A chemist wishes to determine the concentration of CrO4-2 ions electrochemically. A cell is constructed consisting of saturated calomel electrode (SCE) and a silver wire coated with Ag2CrO4. The SCE is composed of mercury in contact with a saturated solution of calomel (Hg2Cl2). The electrolyte solution in the half-cell is saturated KCl. The E°cell of the SCE half-cell is +0.242 V with respect to the standard hydrogen electrode. The half-reaction for the reduction of Ag2CrO4 is shown below.

Question

A chemist wishes to determine the concentration of CrO4-2 ions electrochemically. A cell is constructed consisting of saturated calomel electrode (SCE) and a silver wire coated with Ag2CrO4. The SCE is composed of mercury in contact with a saturated solution of calomel (Hg2Cl2). The electrolyte solution in the half-cell is saturated KCl. The E°cell of the SCE half-cell is +0.242 V with respect to the standard hydrogen electrode. The half-reaction for the reduction of Ag2CrO4 is shown below.

What would I have to put into the cell?

Answer 1

Jake--

Variations of this problem have been posted two or three times over the last few days and I still don't get what you are asking. I assume the half-reaction for the reduction of Ag2CrO4 is given. Can you please include that here? Second, "what would I put into the cell" where? Where are you being asked to put something? Third, you don't list a voltage for the complete set up. You can't calculate a concentration of anything without the cell potential.

Answer 2

To determine the concentration of CrO4-2 ions electrochemically using the given setup, you would need to construct a cell consisting of a saturated calomel electrode (SCE) and a silver wire coated with Ag2CrO4.

In the half-cell containing the SCE, you would need a mercury electrode in contact with a saturated solution of calomel (Hg2Cl2). The SCE serves as a reference electrode and helps maintain a constant potential. The electrolyte solution in the SCE half-cell is saturated KCl, which acts as the conducting medium.

In the other half-cell, you would place the silver wire coated with Ag2CrO4. The half-reaction for the reduction of Ag2CrO4 is given as:

Ag2CrO4 + 2e- -> 2Ag + CrO4-2

The silver wire coated with Ag2CrO4 acts as the working electrode where the reduction reaction occurs.

By connecting the two half-cells, you complete the electrochemical cell setup. The potential difference between the SCE and the working electrode can be measured to determine the concentration of CrO4-2 ions. The E°cell of the SCE half-cell is given as +0.242 V with respect to the standard hydrogen electrode, and this value can be considered during the measurement.

Note: It's important to handle mercury and calomel solutions with caution as they are toxic. Proper safety measures should be followed while working with them.