Page 1 CBSE TEST PAPER-03 CLASS - XII CHEMISTRY (Electrochemistry) [ANSWERS] Topic: - Conductance, Equivalent Conductance and Molar conductance 1. The resistively of a substance is its resistance when it is one meter long and its area of cross Section is one m 2 . 2. The SI unit of conductance is Siemens, denoted by the symbol, S & is equal to O -1 . 3. Conductivity of a material in Sm -1 is its conductance when it is 1m long and its area of cross - section is 1m 2 . It is represented by ? . 4. The conductivity of an electrolyte depends upon i) The nature of electrolyte added ii) Size of the ions produced and their solvation iii) Concentration of the electrolyte iv) Temperature 5. Molar conductance, O m is related to conductively by the relation. O m = k c Where ? = conductivity in s/m. C = concentration in mol/m 3 6. Cell constant and conductivity are related by the expression- ? = G R where G = Cell constant ? = conductivity R = Resistance. Page 2 CBSE TEST PAPER-03 CLASS - XII CHEMISTRY (Electrochemistry) [ANSWERS] Topic: - Conductance, Equivalent Conductance and Molar conductance 1. The resistively of a substance is its resistance when it is one meter long and its area of cross Section is one m 2 . 2. The SI unit of conductance is Siemens, denoted by the symbol, S & is equal to O -1 . 3. Conductivity of a material in Sm -1 is its conductance when it is 1m long and its area of cross - section is 1m 2 . It is represented by ? . 4. The conductivity of an electrolyte depends upon i) The nature of electrolyte added ii) Size of the ions produced and their solvation iii) Concentration of the electrolyte iv) Temperature 5. Molar conductance, O m is related to conductively by the relation. O m = k c Where ? = conductivity in s/m. C = concentration in mol/m 3 6. Cell constant and conductivity are related by the expression- ? = G R where G = Cell constant ? = conductivity R = Resistance. 7. Specific conductivity = cell constant Resistance Or cell constant = conductivity × Resistance = 92 -1 -1 cm 247.8 O × O = 22797.6 1 - O 8. 2 -1 = 1000 S cm mol m C ? ? × = 1000 M ? ? = 1000 m M ? × = 2 4.6 / 0.1m 100 S cm mol × = 0.00046 s/cm Resistivity = 1 ? = -1 1 = 2174 cm 0.00046 S cm O . 9. With increase in temperature, the K.E. of metal cation increases and obstructs the free flow of electrons decreasing the conducts of metal while in case of electrolytes, increased temperature increases the mobility of ions this increases the conductance of ions. 10. ? = 1.2 2/3 × 10 -3 -1 -1 cm O -1 2 -1 = 165.7 cm mol m ? O .Read More