there is no absolull be measu and the property endency, ured only relative to be
ID: 513299 • Letter: T
Question
there is no absolull be measu and the property endency, ured only relative to be alled the oxi potential, is measured in volts relative to the by the oxidative half idized. electrode defi (SHE) hydrogen standard Haug, P-1 bar) 2 H (ag, 1 M)+ 2e ential of zero (which being zero, is also the reduction potential, dation ed the oxi and is assign ated with the reverse reaction) Metals more easily oxidized than i,e. a sitive oxi dation potential, and metals less easily oxidized than hydrogen have hydrogen have po potential. A list of metals, like that shown in Fig. 1, beginning with the a negative oxi most withthe ve oxidation potential active, meaning least easily including most negati oxidation potential of zero is called the electromotive series hydrogen at assigned and elements are also included the list is called the electrochemical Metals in the electromotive series can be organized into categories based on reactivity with different reagents. One common scheme based on cold water, hot watersteam, aqueous acids (H,o and oxygen is shown in Fig 1. The most active metals can be oxidized by cold water to produce hydrogen (i.e., displace H2from water in reactions like Reacts with o, to form oxides Displace H, from acid Displace Hrfrom steam Displace Ha from water Ag Hg Pt Li K Ba Ca Na Mg Al Min zn Cr Fe cd Co Ni sn Pb H sb As B Least Active Most Active Fig. 1 Activity series of metals, H, is included for reference. The next category is somewhat less active and will displace hydrogen from water only at elevated temperature (i.ee, steam) in reactions like 217Explanation / Answer
According to the figure Cr is more active than Fe, thus , the corrosion normally takes up more TIME, that is, even though it will oxidize easier than Iron, this does not means it is faster.
One more other thing that there are plenty of other species added to the chrome layer but the basis of a very effective to prevent the corrosion is that of kinetics.
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