Question

Ethane burns in alr to form carbon dixode and water vapor. MISSED THIS? Read Section 10.10 ; Watch ME 10.11 $$ 2 \mathrm{H}_{3} \mathrm{C}-\mathrm{CH}_{3}(\mathrm{x})+7 \mathrm{O}_{2}(\mathrm{~s}) \longrightarrow 4 \mathrm{CO}_{2}(g)+6 \mathrm{H}_{2} \mathrm{O}(\mathrm{s}) $$

Short answer

Balanced reaction: 2 C2H6(g) + 7 O2(g) \rightarrow 4 CO2(g) + 6 H2O(g), with corrected states of matter.

Step-by-step solution

Understand the Chemical Equation

Analyze the given chemical equation, which represents the combustion of ethane (H3C-CH3) in the presence of oxygen (O2) to form carbon dioxide (CO2) and water (H2O). Note that '(s)', '(x)', and '(g)' refer to the physical states of the substances involved: solid, mixture, and gas, respectively.

Balancing the Equation

Check that the chemical equation is balanced. In this case, the coefficients indicate that the reactants and products are balanced. There are 2 ethane molecules, 7 diatomic oxygen molecules, 4 carbon dioxide molecules, and 6 water molecules. This satisfies the law of conservation of mass.

Writing the States of Matter

Correct the states of matter based on typical conditions for a combustion reaction. Ethane and oxygen are gases at room temperature and during combustion (change from '(x)' and '(s)' to '(g)'). Water in a combustion reaction is typically in the vapor state, indicating a gaseous form as well (change from '(s)' to '(g)').

Key concepts

Chemical Equations

Chemical equations are vital in understanding the process and outcomes of a chemical reaction. They serve as a recipe that demonstrates how different chemicals, known as reactants, interact to form new substances, known as products. Just like a cooking recipe shows the ingredients and the final dish, a chemical equation shows all the participants in a reaction and the end result. In the case of ethane's combustion, the reactants are ethane \(C_2H_6\) and oxygen \(O_2\), while the products are carbon dioxide \(CO_2\) and water \(H_2O\).

It's crucial to represent each substance with its correct chemical formula, ensuring that the atoms of each element are accounted for. In educational settings, it can help to visualize the molecules involved in the reaction. For example, ethane, with its two carbon atoms and six hydrogen atoms, reacts with oxygen to form new molecules that are completely different in terms of their physical and chemical properties.

Balancing Chemical Equations

Balancing chemical equations is like solving a puzzle where you ensure that the number of atoms for each element is the same on both sides of the equation. This reflects the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction.

To achieve a balanced equation, we adjust coefficients—the numbers placed before chemical formulas—to ensure that there are equal numbers of each type of atom on both the reactant and product sides of the equation. In our combustion example, the balanced equation shows that two molecules of ethane react with seven molecules of diatomic oxygen to produce four molecules of carbon dioxide and six molecules of water vapor. Balancing equations ensures that we comply with scientific laws and provides a clear understanding of the stoichiometry— or quantitative relationship—between reactants and products in a chemical reaction.

States of Matter

States of matter indicate the physical form that different chemicals can take: solids, liquids, gases, and, though not present in our example, plasma. In chemical reactions, it's important to note the state of matter for each reactant and product because these states can affect how substances interact and the conditions under which the reaction occurs.

Different states have different properties: solids have a fixed shape and volume, liquids have a fixed volume but adapt to the shape of their container, and gases completely fill any container they're in. In the provided chemical equation for ethane's combustion, the states of matter were initially labelled incorrectly. After adjusting, we should note that both ethane and oxygen are gases (\(g\)) at room temperature, and so is water when produced in a combustion reaction, hence water vapor (\(g\)).

Law of Conservation of Mass

The law of conservation of mass is a fundamental principle in chemistry, stating that the total mass of reactants in a chemical reaction is equal to the total mass of the products. This principle is the basis for balancing chemical equations because it implies that atoms are neither created nor destroyed during a chemical reaction, only rearranged.

In the context of the combustion of ethane, we can use this law to check our work when balancing the chemical equation. By ensuring that there are the same numbers of each type of atom on both sides of the equation, we honor the law of conservation of mass. Remember that the mass before the reaction (ethane and oxygen molecules) will be exactly the same as the mass after the reaction has occurred (carbon dioxide and water molecules), regardless of any changes in the state of matter or energy released.