●●● ●●●● 2. Experimental principles ●●●●● ●●●● ●●●●● ●●●● Electrophoresis of colloids Under an external electric field the colloidal particles moving to the positive electrode or negative electrode, this phenomena is called electrophoresis o Electrophoretic potential can be measured by electrophoresis through two methods: microscopic method and macroscopic method
⚫ Electrophoresis of colloids ⚫ Under an external electric field the colloidal particles moving to the positive electrode or negative electrode, this phenomena is called electrophoresis. ⚫ Electrophoretic potential can be measured by electrophoresis through two methods: microscopic method and macroscopic method. 2. Experimental principles
●●● ●●●● ●●●●● 3.Apparatus and reagents ●●●● ●●●●● ●●●● Apparatus Electrophoresis apparatus; Electrophoresis tube; Stopwatch; Pt electrode, 2; 100mL Beaker, 3; Plastic head dropper, 2 25mL Graduated flask, 2. and so on Reagents Silver nitrate solution(0.01molL); Potassium iodide solution(0.01mol/L); Potassium chloride solution(0.005mol/L)
3.Apparatus and reagents ⚫ Apparatus ⚫ Electrophoresis apparatus; Electrophoresis tube; Stopwatch; Pt electrode, 2; 100mL Beaker, 3; Plastic head dropper ,2;25mL Graduated flask, 2 , and so on. ⚫ Reagents ⚫ Silver nitrate solution (0.01mol/L); Potassium iodide solution (0.01mol/L); Potassium chloride solution (0.005mol/L)
●●● ●●●● ●●●●● 4.Experiment procedures ●●●● ●●●●● ●●●● o Preparation of AgI negative solution 20mL 0.01mol/L KI(Potassium iodide) solution is added to a 1ooml beaker. 18.7ml 0. 01moVL AgNO3(Silver nitrate)solution is dropwise added to the beaker under stirring agl negative colloid s prepare
⚫ Preparation of AgI negative solution ⚫ 20mL 0.01mol/L KI (Potassium iodide) solution is added to a 100mL beaker, 18.7mL 0.01mol/L AgNO3 (Silver nitrate ) solution is dropwise added to the beaker under stirring, AgI negative colloid is prepared. 4.Experiment procedures
●●● ●●●● ●●●●● 4.Experiment procedures ●●●● ●●●●● ●●●● ● Determination of potential .(1)The electrophoresis apparatus should be washed clean .(2) Fixed the electrophoresis apparatus vertically on the iron support stand 3 Close the piston, Add colloid through the funnel with plastic head dropper .(4 Assistant solution is added into the U-tube . (5)Open the piston slowly, when colloid up to 0-tick, close the piston (6 Gently insert two electrodes, immerge assistant solution lcm (pUsh the electrophoresis apparatus's "start"button, and ith record the time that the interface rising 0.5, 1.0, 1.5 cm cost wit a stopwatch 8Turn off the power, measured the distance of two electrodes by a ruler. Wash the apparatus
⚫ Determination of potential ⚫ (1) The electrophoresis apparatus should be washed clean ⚫ (2) Fixed the electrophoresis apparatus vertically on the iron support stand ⚫ (3)Close the piston, Add colloid through the funnel with plastic head dropper ⚫ (4) Assistant solution is added into the U-tube ⚫ (5) Open the piston slowly, when colloid up to 0-tick，close the piston ⚫ (6)Gently insert two electrodes, immerge assistant solution 1cm ⚫ (7)Push the electrophoresis apparatus’s “start” button, and record the time that the interface rising 0.5, 1.0, 1.5 cm cost with a stopwatch. ⚫ (8)Turn off the power, measured the distance of two electrodes by a ruler. Wash the apparatus 4.Experiment procedures
●●● ●●●● ●●●●● 5. Experiment results processing ●●●● ●●●●● ●●●● .(1 Summarize the method of preparation of colloid .(2)Calculate 5 potential of AgI negative colloid
⚫ （1）Summarize the method of preparation of colloid; ⚫ （2）Calculate ξ potential of AgI negative colloid. 5.Experiment results processing