please show clear answer Consider the gas phase reaction A+ 3B = 2C. To maximize
ID: 1071253 • Letter: P
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please show clear answer
Consider the gas phase reaction A+ 3B = 2C. To maximize the production of C, should you increase or decrease the overall pressure? Explain your answer. True or False? If we double all the coefficients in an electrochemical cell's overall reaction, charge number N is doubled but the cell's potential is unchanged. If the answer is false, explain why. If an acid is held at a fixed distance away from a positively charged surface, will it be stronger or weaker than in the absence of the charged surface? Explain your answer. True or false? When an electrochemical half reaction is multiplied by 2, its standard reduction potential is multiplied by 2. If the answer is false, explain why.Explanation / Answer
a) The gas phase reaction is
A + 3 B = 2 C
Assuming the system to be in equilibrium, write down the equilibrium constant as
KP = PC2/(PA).(PB)3
where KP is the pressure equilibrium constant and PA, PB,PC denote partial pressures of the gaseous components.
The partial pressures are related to the total pressure of the system P as
PA = xA.P where xA = nA/n where xA = mole fraction of A in the gaseous system = ratio of the number of moles of A to the total number of moles of gaseous components in the system.
Similarly, PB = xB.P
and PC = xC.P
Again, express Kp in terms of P:
KP = (xc.P)2/(xA.P).(xB.P)3 = (xC2/xA.xB3).(P)2-1-3 = (xC2/xA.xB3).(1/P2)
KP is inversely proportional to P2. Hence, when P is decreased, the numerator increases and hence the forward reaction is favoured. Therefore, the maximize the production of C, the total pressure must be reduced.
b) The cell potential remains unchanged as well as the charge number, N and hence the statement is false. Multiplying the co-efficients in the electrochemical cell’s reaction does not change the charge number. The charge number is the quantized value of the electric charge which remains unchanged for an ion even when the co-efficients are doubled.
d) The given statement is false. The standard reduction potential remains unchanged. This is because electrochemical potential is an intensive protperty, i.e., independent of the mass or number of moles of reactants participating in the reaction. The electrochemical potential is defined in unit of V = Joule/Coulomb = Energy/Charge. Both energy and charge are extensive properties, thus multiplying the half reaction by 2 doubles both the energy and the charge involved with the reaction; however the ratio, cell potential, remains unchanged.
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