Question
(a) The table below shows the standard reduction potentials for four half cells Study it and answer the questions that follow. Number Half-reaction Evolts I Ag_((aq))^++2e^-leftharpoons Ag_((s)) +0.80 II Cu^2+_((aq))+2e^-=Cu_((s)) +0.34 III Pb^2+_((aq))+2e^-leftharpoons Pb_((s)) -0.13 N Zn^2+_(aq))+2e^2+Zn_((s)) -0.76 (i) - Identify the strongest reducing agent (1 mark) __ Predict whether or not a solution of copper (II) nitrate can be stored d in a container made of lead (2 marks) __ In the space provided draw a labeled diagram of the electrochemical cell that would give the hest emf. (3 marks) (iv) Calculate the E'' of the electrochemical cell constructed in (iii) above (1 mark)
Answer
4.4
(248 Votes)
Mason
Professional · Tutor for 6 years
Answer
(i) The strongest reducing agent is the one with the most negative reduction potential. From the table, the half-reaction with the most negative reduction potential is the one for zinc (Zn), which is -0.76 V. Therefore, Zn is the strongest reducing agent.(ii) To predict whether a solution of copper (II) nitrate can be stored in a container made of lead, we need to compare the standard reduction potentials of the two metals. The standard reduction potential of lead (Pb) is -0.13 V, while the standard reduction potential of copper (Cu) is +0.34 V. Since the standard reduction potential of copper is more positive than that of lead, copper is more reactive than lead. Therefore, a solution of copper (II) nitrate can be stored in a container made of lead without any reaction occurring.(iii) To draw a labeled diagram of the electrochemical cell that would give the highest emf, we need to connect the half-reactions with the most positive and most negative reduction potentials. In this case, the half-reaction with the most positive reduction potential is copper (Cu), and the half-reaction with the most negative reduction potential is zinc (Zn). Therefore, we would connect the copper half-reaction to the cathode and the zinc half-reaction to the anode.(iv) To calculate the emf of the electrochemical cell, we need to sum up the standard reduction potentials of the two half-reactions. The standard reduction potential of the copper half-reaction is +0.34 V, and the standard reduction potential of the zinc half-reaction is -0.76 V. Therefore, the emf of the electrochemical cell is +0.34 V - 0.76 V = -0.42 V.