Electric Conductivity of Salt Crystals, Melts and Solutions

10 Electric Conductivity of Salt Crystals, Melts and Solutions 

Problem Salts are substances, which are composed of ions - because of their charge the ions are capable of moving in an electrical field. But the ions are statically built into solid crystal and cannot move no conductivity can be ascertained at room temperature. As soon as a big crystal is strongly heated the ions become movable. This can be proven by using conductivity measurements. In melt and solutions, the ions are quite movable electric conductivity results. Because sodium chloride has the very high melting temperature of 800°C, a mixture of lithium chloride and potassium chloride are molten together and used. 

Material Tripod and wire gauze, tripod and clamps, burner, two iron nails, cable wire, alligator clips, porcelain crucible, 9-V battery, glass beaker, graphite electrodes, multimeter (V and A), lamp rock salt crystal, lithium chloride, potassium chloride. 

Procedure (a) Firmly secure a rock salt crystal in between two iron nails on a wire gauze connect both nails to the 220 V or 110 V plug and with the multimeter (caution ). Strongly heat the crystal while observing the multimeter, (b) Make ready an electrical circuit of battery, multimeter, lamp and two 

Observation (a) The crystal does not conduct electricity at room temperature, but does so when strongly heated. Where the crystal touches the iron nails, one sees light flashes and color changes in the crystal, (b) Molten salts conduct electricity even at a voltage of 6 V the lamp light up, the multimeter shows certain electrical conductivity depending on the distance between the electrodes from each other, (c) Solutions of salt conduct electricity. 

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