测定分子间的氢键强度.doc

Ho Ngai College (Sp on sored by Sik Sik Yue n)Advanced-Level ChemistryExperiment 8The investigation of hydrogen bonding in a mixture of liquids 測定分子間的氫鍵強度Name : ( ) Experime nt Date : INTRODUCTION 弓 |言 在把液體混合的過程中，如液體分子間形成氫鍵、或有氫鍵被破壞，皆會產生焓變 本實驗是對這類焓變進行探究，並利用簡單的量熱法測量在乙醇分子間、或是在三氯 甲烷和乙酸乙酯分子間的氫鍵的大約強度CHEMICAL化學藥品etha nol 乙醇 cyclohexa nel 環己烷 ethyl etha no ate乙 酸乙酯 trichlorometha ne 三氯甲烷APPARATUS 儀器3 310.0 cm and 25.0 cm measuri ng cyli nders50 cm / 100 cm and 250 cm beakersThermometer (-10.0 -50.0 °C)LidBala neeCloth10 cm3和25 cm3量筒、50 cm3燒杯及杯蓋、滴管 2支、-10-110C溫度計、布CAUTION1. Etha nol, cyclohexa ne and ethyl etha no ate are flammable, trichlorometha ne is harmful.2. Mixtures of trichlorometha ne and propa none have bee n known to explode on sta nding. The solve nt residues from this experime nt should not be disposed of into a container in which propa none is prese nt.【危險警告：乙醇、環己烷和乙酸乙酯易燃。

危險警告：乙酸乙酯易燃、三氯甲烷有害PROCEDURE 步驟A.探測乙醇分子間氫鍵的存在1. 稱量並紀錄一個清潔而乾燥的 100 cm3燒杯的質量2. 用10 cm3量筒把10 cm3的乙醇加進以上 100 cm3燒杯中3. 在燒杯外包上布條（或毛巾），使用溫度計穿過杯蓋中心4. 使用溫度計去量度液體的最初溫度並紀錄在下表5. 使用50 cm3的量筒將10 cm3的環己烷加入燒杯中的乙醇內 ，並充份混和6. 量度並記錄液體所得的最後溫度B.量度乙醇分子間氫鍵的強度重複甲部的步驟 ⑴ 至（6）,但改用20 cm3的環己烷進行實驗c.探究乙酸乙酯和三氯甲烷分子間的氫鍵的形成【危險警告氯甲烷和丙酮的混合物在存放時可能會發生爆炸，因此切勿將本實驗剩餘的溶劑棄置在盛有丙酮的容器內1. 用10 cm3量筒把10 cm3的乙酸乙酯加進清潔的 100 cm3燒杯中2. 在燒杯外包上布條（或毛巾），使用溫度計穿過杯蓋中心3. 使用溫度計去量度液體的最初溫度並紀錄在下表4. 使用50 cm3的量筒將10 cm3的三氯甲烷加入燒杯中的乙醇內 ,並充份混和5. 量度並記錄液體所得的最後溫度D.量度乙酸乙酯和三氯甲烷分子間氫鍵的強度重複甲部的步驟（1）至（5），但改用10 cm3的其中一種液體和的 20 cm3另一種液體互相混和。

哪種液體選用10 cm3而哪種選用20 cm3並不重要REMARK1. The bulb of the thermometer should be completely immersed in the mixture.2. The temperature reading should be accurate to1 decimal place3. 2-3 students work in a group.GIVENRAM. (g mol ) : H = 1.0 ; C = 12.0 ; O = 16.0 ; Cl = 35.5 Specific heat capacity of glass = 0.78 kJ kcj K-1液體化學式相對 分子質量密度/ kg dm-3比熱容/kJ kg" K-1乙醇CH3CH2OH460.812.44環己烷C6H12840.781.83三氯甲烷CHCI3119.51.480.98乙酸乙酯CH3CO2CH2CH3880.901.92RESULTBCDWeight of the in sulated beakers / g Finalotemperature / C In itial temperature / C Temperature change / C數據提供以下的物理數據可作為考之用:玻璃的比熱容 =0.78 kJ kgT K _1液體化學式相對 分子質量密度/ kg dm~3比熱容/kJ kgT O1乙醇CH3CH2OH460.812.44環己烷C6H12840.781.83三氯甲烷CHCI3119.51.480.98乙酸乙酯CH3CO2CH2CH3880.901.92QUESTIONS1. Explain why the beaker should be wrapped by a cloth and covered by a lid in this experiment.為什麼在這實驗裏 , 燒杯外圍須包著布料及蓋上杯蓋 ?2. Based on the experimental result, state whether the mixing of ethanol and cyclohexane is endothermic or exothermic.根據實驗結果 , 指這乙酸和環己烷的混和是放熱反應或是吸熱反應 ?3. Account for the change in temperature on mixing ethanol and cyclohexane. 解釋乙醇和環己烷混合時的溫度變化的成因。

4. Determine whether ethanol or cyclohexane is in excess in part B. Explain why you think it must be in excess.解釋為何這實驗須用過量的環己烷5. Determine the strength of the hydrogen bond in ethanol according to the results obtained in part B.從溫度下降的幅度估計乙醇中氫鍵的強度 （以kJ mol"表示）6. Based on the experime ntal result, state whether the mixing of ethyl etha no ate and trichlorometha ne is en dothermic or exothermic.根據實驗結果，指這乙酸乙酯和三氯甲烷的混和是放熱反應或是吸熱反應 ？7. Acco unt for the cha nge in temperature on mixing ethyl etha no ate and trichlorometha ne. 解釋乙酸乙酯和三氯甲烷混合時的溫度變化的成因。

8. Determine the strength of the hydrogen bond formed between molecules of ethyl etha no ate and trichlorometha ne accordi ng to the results obta ined in part D.從溫度下降的幅度計算乙酸乙酯和三氯甲烷間氫鍵的強度 （以kJ moF1表示）。