Question

9 multiple choice 1 point
one of the most basic and practical precipitation reactions occurs between table salt (nacl) and water. what is the molecular equation for this reaction?
nacl + h₂o → naoh + hcl
nacl + h₂o → nah + cloh
nacl + h₂o → nao + h₂ocl
nacl + h₂o → nacl + h₂oh
10 multiple choice 1 point
mg₍ₛ₎ + 2h⁺₍ₐq₎ + 2cl⁻₍ₐq₎ → mg²⁺₍ₐq₎ + 2cl⁻₍ₐq₎ + h₂₍g₎
this is an example of a...
general exchange equation.
net ionic equation.
molecular equation.
complete ionic equation.

Explanation:

Question 9

Step1: Recall precipitation reaction of NaCl and H₂O

NaCl (sodium chloride) dissolves in water, but the reaction here is a hydrolysis - like reaction. The correct reaction is the dissociation and potential reaction where NaCl + H₂O can be thought of as producing NaOH and HCl (even though in reality, NaCl is a neutral salt and its hydrolysis is very weak, but among the given options, this is the only one that follows the rules of chemical bonding and reaction products).

Step2: Analyze each option

• Option 1: \(NaCl + H_2O

ightarrow NaOH + HCl\) - This reaction shows the ions (Na⁺, Cl⁻ from NaCl and H⁺, OH⁻ from H₂O) potentially recombining to form NaOH and HCl.

• Option 2: \(NaCl + H_2O

ightarrow NaH + ClOH\) - NaH and ClOH are not the correct products from NaCl and H₂O reaction. NaH is a strong reducing agent and not formed in this reaction, and ClOH is not a common or correct product here.

• Option 3: \(NaCl + H_2O

ightarrow NaO + H_2OCl\) - NaO is not a stable compound in this context, and H₂OCl is not a valid product.

• Option 4: \(NaCl + H_2O

ightarrow NaCl + H_2OH\) - H₂OH is not a valid chemical species.

Step1: Recall types of chemical equations

• General exchange equation: Not a standard type of chemical equation for this context.
• Net ionic equation: Shows only the species that actually participate in the reaction, with spectator ions removed.
• Molecular equation: Shows the reactants and products as neutral molecules (even if they are ionic compounds in solution).
• Complete ionic equation: Shows all the ions present in the reaction mixture, including spectator ions.

Step2: Analyze the given equation \(Mg_{(s)} + 2H^+_{(aq)} + 2Cl^-_{(aq)}

ightarrow Mg^{2+}_{(aq)} + 2Cl^-_{(aq)} + H_2_{(g)}\)
In this equation, the \(Cl^-\) ions are present on both sides (spectator ions) and the equation shows the species that are actually reacting (Mg, \(H^+\)) and the products ( \(Mg^{2+}\), \(H_2\)) with spectator ions included. This is a complete ionic equation? Wait, no. Wait, the net ionic equation would remove the spectator ions (\(Cl^-\)). Wait, no, let's re - check.

Wait, the given equation has \(Cl^-\) on both sides. The complete ionic equation includes all ions, and the net ionic equation removes the spectator ions. But in this equation, we have \(Mg(s)\) (a solid), \(H^+(aq)\), \(Cl^-(aq)\) on the left and \(Mg^{2+}(aq)\), \(Cl^-(aq)\), \(H_2(g)\) on the right. If we remove the \(Cl^-\) (spectator ions), the net ionic equation would be \(Mg(s)+2H^+(aq)
ightarrow Mg^{2+}(aq)+H_2(g)\). But the given equation includes the spectator ions (\(Cl^-\)), so it is a complete ionic equation? Wait, no, the options are: general exchange, net ionic, molecular, complete ionic.

Wait, the given equation: \(Mg_{(s)} + 2H^+_{(aq)} + 2Cl^-_{(aq)}
ightarrow Mg^{2+}_{(aq)} + 2Cl^-_{(aq)} + H_2_{(g)}\)

A complete ionic equation shows all the ions (including spectator ions) in the reaction. Here, \(Cl^-\) is a spectator ion (same on both sides), and the equation shows all the ions ( \(H^+\), \(Cl^-\), \(Mg^{2+}\)) along with the solid Mg and gaseous \(H_2\). Wait, but let's check the options again.

Wait, the net ionic equation would be \(Mg(s)+2H^+(aq)
ightarrow Mg^{2+}(aq)+H_2(g)\) (removing \(Cl^-\)). The complete ionic equation includes all ions, so the given equation is a complete ionic equation? Wait, no, the options:

• General exchange equation: Not relevant.
• Net ionic equation: No, because it includes spectator ions (\(Cl^-\)).
• Molecular equation: No, because it shows ions, not neutral molecules.
• Complete ionic equation: Yes, because it shows all the ions present in the solution (including spectator ions) along with the non - ionic species (Mg(s) and \(H_2(g)\)).

Wait, but let's re - examine the definitions:

• Molecular equation: Balanced chemical equation showing the reactants and products as molecules (e.g., \(Mg + 2HCl

ightarrow MgCl_2+H_2\)).

• Complete ionic equation: Shows all soluble ionic compounds as dissociated ions (e.g., \(Mg(s)+2H^+(aq)+2Cl^-(aq)

ightarrow Mg^{2+}(aq)+2Cl^-(aq)+H_2(g)\)) - this is the given equation.

• Net ionic equation: Removes spectator ions (e.g., \(Mg(s)+2H^+(aq)

ightarrow Mg^{2+}(aq)+H_2(g)\)).

So the given equation is a complete ionic equation.

Answer:

A. \(NaCl + H_2O
ightarrow NaOH + HCl\)

Question 10