A brass and unknown metallic material were placed in aerated $\%3\mathrm{.}5$NaCl solution

until steady$-$state corrosion potentials were reached. Then they were coupled with conductive

wire. Measured galvanic currents are given in the table below.

a$)$ Identify the unknown material, by using the Ecorr datas and the series of galvanic chart, and

predict the corrosion potential of unknown material

b$)$ Which material did corrode in galvanic couple? Why?

c$)$ Calculate corrosion current density in galvanic couple as a function of Ac$/$Aa ratio. How

would the corrosion rate will change as a function of Ac$/$Aa ratio? Answer without

calculation of the corrosion rate$)$

d$)$ Explain the results in the part $($b$)$ by schematically drawing the E vs$.$ Log I before and

after galvanic coupling for your system. Show $E_{\text{C}\text{o}\text{r}}$ and $E_{\text{G}\text{a}\text{l}\text{.}\text{C}\text{o}\text{r}}$ values on the graph with

corrosion currents for uncouple materials and couple materials.

e$)$ For your galvanic couple, indicate the possible oxidation $($anodic$)$ and reduction

$($cathodic$)$ reactions before and after connecting $($galvanic coupling$).$ Where are the major

anodic and cathodic reactions taking place after galvanic coupling?

E Cor$-$Brass $=-0\mathrm{.}227V$ Delta Cor$-$Brass $-$ E Cor$-$X