Production of Hydrogen: Videos & Practice Problems

In the reaction between solid lithium hydride (LiH) and hydrofluoric acid (HF), we can identify the products by breaking down the reactants into their respective ions. Lithium (Li) is a Group 1A element, which means it has a +1 charge, while hydride (H^-) carries a -1 charge. Hydrofluoric acid dissociates into hydrogen ions (H⁺) and fluoride ions (F^-).

This reaction is classified as a double displacement reaction, where the hydrogen ions from the acid combine with the hydride ions to form hydrogen gas (H₂), while lithium ions combine with fluoride ions to produce lithium fluoride (LiF) in aqueous solution.

To ensure the reaction is balanced, we analyze the number of each type of atom on both sides of the equation. Initially, we have:

• 1 lithium (Li) on each side
• 2 hydrogens (H) on each side (1 from LiH and 1 from HF)
• 1 fluorine (F) on each side

Since the number of each atom is equal on both sides, the balanced chemical equation for this reaction is:

LiH (s) + HF (aq) → H₂ (g) + LiF (aq)

When reactive metals interact with acids such as sulfuric acid or hydrochloric acid, a chemical reaction occurs that results in the production of hydrogen gas (H₂). In this process, the metal is oxidized, meaning it loses electrons and is converted into metal ions. For instance, when a solid metal from Group 1A (alkali metals) reacts with the acid, it releases hydrogen ions (H⁺) from the acid solution.

The general reaction can be represented as follows:

Metal (s) + Acid (aq) → Metalⁿ⁺ (aq) + H₂ (g)

In this reaction, the metal ionizes, typically forming a +1 charge if it is from Group 1A. To balance the equation, it is important to account for the number of hydrogen atoms produced. Since two hydrogen ions are released for every molecule of hydrogen gas formed, a coefficient of 2 is placed in front of the H⁺ in the reactants. This ensures that the number of hydrogen atoms is equal on both sides of the equation.

Thus, the balanced equation for the reaction of a Group 1A metal with an acid can be expressed as:

2 H⁺ (aq) + Metal (s) → Metal⁺¹ (aq) + H₂ (g)

This reaction illustrates the oxidation of the metal and the generation of hydrogen gas as a significant product, showcasing the reactivity of metals with acids.

In this reaction, solid aluminum (Al) reacts with hydrochloric acid (HCl) to produce hydrogen gas (H₂) and aluminum chloride (AlCl₃). To understand the formation of the products, we first identify the charges of the ions involved. Aluminum, being in group 3A, has a charge of +3, while chlorine, from group 7A, has a charge of -1. When forming the ionic compound, the charges crisscross, resulting in aluminum chloride, which has the formula AlCl₃.

Next, we need to balance the chemical equation. Initially, we have one aluminum atom and three chlorine atoms on the product side. To balance the equation, we look for the lowest common multiple of the hydrogen atoms. The reactants yield three hydrogen atoms from HCl and two from H₂, leading us to a total of six hydrogen atoms. To achieve this, we place a coefficient of 6 in front of HCl, which gives us six chlorine and six hydrogen atoms. To balance the aluminum, we place a coefficient of 2 in front of Al on the reactant side, resulting in the balanced equation:

2 Al (s) + 6 HCl (aq) → 3 H₂ (g) + 2 AlCl₃ (aq).

This balanced equation illustrates the conservation of mass, where the number of atoms for each element is equal on both sides of the reaction.