In: Chemistry
Consider the reaction
Mg(s)+Fe2+(aq)→Mg2+(aq)+Fe(s)
at 69 ∘C , where [Fe2+]= 3.10 M and [Mg2+]= 0.110 M .
a)What is the value for the reaction quotient, Q, for the cell?
b) What is the value for the temperature, T, in kelvins?
c) What is the value for n?
d) Calculate the standard cell potential for Mg(s)+Fe2+(aq)→Mg2+(aq)+Fe(s)
a) reaction quotient( Q ) = concentrations of products / concentrations of reactants
= [Mg+2] / [Fe+2]
= 0.110 / 3.10
= 0.0355
b) temperature in Kelvin = T + 273
= 69 + 273
= 342 K
c) value of n = 2
number of moles of electrons are trasfered = 2 from Mg to Fe+2
d) the standard cell potential = 1.94 V
explanation:
anode reaction: oxidation takes place
Mg(s) -------------------------> Mg+2 (aq) + 2e- , E0Mg+2/Mg = - 2.38 V
cathode reaction : reduction takes palce
Fe+2(aq) + 2e- -----------------------------> Fe(s) , E0Fe+2/Fe = -0.44V
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net reaction: Mg(s) +Fe+2(aq) -------------------------> Mg+2 (aq) + Fe(s)
E0cell= E0cathode- E0anode
E0cell= E0Fe+2/Fe - E0Mg+2/Mg
= -0.44 - (-2.38)
= 1.94 V