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高中化学第二册钠跟乙醇反应测定乙醇结构的实验,较难得到准确的数据。我们对这个实验的装置、步骤作了改进,效果较好。在酸式滴定管中倒入无水乙醇,记下滴定管读数V_1,放出2毫升左右乙醇,到50毫升注射器内,(容量大的注射器可按比例增加);然后取1厘米长、直径为3毫米左右的一段较纯净的钠,放入注射器细管端口,注射器口朝上直立,(钠一般不会往不掉),推动针筒向上排出空气,保留细管端的空气柱,在端口加上橡皮塞,接着将注射器倒过来, 使乙醇与钠接触,至钠全部反应完毕;然后管口朝上,记下注射器读数(不包括剩余乙醇体积)V,即是氢气的体积。再把剩余的乙醇倒入滴定管,记下读数V_2,V_1-V_2就是消耗掉的乙醇的体积;最后根据数据计算。用这个方法进行实验,直观性、趣味性较强,产生的氢气推动活塞移动很明显,学生很感兴趣;
It is difficult to obtain accurate data for the experiment of determining the structure of ethanol by the reaction of sodium and ethanol in the second volume of high school chemistry. We have improved the device and steps of this experiment and achieved better results. Pour anhydrous ethanol in the acid burette, record the buret reading V_1, and discharge 2 ml of ethanol into the 50 ml syringe. (The syringe with a large capacity can be increased in proportion); then take 1 cm long and 3 mm in diameter. The left and right sections of purer sodium are placed into the syringe’s slim tube port, the syringe port is upright, (the sodium generally does not fall out), the syringe is pushed upward to discharge air, the air column at the end of the thin tube is retained, and the port is rubberized. Plug, then turn the syringe upside down and bring the ethanol and sodium into contact until the sodium has reacted completely; then the nozzle is up, note the syringe reading (not including the remaining ethanol volume) V, which is the volume of hydrogen. Then pour the remaining ethanol into the burette and record the reading V_2. The V_1-V_2 is the volume of the consumed ethanol. Finally, the data is calculated based on the data. Experiments with this method are more intuitive and interesting. Hydrogen generated by the pistons is obviously moving and the students are very interested;