1. Calculate the standard stat emf, fancy E, change in G, and K at 25 degrees celcus for the following reaction
2Na(s) + 2H20(l) --------- 2NaOH(aq) + H2(g)
standard reduction potentals:
Na(positive 1) + e- ---------Na -2.71V
2H20 + 2e- ------------H2 + 2OH- - .83V
3. Draw a complete galvanic cell in which the electrodes are a nickel bar dipping into a 0.100M solution of Ni(positive 2) and a manganese bar dipping inot a 0.500 M soulution of Mn(positive 2). Label all the parts of the cell and indicate the direction of electron flow. Write a balanced eqation of the cell reaction and calculate the emf and fancy E for the cell
Standare reduction potentials:
Ni/Ni(positive 2) = -0.25 V Mn/Mn(positive 2) = -1.18V
4. Balance the following redox equations
Cr2O7(negative 2)(aq) + I2(aq)--------- Cr (positive 3) + IO3(negative 1)(aq)
HS2O3(negative 1)(aq)---------- S(s) + HSO4(negative 1) (aq) (acidic solution)© BrainMass Inc. brainmass.com October 24, 2018, 7:13 pm ad1c9bdddf
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1. 2Na(s) + 2H20(l) 2NaOH(aq) + H2(g)
Standard reduction potentials:
Na+ + e- Na; -2.71V
2H20 + 2e- H2 + 2OH-; -0.83V
E = 2.71*2 - 0.83 = 4.59 V
Free energy ΔGº = -nFEºcell, wheren is the number of moles of electrons transferred
F is Faraday's constant and represents the charge of one mole of electrons = 96,500 coulombs/mol
Here, ΔGº = -2*96,500*4.59 = 885.87 KJ
Equilibrium Constant: Kc = enFEº/RT = exp(885870/(8.31*298)) = exp(31767661)
2. What mass of Pb would be deposited by electrolysis of and aqueous solution of lead (II) nitrate using a current of 100 amps of 8.00 hours?
The reduction of Pb2+ ions will occur according to the following equation:
Pb2+(aq) + 2e- ...
It provides examples of solving electrochemistry questions.
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