Problem 105 - Chemistry Matter and Change

Question

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

Step-by-Step Solution

Answer

a. benzene + oxygen gas → carbon dioxide + water b. carbon monoxide + oxygen gas → carbon dioxide c. chlorine gas + sodium bromide → sodium chloride + bromine gas d. calcium carbonate → calcium oxide + carbon dioxide

Step 1: Identify Reactants and Products (Part a)

In the equation \(C_6H_6(l) + O_2(g) \rightarrow CO_2(g) + H_2O(l)\), the reactants are benzene \((C_6H_6)\) and oxygen gas \((O_2)\), and the products are carbon dioxide \((CO_2)\) and water \((H_2O)\).

Step 2: Write the Word Equation (Part a)

Convert the chemical equation from Step 1 into a word equation: *benzene + oxygen gas \(\rightarrow\) carbon dioxide + water*.

Step 3: Identify Reactants and Products (Part b)

In the equation \(CO(g) + O_2(g) \rightarrow CO_2(g)\), the reactants are carbon monoxide \((CO)\) and oxygen gas \((O_2)\), and the product is carbon dioxide \((CO_2)\).

Step 4: Write the Word Equation (Part b)

Convert the chemical equation from Step 3 into a word equation: *carbon monoxide + oxygen gas \(\rightarrow\) carbon dioxide*.

Step 5: Identify Reactants and Products (Part c)

In the equation \(Cl_2(g) + NaBr(s) \rightarrow NaCl(s) + Br_2(g)\), the reactants are chlorine gas \((Cl_2)\) and sodium bromide \((NaBr)\), and the products are sodium chloride \((NaCl)\) and bromine gas \((Br_2)\).

Step 6: Write the Word Equation (Part c)

Convert the chemical equation from Step 5 into a word equation: *chlorine gas + sodium bromide \(\rightarrow\) sodium chloride + bromine gas*.

Step 7: Identify Reactants and Products (Part d)

In the equation \(CaCO_3(s) \rightarrow CaO(s) + CO_2(g)\), the reactant is calcium carbonate \((CaCO_3)\), and the products are calcium oxide \((CaO)\) and carbon dioxide \((CO_2)\).

Step 8: Write the Word Equation (Part d)

Convert the chemical equation from Step 7 into a word equation: *calcium carbonate \(\rightarrow\) calcium oxide + carbon dioxide*.

Key Concepts

Chemical Reactions

Chemical reactions are the processes in which substances, known as reactants, transform into new substances, called products. During a chemical reaction, the bonds between atoms are broken, and new bonds are formed, resulting in a change of composition of the substances involved.

Chemical reactions can be observed in everyday life, such as when food is cooked, iron rusts, or when gasoline is burned in a car engine. These reactions are usually classified into different types:

• Combustion: a substance combines with oxygen, releasing energy (e.g., burning wood).
• Decomposition: a compound breaks down into simpler substances (e.g., electrolysis of water).
• Single displacement: one element replaces another in a compound (e.g., zinc metal displacing copper in a solution).

Understanding chemical reactions involves identifying the reactants and predicting the products formed based on their chemical properties.

Reactants and Products

In a chemical equation, reactants are the starting substances, while products are the substances formed as a result of the reaction. For any chemical reaction, it is essential to identify which are the reactants and which are the products.

For example, consider the chemical equation for the combustion of benzene:

• Reactants: **Benzene** \(C_6H_6 \) and **Oxygen gas** \(O_2\)
• Products: **Carbon dioxide** \(CO_2\) and **Water** \(H_2O\)

Identifying reactants and products helps in understanding the flow of the reaction and allows for the prediction of the outcome. Typically, reactants are written on the left side of a chemical equation, while products are shown on the right side. The arrow indicates the direction of the chemical reaction.

Chemical Equations

Chemical equations provide a concise way of representing chemical reactions. They show which reactants are involved and what products are formed, along with their respective states, such as solid \((s)\), liquid \((l)\), gas \((g)\), or aqueous \((aq)\) solutions.

Writing a chemical equation involves:

• Representing each substance with its chemical formula.
• Balancing the equation to adhere to the law of conservation of mass, ensuring the same number of each type of atom on both sides of the equation.

For instance, consider the combustion of carbon monoxide with oxygen:

• Unbalanced Equation: \(CO(g) + O_2(g) \rightarrow CO_2(g)\)
• Balanced Equation: \(2CO(g) + O_2(g) \rightarrow 2CO_2(g)\)

Balancing chemical equations ensures that the number of atoms for each element is the same on both sides of the equation, maintaining the principle of mass conservation in every chemical reaction.