Production of Hydrogen: Videos & Practice Problems

Hydrogen gas (H₂) can be produced through reactions involving ionic hydrides and metals with acids. Ionic hydrides react with water or acids, leading to a double displacement reaction that generates H₂ gas. Similarly, reactive metals oxidize when they react with acids like sulfuric or hydrochloric acid, also producing H₂. Balancing these reactions is crucial, ensuring the conservation of mass and charge, which is fundamental in stoichiometry and chemical equations.

From Ionic Hydrides

Hydrogen gas (H₂) can be produced through various chemical reactions, one of which involves ionic hydrides. Ionic hydrides, characterized by the presence of the hydride ion (H^-), react with water or acids due to their basic nature. This reaction can be illustrated using a metal hydride and an acid.

In this reaction, the ionic hydride can be represented as M²⁺ (where M is a metal) and the acid as H⁺. When these reactants are combined, a double displacement reaction occurs. The hydride ion (H^-) from the ionic hydride reacts with the hydrogen ion (H⁺) from the acid to form hydrogen gas (H₂). The remaining ions combine to form a new compound, MA₂, where A represents the anion from the acid.

To balance the reaction, it is essential to ensure that the number of hydrogen atoms on both sides is equal. Initially, there are three hydrogen atoms on the reactant side (two from the ionic hydride and one from the acid) and only two on the product side (from H₂). By placing a coefficient of 2 in front of H₂, the total number of hydrogen atoms on the product side becomes four. Consequently, a coefficient of 2 is also added in front of the compound MA₂ to maintain balance, resulting in a balanced equation that accurately represents the production of hydrogen gas from ionic hydrides and acids.

Production of Hydrogen Example

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)

From Metal and Acid

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.

Production of Hydrogen Example

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.

Complete and balance given reaction.
BaH₂(s) + H₂O(l) →

• A. BaH₂(s) + 2 H₂O(l) → 2 O₂(g) + BaH₄(aq)
• B. BaH₂(s) + 2 H₂O(l) → 2 H₂O₂(l) + Ba(s)
• C. 2 BaH₂(s) + 2 H₂O(l) → 2 Ba(OH)₂(aq)
• D. BaH₂(s) + 2 H₂O(l) → 2 H₂(g) + Ba(OH)₂(aq)

Answer: (D)

Complete and balance given reaction.
Zn(s) + H₂SO₄(aq) → 

• A. 2 Zn(s) + H₂SO₄(aq) → H₂(g) + Zn₂SO₄(aq)
• B. Zn(s) + H₂SO₄(aq) → H₂(g) + ZnSO₄(aq)
• C. Zn(s) + 2 H₂SO₄(aq) → 2 H₂(g) + Zn(SO₄)₂(aq)
• D. Zn(s) + 3 H₂SO₄(aq) → 3 H₂(g) + Zn(SO₄)₃(aq)

Answer: (B)

Here’s what students ask on this topic:

What are the main reactions that produce hydrogen gas?

Hydrogen gas (H₂) can be produced through several reactions. Two primary methods include the reaction of ionic hydrides with acids and the reaction of reactive metals with strong acids. In the first method, ionic hydrides react with acids in a double displacement reaction, forming H₂ gas and a salt. In the second method, reactive metals react with strong acids like sulfuric acid or hydrochloric acid, where the metal is oxidized, and H₂ gas is produced. Both reactions require balancing to ensure the number of atoms on both sides of the equation is equal.

How does the reaction between ionic hydrides and acids produce hydrogen gas?

In the reaction between ionic hydrides and acids, the hydride ion (H^-) from the ionic hydride reacts with the hydrogen ion (H⁺) from the acid to form hydrogen gas (H₂). The metal from the hydride forms a salt with the acid's anion. For example, if a metal hydride (MH) reacts with an acid (HA), the reaction can be represented as:

$M_2+H_2+A_2\to M_2{A}_2+H_2$

The reaction needs to be balanced to ensure the number of atoms on both sides of the equation is equal.

What is the role of reactive metals in the production of hydrogen gas?

Reactive metals play a crucial role in the production of hydrogen gas when they react with strong acids like sulfuric acid or hydrochloric acid. In this reaction, the metal is oxidized, meaning it loses electrons and becomes ionized. The hydrogen ions (H⁺) from the acid are reduced, forming hydrogen gas (H₂). For example, when a group 1A metal (M) reacts with an acid (HA), the reaction can be represented as:

$M+H_2\to M_{\mathrm{+}}+H_2$

The stoichiometry of the reaction must be adjusted to balance the hydrogen atoms on both sides of the equation.

How do you balance the chemical equation for the production of hydrogen gas from ionic hydrides and acids?

To balance the chemical equation for the production of hydrogen gas from ionic hydrides and acids, you need to ensure the number of atoms on both sides of the equation is equal. For example, consider the reaction between a metal hydride (MH) and an acid (HA):

$M_2+H_2+A_2\to M_2{A}_2+H_2$

First, break the reactants into their respective ions. Then, perform a double displacement reaction to form H₂ gas and a salt. Adjust the coefficients to balance the number of atoms on both sides. For instance, if you have 3 hydrogens on the reactant side and only 2 on the product side, you may need to place a coefficient of 2 in front of H₂ gas to balance the equation.

What is the significance of balancing chemical equations in the production of hydrogen gas?

Balancing chemical equations is crucial in the production of hydrogen gas because it ensures the conservation of mass and the correct stoichiometric proportions of reactants and products. An unbalanced equation can lead to incorrect predictions about the amounts of reactants needed and the quantities of products formed. For example, in the reaction between a metal hydride (MH) and an acid (HA) to produce hydrogen gas (H₂), balancing the equation ensures that the number of hydrogen atoms on both sides is equal, which is essential for accurate calculations and efficient chemical processes.