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初中物理第二册74页有萘的熔解图象,(见图1)横坐标表示加热时间,纵坐标表示温度。AB部分表示萘吸收热量,温度升高,(55℃～80℃)加热时间5分钟。BC部分是萘吸收热量,处于熔解过程,加热时间4分钟。一般认为;当物质质量不变时,可视作物质吸收热量与加热时间成正比。那么从图象中可知:假设萘熔解前(AB部分)吸收热量为Q_1,熔解时(BC部分)吸收热量为Q_2,则: Q_1:Q_2=5:4 (1) 查表又知:萘的比热c=0.29卡/(克·℃).其熔解热λ=36卡/克,另据 Q_1=cm△t,Q_2=λm,那么Q_1:Q_2=1:5 (2) 比较(1)(2)两式说明萘的熔
The junior high school physics second volume 74 pages have a fusion image of naphthalene, (see Figure 1). The abscissa indicates the heating time and the ordinate indicates the temperature. Part AB indicates that the naphthalene absorbs heat, the temperature increases, and the heating time (55° C.-80° C.) is 5 minutes. In BC, naphthalene absorbs heat and is in the melting process. The heating time is 4 minutes. It is generally believed that when the mass of material is constant, it can be considered that the heat absorbed by the material is proportional to the heating time. Then we can see from the image: Assume that the absorption heat of the naphthalene before melting (AB part) is Q_1, the heat absorption when the melting (BC part) is Q_2, then: Q_1:Q_2=5:4 (1) Look up the table and know: Naphthalene Specific heat c=0.29 card/(g·°C). The heat of fusion λ=36 cal/g, and according to Q_1=cmΔt, Q_2=λm, then Q_1:Q_2=1:5 (2) Comparison (1) (2) Two formulas indicate the melting of naphthalene