Question
How does a metal react with water?
✓
Answer
Sodium and potassium react vigorously with water to evolve hydrogen. Calcium reacts with water slowly and less vigorously to evolve hydrogen and the metal floats on water. Magnesium reacts with hot water to evolve hydrogen. Aluminium, iron and zinc do not react with cold or hot water but they react with steam to evolve their oxides and hydrogen.
$2 Na _{( s )}+2 H _2 O _{( l )} \rightarrow 2 NaOH _{( aq )}+ H _{2( g )}+\text { heat energy }$
$2 K _{( s )}+2 H _2 O _{( l )} \rightarrow 2 KOH _{( aq )}+ H _{2( g )}+\text { heat energy }$
$2 Ca _{( s )}+2 H _2 O _{( l )} \rightarrow 2 Ca ( OH )_{2( aq )}+ H _{2( g )}$
$Mg _{( s )}+2 H _2 O _{( hot )} \rightarrow Mg \left( OH _{2( aq )}+ H _{2( g )}\right.$
$2 Al _{( s )}+3 H _2 O _{\text {steam }} \rightarrow Al _2 O _{3( s )}+3 H _{2( g )}$
$3 Fe _{( s )}+4 H _2 O _{\text {steam }} \rightarrow Fe _3 O _4+4 H _{2( g )}$
$Zn _{( s )}+ H _2 O _{\text {steam }} \rightarrow ZnO _{( s )}+ H _{2( g )}$
$2 Na _{( s )}+2 H _2 O _{( l )} \rightarrow 2 NaOH _{( aq )}+ H _{2( g )}+\text { heat energy }$
$2 K _{( s )}+2 H _2 O _{( l )} \rightarrow 2 KOH _{( aq )}+ H _{2( g )}+\text { heat energy }$
$2 Ca _{( s )}+2 H _2 O _{( l )} \rightarrow 2 Ca ( OH )_{2( aq )}+ H _{2( g )}$
$Mg _{( s )}+2 H _2 O _{( hot )} \rightarrow Mg \left( OH _{2( aq )}+ H _{2( g )}\right.$
$2 Al _{( s )}+3 H _2 O _{\text {steam }} \rightarrow Al _2 O _{3( s )}+3 H _{2( g )}$
$3 Fe _{( s )}+4 H _2 O _{\text {steam }} \rightarrow Fe _3 O _4+4 H _{2( g )}$
$Zn _{( s )}+ H _2 O _{\text {steam }} \rightarrow ZnO _{( s )}+ H _{2( g )}$
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