Temperature increases the rate of almost all chemical reactions. Figure 2-11 illustrates two common observations on the effect of temperature on the corrosion rates of metals. Curve A represents the behavior noted above , a very rapid or exponential rise in corrosion rate with increasing temperature. Behavior such as noted in curve B is also quite frequently observed. That is, an almost negligible temperature effect is followed by a very rapid rise in corrosion rate at higher temperature. Increasing the temperature of nitric acid, this effect is readily explained. Increasing the temperature of nitric acid greatly increases its oxidizing power. At low or moderate temperature, stainless steels exposed to nitric acid are in the passive state very close to the transpassive region. Hence, an increase in oxidizing power causes a very rapid increase in the corrosion rate of these materials. A similar sort of mechanism may explain the behavior of monel and nickel, as noted in Fig. 2-11 .However, it is possible that curves such as B in many instances erroneously represent actual behavior .It the corrosion rate at low temperature is very low and increases exponentially , linear plots will appear as curve b. that is, corrosion rate increases rapidly with temperature this is not evident in the usual plots of corrosion rate versus temperature because of the choice of scales.