n 1: Determining if an electrochemical cell is in the standard state ion 1 onsid

Question

n 1: Determining if an electrochemical cell is in the standard state ion 1 onsider this... In thermodynamics, the Standard State of a material is a reference point used to calculate the material's properties. A gas in the standard state has a pressure of 1 bar and is at 25°C, and the standard state of solids and liquids is the pure form at 1 bar and 25°C. Solutions are in the standard state when they have an activity of 1 M at 25°C. Remember A-|Mly, where A is the activity and is the activity coefficient. In analytica electrochemistry, concentrations of analyte are often in the millimolar range, but supporting e concentrations may be high enough for activity coefficients to deviate from 1. For purposes ct we will make the approximation that activities are equal to concentrations. lectrolyte this activity. Figure 1 Electrochemical apparatus All of these apparatuses contain a zine electrode and a silver electrode mical apparatuses with varying concentrations and connections. KNO, salt bridge bridge Ag Zn Ag Zn I M 1 M 13x10 M 2.5x10 MU bridge Ag KNo KNO, salt bridge Zn Ag 1 M IM U 13x10 M 2.5x 104 MU

Explanation / Answer

Q1) Standard state

    For gases    P= 1 atm , T= 25o C

   For solids and pure liquids P = 1 bar, T= 25o C

For solutions concentration =1M   at T= 25o C

Q2) The apparatuses A and C

Q3) Lisiting

A - Zn rod , Ag rod , zinc nitrate solution, silver nitrate solution, KNO3 salt bridge and a bulb

B - Zn rod , Ag rod , zinc nitrate solution, silver nitrate solution, KNO3 salt bridge and a bulb

C - Zn rod , Ag rod , zinc nitrate solution, silver nitrate solution and KNO3 salt bridge

D - Zn rod , Ag rod , zinc nitrate solution, silver nitrate solution and a bulb

Q4) A and B apparatus only fulfil the criterion of electrochemical cell as they have completed electrical circuits.

Q5) C and D are not electrochemical cells as the circuit is not completed (one has no salt bridge , other no bulb).

Q6)For cell A

Cell reaction is Zn +2 Ag+ ---à 2Ag + Zn+2

The two half cell reactions are

   Zn ----à Zn+2 ( oxidation)

2 Ag+ -----à 2 Ag (reduction)

The flow current is from Ag to Zinc as the electrons flow from zinc to silver through the wire.

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