By means of ion/electron part equations, write fully balanced equations for the following reaction: the production of hydrogen by the action of hydrochloric acid on magnesium.
I'm so confused as to why Cl, because it says hydrochloric acid, is not used as part of any of the two half equations.
Mg → Mg2+ + 2e- and 2H+ + 2e– → H2 are the only two I need according to the answers to solve. Any explanation for this would be greatly appreciated.
You have written fully balanced equations for the oxidation half and the reduction half. The reason Cl doesn't show up is because it is neither oxidized nor reduced. The balanced molecular equation would be
Mg + 2HCl ==> MgCl2 + H2. The Cl^- is called a spectator ion because it never enters into the reaction. It's there just to balance the charges. You can't add H^+. H^+ must be added by using HCl, HBr, HF, etc In each case the Cl^-, Br^- and F^- are spectator ions.
Ohh that makes more sense. Thanks
In the reaction between hydrochloric acid (HCl) and magnesium (Mg), the hydrogen gas (H2) is produced. The balanced equation for this reaction is:
Mg + 2HCl → MgCl2 + H2
Now, let's break down the reaction into half-equations to understand the role of each species:
1. The oxidation half-equation involves the loss of electrons from magnesium to form magnesium ions:
Mg → Mg2+ + 2eˉ
In this half-equation, magnesium (Mg) loses two electrons (2eˉ) to become a magnesium ion with a 2+ charge (Mg2+). The electrons on the right side of the equation represent the electrons lost by magnesium during oxidation.
2. The reduction half-equation involves the gain of electrons by hydrogen ions to form hydrogen gas:
2H+ + 2eˉ → H2
In this half-equation, two hydrogen ions (2H+) gain two electrons (2eˉ) to form hydrogen gas (H2). The electrons on the left side of the equation represent the electrons gained by the hydrogen ions during reduction.
Combining these two half-equations together, we can see that the magnesium atoms lose electrons, and these electrons are gained by the hydrogen ions to form hydrogen gas. Chlorine (Cl) is not directly involved in these half-equations because it remains in its ionic form as chloride ions (Clˉ) in the magnesium chloride (MgCl2) product.
I hope this explanation clarifies why chlorine (Cl) is not explicitly included in the half-equations for the production of hydrogen by the reaction of hydrochloric acid with magnesium.