Answer:
The value is 
Explanation:
From the question we are told that
The equation is 
The temperature is ![T = 25^oC = 298 K [room \ temperature ]](https://tex.z-dn.net/?f=%20T%20%3D%2025%5EoC%20%3D%20%20298%20K%20%20%20%5Broom%20%20%5C%20temperature%20%5D)
The emf at standard condition is 
Generally at the cathode

At the anode

Generally for an electrochemical reaction, at room temperature the Gibbs free energy is mathematically represented as

Here n is the no of electron with value n = 6
F is the Faraday's constant with value 96487 J/V
=>
=> 
This Gibbs free energy can also be represented mathematically as

Here R is the cell constant with value 8.314J/K
K is the equilibrium constant
From above
=> 
Generally antilog = 2.718
=>
=> 
Answer:
29.98kg
Explanation:
12.0 gallons * (3.78541178 liters/gallon) * (1000 mL/liter) * (0.66 g/mL) * (1 kg/1000 g) = 29.98 kg
T = 20 % : 20 / 100 = 0.2
m1 = solute
m2 = Solvent
T = m1 / m1 + m2
0.2 = 500 g / 500 g + m2
0.2 * ( 500 + m2 ) = 500
0.2 * 500 + 0.2 m2 = 500
100 + 0.2 m2 = 500
0.2 m2 = 500 - 100
0.2 m2 = 400
m2 = 400 / 0.2
m2 = 2000 g of water
hope this helps!