Q7E - Chemistry (OpenStax)

Question

Colourful fireworks often involve the decomposition of barium nitrate and potassium chlorate and the reaction of metals magnesium, aluminium, and iron with oxygen.

(a)Write the formulae of barium nitrate and potassium chlorate.

(b)The decomposition of solid potassium chlorate leads to the formation of solid potassium chloride and diatomic oxygen gas. Write an equation for the reaction.

(c) The decomposition of solid barium nitrate leads to the formation of solid barium oxide, diatomic nitrogen gas and diatomic oxygen gas. Write an equation for the reaction.

(d)Write separate equations for the reactions of the solid metals magnesium, aluminium and iron and oxygen gas to yield the corresponding metal oxides.(Assume the iron oxide contains \(F{e^{3 + }}\)ions.)

Step-by-Step Solution

Answer

(a) Formulae of barium nitrate and potassium chlorate:\(Ba{\left( {N{O_3}} \right)_2},KCl{O_3}\)

(b) Equation for decomposition of solid potassium chlorate:\(2KCl{O_3}\left( s \right) \to 2KCl\left( s \right) + 3{O_2}\left( g \right)\)

(c) Equation for decomposition of solid barium nitrate:\(2Ba{\left( {N{O_3}} \right)_2}\left( s \right) \to 2BaO\left( s \right) + 2{N_2}\left( g \right) + 5{O_2}\left( g \right)\)

(d)  Formation of metal oxides:

\(2Mg\left( s \right) + {O_2}\left( g \right) \to 2MgO\left( s \right)\)

\(4Al\left( s \right) + 3{O_2}\left( g \right) \to 2A{l_2}{O_3}\left( s \right)\)

\(4Fe\left( s \right) + 3{O_2}\left( g \right) \to 2F{e_2}{O_3}\left( s \right)\)

Step 1: Barium and potassium salts

The molecular formulae of barium nitrate,potassium chlorate are indicated by \(Ba{\left( {N{O_3}} \right)_2},KCl{O_3}\) respectively.

Step 2: Decomposition of potassium chlorate

Potassium chlorate decomposes,resulting inpotassium chloride and oxygen. The balanced equation is as follows:

\(2KCl{O_3}\left( s \right) \to 2KCl\left( s \right) + 3{O_2}\left( g \right)\)

Step 3: Decomposition of barium nitrate

The balanced equation for barium nitrate decomposition is as given below:

\(2Ba{\left( {N{O_3}} \right)_2}\left( s \right) \to 2BaO\left( s \right) + 2{N_2}\left( g \right) + 5{O_2}\left( g \right)\)

Step 4: Metal oxide formation

The balanced reactions of magnesium, aluminium and iron with oxygen, forming the corresponding oxides are represented as follows:

\(2Mg\left( s \right) + {O_2}\left( g \right) \to 2MgO\left( s \right)\)

\(4Al\left( s \right) + 3{O_2}\left( g \right) \to 2A{l_2}{O_3}\left( s \right)\)

\(4Fe\left( s \right) + 3{O_2}\left( g \right) \to 2F{e_2}{O_3}\left( s \right)\)