Question

For each of the following unbalanced chemical equations, write the corresponding chemical statement. (a) \(\mathrm{K}+\mathrm{H}_{2} \mathrm{O} \longrightarrow \mathrm{KOH}+\mathrm{H}_{2}\) (b) \(\mathrm{Ba}(\mathrm{OH})_{2}+\mathrm{HCl} \longrightarrow \mathrm{BaCl}_{2}+\mathrm{H}_{2} \mathrm{O}\) (c) \(\mathrm{Cu}+\mathrm{HNO}_{3} \longrightarrow \mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2}+\mathrm{NO}+\mathrm{H}_{2} \mathrm{O}\) (d) \(\mathrm{Al}+\mathrm{H}_{2} \mathrm{SO}_{4} \longrightarrow \mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}+\mathrm{H}_{2}\) (e) \(\mathrm{HI} \longrightarrow \mathrm{H}_{2}+\mathrm{I}\)

Short answer

Write chemical statements by translating equations into words.

Step-by-step solution

Understand the Task

The task is to write a chemical statement for each given unbalanced chemical equation. A chemical statement describes the reaction that the equation represents, interpreting the equation into words.

Equation (a) Statement

For the equation \( \mathrm{K} + \mathrm{H}_2 \mathrm{O} \longrightarrow \mathrm{KOH} + \mathrm{H}_2 \): Solid potassium (K) reacts with water (H₂O) to form potassium hydroxide (KOH) and hydrogen gas (H₂).

Equation (b) Statement

For the equation \( \mathrm{Ba(OH)}_2 + \mathrm{HCl} \longrightarrow \mathrm{BaCl}_2 + \mathrm{H}_2 \mathrm{O} \): Barium hydroxide (Ba(OH)₂) reacts with hydrochloric acid (HCl) to produce barium chloride (BaCl₂) and water (H₂O).

Equation (c) Statement

For the equation \( \mathrm{Cu} + \mathrm{HNO}_3 \longrightarrow \mathrm{Cu(NO}_3)_2 + \mathrm{NO} + \mathrm{H}_2 \mathrm{O} \): Copper (Cu) reacts with nitric acid (HNO₃) to yield copper(II) nitrate (Cu(NO₃)₂), nitrogen monoxide (NO), and water (H₂O).

Equation (d) Statement

For the equation \( \mathrm{Al} + \mathrm{H}_2 \mathrm{SO}_4 \longrightarrow \mathrm{Al}_2(\mathrm{SO}_4)_3 + \mathrm{H}_2 \): Aluminum (Al) reacts with sulfuric acid (H₂SO₄) to form aluminum sulfate (Al₂(SO₄)₃) and hydrogen gas (H₂).

Equation (e) Statement

For the equation \( \mathrm{HI} \longrightarrow \mathrm{H}_2 + \mathrm{I} \): Hydrogen iodide (HI) decomposes to form hydrogen gas (H₂) and iodine (I).

Key concepts

Chemical Reaction

A chemical reaction occurs when substances, known as reactants, are transformed into new substances, called products. During a reaction, chemical bonds within the reactants are broken and formed anew in the products. This leads to the creation of substances with different chemical compositions and properties than the original reactants. Chemical reactions are fundamental to both chemistry and biology because they are how matter is transformed.

To identify a chemical reaction, look for changes such as:

• Formation of a gas (bubbles)
• Change in color
• Temperature change
• Formation of a precipitate

These observable changes indicate that a reaction has occurred. For example, when mixing potassium (K) with water (H₂O), you get potassium hydroxide (KOH) and hydrogen gas (H₂), illustrating a classic chemical reaction.

Balancing Equations

Balancing equations is a critical skill in chemistry. It ensures that the principle of conservation of mass is honored. This principle states that matter cannot be created or destroyed in an isolated system. Thus, in a chemical reaction, the number of each type of atom must be the same on both sides of the equation.

The general process of balancing equations involves:

• Counting the number of atoms of each element on both sides
• Using coefficients to adjust the number of atoms to be equal on both sides
• Re-checking the equation to ensure balance

For example, with the reaction between aluminum (Al) and sulfuric acid (H₂SO₄), the equation needs balancing to ensure the number of Al, S, H, and O atoms are equal on both sides.
Balanced equation: \[ 2 ext{Al} + 3 ext{H}_2 ext{SO}_4 ightarrow ext{Al}_2( ext{SO}_4)_3 + 3 ext{H}_2 \] Balancing empowers chemists to predict the amounts of products generated in a chemical reaction.

Chemical Statements

Chemical statements verbally describe what happens in a chemical equation. They translate symbols and formulas into readable descriptions, helping one to understand the nature and outcome of the reaction.

For example, consider the equation for copper reacting with nitric acid: \[ ext{Cu} + ext{HNO}_3 ightarrow ext{Cu(NO}_3)_2 + ext{NO} + ext{H}_2 ext{O} \] In words, this means: Copper reacts with nitric acid to yield copper(II) nitrate, nitrogen monoxide, and water.
This translation is vital because it enables those not familiar with chemical symbols to grasp what is happening in the reaction. Chemical statements clarify the substances involved, the nature of the reaction, and the products formed.

Reagents and Products

In any chemical reaction, the reagents, also called reactants, are the starting materials used in the process. The products are the new substances formed as a result of the reaction. Understanding reagents and products is essential to predicting how different chemicals will interact.

For instance, in the unbalanced equation \[ ext{Ba(OH)}_2 + ext{HCl} ightarrow ext{BaCl}_2 + ext{H}_2 ext{O} \] we identify:

• Reagents: Barium hydroxide (Ba(OH)₂), Hydrochloric acid (HCl)
• Products: Barium chloride (BaCl₂), Water (H₂O)

In ingesting these concepts, students can predict both the reactants needed and the type of products formed. The reaction between these chemicals elucidates how acid-base reactions work and their visible outcomes.