GAS-EVOLUTION REACTIONS
7) [tex]HCl (aq)[/tex] and [tex]Na_2S(aq)[/tex]
[tex]2 HCl (aq) + Na_2S(aq) \rightarrow H_2S_1(g)[/tex]
Molecular Equation
Complete Ionic Equation
Net Ionic Equation
Spectator Ions
Answer (2)
The complete ionic equation is obtained by dissociating aqueous species into ions: 2 H + ( a q ) + 2 C l − ( a q ) + 2 N a + ( a q ) + S 2 − ( a q ) → H 2 S ( g ) + 2 N a + ( a q ) + 2 C l − ( a q ) .
Spectator ions are identified as those present on both sides of the equation: N a + and C l − .
The net ionic equation is derived by removing spectator ions: 2 H + ( a q ) + S 2 − ( a q ) → H 2 S ( g ) .
The final answer consists of the complete ionic equation, net ionic equation, and the spectator ions.
Explanation
Problem Analysis We are given the molecular equation for the reaction between hydrochloric acid ( H Cl ) and sodium sulfide ( N a 2 S ) and asked to find the complete ionic equation, net ionic equation, and spectator ions.
Molecular Equation The molecular equation is: 2 H Cl ( a q ) + N a 2 S ( a q ) → H 2 S ( g ) + 2 N a Cl ( a q ) .
Complete Ionic Equation To write the complete ionic equation, we dissociate all aqueous species into their respective ions. Strong acids like H Cl completely dissociate in water. Soluble ionic compounds like N a 2 S and N a Cl also dissociate into ions. H 2 S is a gas and does not dissociate. Thus, the complete ionic equation is: 2 H + ( a q ) + 2 C l − ( a q ) + 2 N a + ( a q ) + S 2 − ( a q ) → H 2 S ( g ) + 2 N a + ( a q ) + 2 C l − ( a q ) .
Spectator Ions Spectator ions are those that appear on both sides of the complete ionic equation. In this case, N a + and C l − are spectator ions.
Net Ionic Equation To obtain the net ionic equation, we remove the spectator ions from the complete ionic equation: 2 H + ( a q ) + S 2 − ( a q ) → H 2 S ( g ) .
Final Answer Therefore, the complete ionic equation is 2 H + ( a q ) + 2 C l − ( a q ) + 2 N a + ( a q ) + S 2 − ( a q ) → H 2 S ( g ) + 2 N a + ( a q ) + 2 C l − ( a q ) , the net ionic equation is 2 H + ( a q ) + S 2 − ( a q ) → H 2 S ( g ) , and the spectator ions are N a + and C l − .
Examples
Gas evolution reactions are commonly used in various industrial processes, such as the production of certain chemicals or the removal of unwanted gases from a system. For example, the reaction between an acid and a carbonate produces carbon dioxide gas, which is used in the production of carbonated beverages and in fire extinguishers. Understanding the ionic and net ionic equations helps in optimizing these processes and predicting the outcome of similar reactions.
The complete ionic equation for the reaction between hydrochloric acid and sodium sulfide is 2 H + ( a q ) + 2 C l − ( a q ) + 2 N a + ( a q ) + S 2 − ( a q ) → H 2 S ( g ) + 2 N a + ( a q ) + 2 C l − ( a q ) . The net ionic equation is 2 H + ( a q ) + S 2 − ( a q ) → H 2 S ( g ) , and the spectator ions are N a + and C l − .
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