Question

Which of the following solutions have highest resistance? (a) \(1 \mathrm{~N}-\mathrm{NaCl}\) (b) \(0.05 \mathrm{~N}-\mathrm{NaCl}\) (c) \(2 \mathrm{~N}-\mathrm{NaCl}\) (d) \(0.1 \mathrm{~N}-\mathrm{NaCl}\)

Short answer

The solution with highest resistance is (b) 0.05 N-NaCl.

Step-by-step solution

Understand the Concept of Molar Conductivity

Resistance of an electrolytic solution is inversely related to its concentration. The higher the concentration of ions in the solution, the lower the resistance, because there are more charge carriers to transport electric current.

Compare the Concentrations

To find the solution with the highest resistance, look for the solution with the lowest concentration of ions, since resistance is inversely proportional to concentration.

Identify the Solution with the Lowest Concentration

Among the given options, the solution with the lowest concentration is (b) 0.05 N-NaCl.

Conclusion

The 0.05 N-NaCl solution has the highest resistance because it has the least concentration of ions.

Key concepts

Molar Conductivity

Molar conductivity, represented by the symbol \( \Lambda_m \), is a measure of how well an electrolyte can conduct electricity when dissolved in a solvent to form an electrolytic solution. It is defined as the conductivity of the solution divided by the molar concentration of the electrolyte. Molar conductivity increases with the dilution of the solution, because the ions present in the solution contribute more to the current as they are less likely to be surrounded by other ions, thus reducing inter-ionic attraction and allowing them to move more freely.

Molar conductivity is a critical parameter because it gives insight into the behavior of electrolytes in solutions, which is essential in fields like chemistry, biology, and materials science. Understanding molar conductivity helps us grasp why some electrolytic solutions conduct electricity better than others and how electrolytes can be optimized for various applications, such as in batteries or electroplating.

Ionic Concentration

Ionic concentration refers to the amount of ions present in a solution and is often measured in normality (N), which is the number of equivalents of solute per liter of solution. In the context of resistance in electrochemistry, the ionic concentration plays a pivotal role. A higher concentration of ions implies more charge carriers are available to move and conduct electric current, thereby leading to lower resistance. Conversely, lower ionic concentrations result in fewer charge carriers and, subsequently, higher resistance.

It is important to note that while concentration and molarity can be interchanged in certain circumstances, the type of ion in the solution must also be considered, as its size and charge also affect how easily it can move through the solution. Such factors are crucial when optimizing electrolyte solutions for specific applications or when predicting and controlling the behavior of electrochemical reactions.

Electrochemistry

Electrochemistry explores the relationship between electrical energy and chemical reactions. It is a branch of chemistry that studies how electrons can be used to create chemical change, or conversely, how chemical reactions can generate electric current. In the case of an electrolytic solution, electrochemistry involves the movement of ions within the solution to facilitate the transfer of electrons from one chemical species to another.

Understanding the principles of electrochemistry is fundamental to industries and technologies that rely on batteries, fuel cells, corrosion protection, and the electroplating of metals. Through the application of electric current, we can induce desirable chemical changes, such as the refinement of metals or the production of materials with specific properties. Electrochemistry is not only about currents and voltages but encompasses thermodynamic factors, kinetics, and, as we've seen, the importance of solutions' properties like molar conductivity and ionic concentration.

Transport of Electric Current

The transport of electric current in an electrolytic solution is facilitated by the movement of charged particles, namely ions. This movement is essential for the functioning of various electrochemical cells and devices. The ease with which this current transport occurs depends on several factors, including the type and concentration of ions, the temperature, and the presence of a potential difference (voltage) applied across the solution.

In a typical electrolytic cell, cations (positively charged ions) migrate to the cathode (negative electrode), and anions (negatively charged ions) move toward the anode (positive electrode), completing the circuit and allowing the current to flow. The resistance to this current flow is directly related to the ionic concentration—the more dilute the solution, meaning the fewer ions available to move, the higher the resistance. This concept is crucial for anyone working with or designing systems that rely on the electrolytic transport of electricity, as optimizing ionic movement is key to efficiency and effectiveness.