Problem 88 - Introductory Chemistry Atoms First

Question

In the chemical reaction for the "burning" of sugar, \(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}+6 \mathrm{O}_{2} \rightarrow 6 \mathrm{CO}_{2}+6 \mathrm{H}_{2} \mathrm{O}\), which substances are the reactants and which are the products? Does this equation represent a chemical change or a physical change?

Step-by-Step Solution

Answer

The reactants in the given chemical reaction are glucose (\(\mathrm{C_{6}H_{12}O_{6}}\)) and oxygen (\(\mathrm{O_{2}}\)), and the products are carbon dioxide (\(\mathrm{CO_{2}}\)) and water (\(\mathrm{H_{2}O}\)). This reaction represents a chemical change, as new substances with different chemical compositions are formed.

Step 1: Identify the reactants and products in the given chemical equation

The given chemical reaction is: \(\mathrm{C_{6}H_{12}O_{6}} + 6\;\mathrm{O_{2}} \rightarrow 6\;\mathrm{CO_{2}} + 6\;\mathrm{H_{2}O}\) In a chemical equation, the reactants are written on the left side of the arrow and the products appear on the right side of the arrow. In this case, the reactants are: - Glucose (\(\mathrm{C_{6}H_{12}O_{6}}\)) and - Oxygen (\(\mathrm{O_{2}}\)) The products are: - Carbon dioxide (\(\mathrm{CO_{2}}\)) and - Water (\(\mathrm{H_{2}O}\))

Step 2: Determine if the reaction represents a chemical change or a physical change

When a chemical reaction occurs, the atoms are rearranged to form new substances, and this process is called a chemical change. If there is only a change in the physical state without any change in the chemical composition, it is called a physical change. In the given reaction, glucose and oxygen are converted into carbon dioxide and water, which have different chemical compositions than the reactants. Therefore, this reaction represents a chemical change.

Key Concepts

Reactants and Products

In the context of a chemical reaction, understanding reactants and products is crucial. Imagine reactants as the ingredients you start with in a recipe. For the chemical reaction of glucose combustion, the reactants are glucose (\(\mathrm{C_{6}H_{12}O_{6}}\)) and oxygen (\(\mathrm{O_{2}}\)). These are the substances that undergo a transformation during the reaction.

• Reactants are always found on the left side of a chemical equation.
• They are the ingredients necessary to start the chemical change.

During the reaction, these reactants are converted into products, which are the final substances formed. For glucose combustion, the products are carbon dioxide (\(\mathrm{CO_{2}}\)) and water (\(\mathrm{H_{2}O}\)).

• Products are located on the right side of the arrow in a chemical equation.
• The formation of products signals that a new substance has been formed.

Chemical Change

A chemical change indicates a process where substances transform into chemically different substances. When glucose combusts, it undergoes such a change; this is more than just a matter of shifting states like solid to liquid.

• Chemical changes involve rearrangement of atoms.
• Original compounds are no longer present, forming entirely new substances.

In the case of glucose combustion, both glucose and oxygen cease to exist in their original forms.
The reaction results in the production of carbon dioxide and water, showcasing clear evidence of a chemical change:

• New chemical bonds form while others break apart.
• The chemical properties and composition of the products differ from the reactants.

This transformation can often release energy, as substances with different internal energies form a new configuration.

Glucose Combustion

Glucose combustion is a specific type of chemical reaction where glucose reacts with oxygen. This reaction is important as it releases energy that is essential for various biological and mechanical processes.

• The equation for glucose combustion is: \(\mathrm{C_{6}H_{12}O_{6}} + 6\;\mathrm{O_{2}} \rightarrow 6\;\mathrm{CO_{2}} + 6\;\mathrm{H_{2}O}\).
• Each molecule of glucose combines with six molecules of oxygen, showing the stoichiometry or balance of the equation.

This specific reaction is a classic example of oxidation, where oxygen is a critical reactant.
The process is part of cellular respiration in living organisms, showcasing its importance both chemically and biologically.

• It is an exothermic reaction, meaning it releases heat.
• Breaking down glucose in this manner provides energy for cellular functions in organisms.

Hence, glucose combustion not only illustrates a chemical change but also highlights the utilitarian aspect of chemical reactions in everyday life.