1.Experiment preparation
Laboratory equipment,pharmaceuticals,materials:cotton thread,silk thread,two 200ml beakers,a piece of cardboard,a number of filter papers,a kerosene lamp,asbestos net,iron stand with hoops,thermometer,copper sulfate powder,and a glass rod.
2.Experimental procedure
(1) Pour 100 ml of distilled water into abeaker and heat it to a temperature 10 to 20 ° C higher than room temperature,and add sufficient quantities of copper sulfate;
(2) Stir with a glass rod,until saturated(a small amount of crystal cannot be dissolved),filter the hot solution to a heated beaker;
(3 )Cover the beaker with a cardboard,and allowed to stand overnight to let it slowly cooling down and crystalized.
(4) The next day small crystals appear at the bottom of the beaker,each about 12.5px long,then take a relatively complete crystal,fasten to a wooden stick with a silk thread.
(5) Heat the solution to a temperature 5 to 10 ° C above room temperature,add a small amount of copper sulfate,and make it saturated again.
(6) Put the fastened copper sulfate crystal into warm saturated copper sulfate solution,note that it is completely submerged,and does not touch the wall or bottom of the beaker.
(7) Cover the beaker with a cardboard,and allowed to stand overnight; observed daily,and repeat the procedure of steps 6 and 7.
3.Experimental care
(1) Control the temperature of the solution,the crystal should be removed before heating the solution,the crystal is immersedin solution when temperature became uniform.
(2) Pay attention to the change of ambient temperature,the saturated solution should be cooled slowly.
(3) Containers used must be clean,and must be covered to prevent falling in dust.
4.Experimental conclusions
(1) The solubility of copper sulfate increases with the rising of temperature,crystal forming rate speeds up by strict control of temperature changes;
(2) The model must be suspended in the solution.If the model and the glass laminating,after cooling the solution,precipitated crystal will adhere between the coil and the glass,and the forming of the crystal shape will be irregular.