v  When liquid state of water reacts with a metal it forms metal hydroxide and liberate out hydrogen gas but when the same water is evaporated then metals form metal oxides and liberate out hydrogen gas. Why is this difference in the products so created?

Asked by tultuldutta58 | 16th Oct, 2017, 10:23: PM

Expert Answer:

Product formation depends on the reactivity of the metals whether they will react with cold water, hot water, steam or will not react with water in any form at all.
More reactive metals like sodium and magnesium can react with simply water to form hydroxide because in solutions their hydroxides are stable (they are strongly basic in nature), while metals with lower reactivity (relatively lower reactive than sodium and magnesium) like iron react only with steam to first produce hydroxide which is not thermally stable and hence breaks down into iron oxide and water. 
Thus, reactivity of metals, stability of products formed, rate of reaction, heat of reaction along with physical form of water are the responsible factors for the formation of oxide or hydroxide formation. 

Answered by Prachi Sawant | 17th Oct, 2017, 09:40: AM