Question

Using the cell described in Q1, a student determined the resistance of a 0.086 M KCl solution to be 20.4 Ohms. Calculate the molar conductance of this solution.

Answer 1

To calculate the molar conductance of a KCl solution, one needs to determine the solution's conductivity using the resistance and the cell constant, and then apply the molar conductance formula. The resistance is given, but without knowing the cell constant, the molar conductance cannot be calculated.

Step-by-step explanation:

To calculate the molar conductance of a 0.086 M KCl solution, given a resistance of 20.4 Ohms, we use the formula for molar conductance, which is Λm = (K * 1000) / M, where Λm is the molar conductance, K is the conductivity of the solution, M is the molarity of the solution, and 1000 is the factor to convert from S*cm²/mol to S*m²/mol. However, we first need to find the conductivity (K), which can be obtained from the resistance (R) using the formula K = 1/R, as long as the cell constant (G*) is known.

Since the cell constant is not provided, we cannot proceed with the calculation. Normally, the resistance R and the cell constant G* (geometry of the electrodes and distance between them) are used to find the conductivity K: K = G* / R. Then, with the conductivity K, we would calculate the molar conductance Λm. Without the cell constant, the molar conductance cannot be calculated.

Answer 2

To calculate the molar conductance of the 0.086 M KCl solution, divide the solution's molarity by the resistivity.

Step-by-step explanation:

To calculate the molar conductance of the 0.086 M KCl solution, we need to first determine the resistance per unit length of the solution. The resistance of the solution, 20.4 Ohms, is measured for a particular length. Let's assume the length of the cell is 'l'.

Using Ohm's Law (R = σL/A), where R is the resistance, σ is the resistivity, L is the length, and A is the cross-sectional area, we can rearrange the formula to solve for the resistivity: σ = R * A / l.

Knowing the resistivity, we can calculate the molar conductance by dividing the solution's molar concentration by the resistivity: Molar conductance = Molarity / Resistivity.