Question

Write chemical equations for the following reactions:
${\rm I})$ Reaction between gallium $({\rm I}{\rm I}{\rm I})$ oxide and dilute nitric acid to form salt and water only.
${\rm I}{\rm I})$ Reaction between gallium $({\rm I}{\rm I}{\rm I})$ oxide and sodium hydroxide solution forms only water and a salt containing the negative ion $G{a_2}{O_4}^{2 - }$

Answer 1

Hint:Find out the charge on Gallium in the given reactants. Both the reactions are displacement reactions so the Oxygen in gallium $({\rm I}{\rm I}{\rm I})$ oxide is replaced by another element from the second reactant. One of the products is already given as water so the salt can be found accordingly.

Complete answer:
${\rm I})$ In this reaction, gallium $({\rm I}{\rm I}{\rm I})$ oxide and dilute nitric acid are given to us as reactants and the products are a salt and water. If we consider the unknown salt to be $X$ then the equation would be
$G{a_2}{O_3} + HN{O_3} \to X + {H_2}O$
Now, from this equation we know that the charge on Gallium is \[ + 3\] and hence we can conclude that $X$ is $Ga{\left( {N{O_3}} \right)_3}$ and the equation would be
$G{a_2}{O_3} + HN{O_3} \to Ga{\left( {N{O_3}} \right)_3} + {H_2}O$
Balancing the equation:
$G{a_2}{O_3} + 6HN{O_3} \to 2Ga{\left( {N{O_3}} \right)_3} + 3{H_2}O$

${\rm I}{\rm I})$ The reactants given to us are $G{a_2}{O_3}$ and $NaOH$ and the products are water and a salt containing $G{a_2}{O_4}^{2 - }$ , let us consider the unknown salt to be $X$
$G{a_2}{O_3} + NaOH \to X + {H_2}O$
From the given information we can say that the salt is $N{a_2}G{a_2}{O_4}$ since it is a displacement reaction.
The equation would become $G{a_2}{O_3} + NaOH \to N{a_2}G{a_2}{O_4} + {H_2}O$
Balanced equation is given as \[G{a_2}{O_3} + 2NaOH \to 2NaGa{O_2} + {H_2}O\]

Additional Information:
Gallium $({\rm I}{\rm I}{\rm I})$ trioxide is an inorganic compound with the formula $G{a_2}{O_3}$ . It is an amphoteric substance and also dissolves in strong alkali. It is studied in the use of phosphors, lasers, luminescent materials etc.

Note:
The charge on gallium in the given reactants is three. Hence during the displacement reaction, the three oxygen atoms attached to gallium are replaced with the ions of other given reactant molecules forming water molecules and a salt as products.