Problem 105 - Chemistry Matter and Change

Question

Write the word equation for each of these skeleton equations. \(\mathrm{C}_{6} \mathrm{H}_{6}\) is the formula for benzene. a. \(C_{6} \mathrm{H}_{6}(1)+\mathrm{O}_{2}(\mathrm{g}) \rightarrow \mathrm{CO}_{2}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(1)\) b. \(\mathrm{CO}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{g}) \rightarrow \mathrm{CO}_{2}(\mathrm{g})\) c. \(\mathrm{Cl}_{2}(\mathrm{g})+\mathrm{NaBr}(\mathrm{s}) \rightarrow \mathrm{NaCl}(\mathrm{s})+\mathrm{Br}_{2}(\mathrm{g})\) d. \(\mathrm{CaCO}_{3}(\mathrm{s}) \rightarrow \mathrm{CaO}(\mathrm{s})+\mathrm{CO}_{2}(\mathrm{g})\)

Step-by-Step Solution

Answer

a. Benzene (liquid) + Oxygen (gas) → Carbon dioxide (gas) + Water (liquid) b. Carbon monoxide (gas) + Oxygen (gas) → Carbon dioxide (gas) c. Chlorine (gas) + Sodium bromide (solid) → Sodium chloride (solid) + Bromine (gas) d. Calcium carbonate (solid) → Calcium oxide (solid) + Carbon dioxide (gas)

Step 1: Identify the reactants and products

In this reaction, the reactants are \(C_{6}H_{6}(l)\), which is benzene, and \(O_{2}(g)\), which is oxygen. The products are \(CO_{2}(g)\), which is carbon dioxide, and \(H_{2}O(l)\), which is water.

Step 2: Write the word equation

The word equation for this reaction can be written as: Benzene (liquid) + Oxygen (gas) → Carbon dioxide (gas) + Water (liquid) b. \(CO(g)+O_{2}(g) \rightarrow CO_{2}(g)\)

Step 1: Identify the reactants and products

In this reaction, the reactants are \(CO(g)\), which is carbon monoxide, and \(O_{2}(g)\), which is oxygen. The product is \(CO_{2}(g)\), which is carbon dioxide.

Step 2: Write the word equation

The word equation for this reaction can be written as: Carbon monoxide (gas) + Oxygen (gas) → Carbon dioxide (gas) c. \(Cl_{2}(g)+NaBr(s) \rightarrow NaCl(s)+Br_{2}(g)\)

Step 1: Identify the reactants and products

In this reaction, the reactants are \(Cl_{2}(g)\), which is chlorine, and \(NaBr(s)\), which is sodium bromide. The products are \(NaCl(s)\), which is sodium chloride, and \(Br_{2}(g)\), which is bromine.

Step 2: Write the word equation

The word equation for this reaction can be written as: Chlorine (gas) + Sodium bromide (solid) → Sodium chloride (solid) + Bromine (gas) d. \(CaCO_{3}(s) \rightarrow CaO(s)+CO_{2}(g)\)

Step 1: Identify the reactants and products

In this reaction, the reactant is \(CaCO_{3}(s)\), which is calcium carbonate. The products are \(CaO(s)\), which is calcium oxide, and \(CO_{2}(g)\), which is carbon dioxide.

Step 2: Write the word equation

The word equation for this reaction can be written as: Calcium carbonate (solid) → Calcium oxide (solid) + Carbon dioxide (gas)

Key Concepts

Word Equations

Word equations are a simple way to describe a chemical reaction using words instead of symbols or formulas. In a word equation, you write out the names of the reactants and products as they appear and separate them with an arrow to show the direction of the reaction.
For example, in the reaction with benzene and oxygen forming carbon dioxide and water, the word equation would be **Benzene (liquid) + Oxygen (gas) → Carbon dioxide (gas) + Water (liquid)**.
This type of equation is useful for understanding the basic components of a reaction without knowing the chemical formulas. It helps students visualize the chemical changes occurring.

Skeleton Equations

Skeleton equations are a shorthand way to depict a chemical reaction using chemical formulas rather than words, but without specifying the amounts of reactants and products involved. These equations include the chemical symbols for all the substances involved and show their physical states, like solid (s), liquid (l), gas (g), or aqueous (aq).
For instance, the skeleton equation for the reaction of benzene with oxygen is written as:

• \(C_6H_6(l) + O_2(g) \rightarrow CO_2(g) + H_2O(l)\)

This form is more compact and easier to balance but does not immediately convey information about quantities or proportions. It's a critical intermediate step before balancing the chemical equation.

Reactants and Products

In any chemical reaction, the starting materials are known as reactants, while the substances formed as a result of the reaction are called products. Understanding this basic concept is essential to mastering chemical equations.
For example, in the reaction involving carbon monoxide and oxygen to form carbon dioxide, the reactants are:

• Carbon monoxide (gas), \(CO(g)\)
• Oxygen (gas), \(O_2(g)\)

The product of this reaction is carbon dioxide (gas), \(CO_2(g)\).
Recognizing which substances are reactants and which are products helps in balancing equations and understanding the direction of the chemical reaction.

Combustion Reactions

Combustion reactions are a type of chemical reaction where a substance combines with oxygen to release energy, usually in the form of heat and light. These reactions often involve hydrocarbons like benzene, which burn to form carbon dioxide and water.
A typical example of combustion is the burning of benzene:

• **Benzene (liquid) + Oxygen (gas) → Carbon dioxide (gas) + Water (liquid)**

This reaction releases energy, making it an exothermic process. Combustion reactions are crucial in everyday life as they are the basis for energy production in engines and power plants, and understanding them is key to studying energy transfer and environmental effects.