined in the first tier and students' understanding of that know ledge in the second The test as validated by four senior high school teachers ho possessed profound professional chemistry knowledge, The reliability (KR-20) is 0.81 Data were analyzed through descriptive statistics and pearson product-moment correlation The results indicated a list of 41 patterns of misconceptions underlying misuse of Le chatelier's principle, 19 of which are identified in literature, whereas 22 of them are unique to this research The most significant key-miconceptions revealed by the study are:
1. Whatever concentration of reactant may change, the rate of the forward (or reverse) reaction on initial chemical equilibrium should be equal to the rate of the forward (or reverse) reaction on final chemical equilibrium.
2 When insolube salt is dissolved in pure water to form a saturated solution, an equilibrium is established between the solid and its ions in solution The student thought all the insoluble salt could be dissolved, which could change the solubility equilibria.
3 The student contended the temperature and pressure on constant, the chemical equilibrium wouldn't be influenced by adding noble gas.
4 The student contended as the volumn increases, the probability of collision ill decrease, which may result in the decrease of the rate of chemical reaction.
Propose understanding the main misconception patterns of the learning topic, distinguishing the speciality and writing chemistry teaching materials to provide students correct know ledge before instructing Collocate with instructions through diagramming on reaction rates and time to help students realize relative relationships between rates and time under such factors as concentration, pressure and temperature so as to help students set up correct concepts on chemistry equilibrium as v dl as avoid losing.

並列關鍵字

Le chaterlier's principle ； heterogeneous systems ； two-tier test ； misconception