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Electrochemistry — Chemistry STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceChemistryElectrochemistry3 Marks
Question
Classification of solid based on conductivity
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Answer

→ Materials are classified into conductors, insulators and semiconductors depending on the magnitude of their conductivity.
→ Metals and their alloys have very high conductivity and are known as conductors.
→ Certain non-metals like carbon-black, graphite and some organic polymers* are also possess electronically conductivity.
→ Substances like glass, ceramics, etc., having very low conductivity are known as insulators.
→ Substance like silicon, doped silicon and gallium arsenide having conductivity between conductors and insulators are called semiconductors and are important electronic materials.
→ Certain material called superconductors exhibit zero resistivity or infinite conductivity.
→ Earlier, only metals and their alloys at very low temperatures (0 to 15 K) were known to behave as superconductors, but now days a number of ceramic materials and mixed oxides are also known to show superconductivity at temperatures as high as 150 K.
→ The values of Conductivity of some Selected Materials at 298.15 K are given below.
MaterialConductivity/S$m ^{-1}$MaterialConductivity/S$m ^{-1}$
Conductors Aqueous Solution
Sodium$2.1 \times 10^3$Pure water$3.5 \times 10^{-5}$
Copper$5.9 \times 10^3$0.1 M HCl3.91
Silver$6.2 \times 10^3$0.01 M KCI0.14
Gold$4.5 \times 10^3$0.01M NaCl0.12
Iron$1.0 \times 10^3$0.1 M HAc0.047
Graphite$1.2 \times 10$0.01M HAc0.016
Insulators Semiconductors
Glass$1.0 \times 10^{-16}$CuO$1 \times 10^{-7}$
Teflon$1.0 \times 10^{-18}$Si$1.5 \times 10^{-2}$

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