Question

Write balanced equations for the following reactions: (a) sulfur dioxide with water, (b) lithium oxide in water, \((\mathbf{c})\) zinc oxide with dilute hydrochloric acid, (d) arsenic trioxide with aqueous potassium hydroxide.

Short answer

(a) SO2 + H2O → H2SO3 (b) Li2O + H2O → 2LiOH (c) ZnO + 2HCl → ZnCl2 + H2O (d) As2O3 + 3KOH → 2K3AsO3 + 3H2O

Step-by-step solution

(a) Sulfur dioxide with water

The reactants are sulfur dioxide (SO2) and water (H2O), and the product of this reaction is sulfurous acid (H2SO3). Write the unbalanced equation: SO2 + H2O → H2SO3 Now balance the equation: There is already an equal number of atoms on both sides, so the equation is balanced. The final balanced equation for the reaction between sulfur dioxide and water is: SO2 + H2O → H2SO3

(b) Lithium oxide in water

The reactants are lithium oxide (Li2O) and water (H2O), and the product of this reaction is lithium hydroxide (LiOH). Write the unbalanced equation: Li2O + H2O → LiOH Now balance the equation: To balance the lithium atoms, place the coefficient of 2 in front of LiOH: Li2O + H2O → 2LiOH The final balanced equation for the reaction between lithium oxide in water is: Li2O + H2O → 2LiOH

(c) Zinc oxide with dilute hydrochloric acid

The reactants are zinc oxide (ZnO) and hydrochloric acid (HCl), and the products of this reaction are zinc chloride (ZnCl2) and water (H2O). Write the unbalanced equation: ZnO + HCl → ZnCl2 + H2O Now balance the equation: To balance the chlorine atoms, place the coefficient of 2 in front of HCl: ZnO + 2HCl → ZnCl2 + H2O The final balanced equation for the reaction between zinc oxide and dilute hydrochloric acid is: ZnO + 2HCl → ZnCl2 + H2O

(d) Arsenic trioxide with aqueous potassium hydroxide

The reactants are arsenic trioxide (As2O3) and potassium hydroxide (KOH), and the products of this reaction are potassium arsenite (K3AsO3) and water (H2O). Write the unbalanced equation: As2O3 + KOH → K3AsO3 + H2O Now balance the equation: Since there are 2 arsenic atoms and 3 potassium atoms in the products, place the coefficients of 2 in front of K3AsO3 and 3 in front of KOH, respectively: As2O3 + 3KOH → 2K3AsO3 + H2O To balance the hydrogen atoms, place the coefficient of 3 in front of H2O: As2O3 + 3KOH → 2K3AsO3 + 3H2O The final balanced equation for the reaction between arsenic trioxide and aqueous potassium hydroxide is: As2O3 + 3KOH → 2K3AsO3 + 3H2O

Key concepts

Balancing Chemical Equations

Balancing chemical equations is a fundamental skill in chemistry. It ensures that the law of conservation of mass is adhered to, which states that matter cannot be created or destroyed in a chemical reaction. When we balance equations, we ensure that the number of atoms for each element is the same on both sides of the equation.

Balancing begins by writing the unbalanced equation using chemical formulas for reactants and products. This gives a visual representation of the process. Then, adjust coefficients, which are whole numbers placed in front of chemical formulas, to balance the atoms on each side. Always start with the most complex molecule and leave the simplest for last, often balancing hydrogen and oxygen atoms last, as they are frequently found in multiple compounds within reactions.

For example, when balancing the reaction of zinc oxide with dilute hydrochloric acid:

• Start with the unbalanced equation: \(\text{ZnO + HCl} \rightarrow \text{ZnCl}_2 + \text{H}_2\text{O}\)
• Balance chlorine by placing a 2 before \(\text{HCl}\): \(\text{ZnO + 2HCl} \rightarrow \text{ZnCl}_2 + \text{H}_2\text{O}\)

The reaction is now balanced.

Inorganic Chemistry

Inorganic chemistry is a branch of chemistry that studies the properties and behavior of inorganic compounds, which are compounds not covered by organic chemistry. These often include salts, metals, and minerals that do not contain carbon-hydrogen bonds.

One of the primary focuses of inorganic chemistry is understanding and predicting the behavior of these substances during chemical reactions. Understanding their reactivity helps explain natural processes and industrial applications, such as material fabrication and environmental impacts.

Chemical reactions like those between sulfur dioxide and water, or arsenic trioxide and potassium hydroxide, are typical examples in inorganic chemistry. These reactions often involve:

• Formation of acid or base compounds, such as the conversion of \(\text{SO}_2 + \text{H}_2\text{O} \rightarrow \text{H}_2\text{SO}_3\), forming sulfurous acid.
• Neutralization reactions, as seen with zinc oxide and hydrochloric acid forming zinc chloride and water, demonstrating typical inorganic processes.

Chemical Equation Representation

Chemical equation representation is crucial for understanding chemical reactions. A chemical equation uses symbols and formulas to represent the reactants and products in a reaction. It provides a concise way to express what substances are involved and in what proportions.

The equation's format typically involves showing the reactants on the left, an arrow indicating the direction of the reaction, and the products on the right, like this: \(\text{Reactants} \rightarrow \text{Products}\). This notation helps chemists easily understand and predict the outcomes of reactions, calculate reactant quantities needed, and identify potential by-products.

For instance, in representing the reaction of lithium oxide in water, the chemical equation:

• \(\text{Li}_2\text{O} + \text{H}_2\text{O} \rightarrow 2\text{LiOH}\)

Here, the symbols show two lithium hydroxide molecules produced for each lithium oxide and water molecule reacting. Properly representing these reactions allows chemists to efficiently study and apply these chemical processes.