Balancing another combustion reaction | Chemical reactions | High school chemistry | Khan Academy

Khan Academy
19 Nov 201404:57
EducationalLearning
32 Likes 10 Comments

TLDRThe script discusses the process of balancing a chemical equation for the combustion reaction of ethane (C2H6) with molecular oxygen, resulting in carbon dioxide and water. It emphasizes the importance of balancing elements one by one, starting with hydrogen and carbon, and adjusting the oxygen last. The video demonstrates the step-by-step method of achieving a balanced equation with whole number coefficients, highlighting the need to adjust coefficients to ensure all elements are balanced on both sides of the equation.

Takeaways
  • 🔍 The script discusses a combustion reaction involving ethane (C2H6) and oxygen, resulting in carbon dioxide and water.
  • 🔄 The initial chemical equation provided is unbalanced, with an unequal number of carbon, hydrogen, and oxygen atoms on each side.
  • 📝 To balance the equation, the script suggests starting with elements in complex molecules and saving the simpler molecules for last adjustment.
  • 💧 Hydrogen is balanced first by multiplying the water molecules by three, resulting in six hydrogen atoms on both sides of the equation.
  • 🌐 Carbon is then balanced by changing the number of carbon dioxide molecules to two, aligning the carbon atoms on both sides.
  • 🔄 The script highlights the process of balancing oxygen, which involves adjusting the number of oxygen molecules to match the total oxygen atoms on both sides.
  • 🧪 The concept of using whole numbers for coefficients in chemical equations is emphasized, avoiding fractions like 'three-and-a-half'.
  • ✅ The final step involves multiplying all coefficients by two to ensure that all elements have whole number coefficients, resulting in a balanced equation.
  • 📚 The script serves as an educational guide on how to balance chemical equations, particularly for combustion reactions.
  • 📈 The process demonstrates the importance of systematic adjustments to coefficients to achieve balance in chemical reactions.
  • 📝 The final balanced equation is re-written, showing ethane and oxygen as reactants and carbon dioxide and water as products, all with whole number coefficients.
Q & A

  • What is the main topic of the video script?

    -The main topic of the video script is the process of balancing a chemical equation for the combustion reaction of ethane (C2H6) with molecular oxygen.

  • What is ethane and how many carbon and hydrogen atoms does it contain?

    -Ethane is a hydrocarbon with the chemical formula C2H6, which means each molecule of ethane contains two carbon atoms and six hydrogen atoms.

  • What is the initial state of the chemical equation presented in the script?

    -The initial state of the chemical equation is unbalanced, with an unequal number of carbon, hydrogen, and oxygen atoms on each side of the equation.

  • Why does the script suggest balancing the hydrogen atoms first?

    -The script suggests balancing the hydrogen atoms first because it simplifies the process by allowing the instructor to adjust the number of water molecules, which in turn affects the oxygen atoms without altering the carbon atoms.

  • What is the strategy for balancing the carbon atoms in the equation?

    -The strategy for balancing the carbon atoms involves adjusting the number of carbon dioxide molecules on the right side of the equation to match the number of carbon atoms in the ethane on the left side.

  • How does the instructor plan to balance the oxygen atoms in the equation?

    -The instructor plans to balance the oxygen atoms by adjusting the number of dioxygen molecules on the left side of the equation after the carbon and hydrogen atoms have been balanced.

  • What is the final step the instructor takes to ensure whole number coefficients in the balanced equation?

    -The final step is to multiply all coefficients by two, which converts the fractional coefficient (3.5) into a whole number (7) and ensures that all coefficients are whole numbers.

  • Why is it important to have whole number coefficients in a chemical equation?

    -Whole number coefficients are important because they represent the stoichiometric amounts of reactants and products in a balanced chemical reaction, making the equation more standard and easier to interpret.

  • What does the term 'stoichiometric amounts' refer to in the context of chemical equations?

    -Stoichiometric amounts refer to the proportions in which reactants and products are involved in a chemical reaction, ensuring that the number of atoms of each element is conserved according to the law of conservation of mass.

  • How does the script demonstrate the process of balancing a chemical equation?

    -The script demonstrates the process by sequentially balancing the atoms of hydrogen, carbon, and then oxygen, adjusting coefficients to achieve equality on both sides of the equation, and ensuring that all coefficients are whole numbers.

  • What is the significance of the law of conservation of mass in balancing chemical equations?

    -The law of conservation of mass states that matter cannot be created or destroyed in a chemical reaction. This principle is fundamental in balancing chemical equations, ensuring that the number of atoms of each element is the same on both sides of the equation.

Outlines
00:00
🔥 Ethane Combustion Reaction Overview

This paragraph introduces the combustion reaction of ethane (C2H6), a molecule with two carbons and six hydrogens, as it reacts with molecular oxygen. The initial chemical equation is presented as unbalanced, with a discrepancy in the number of carbon, hydrogen, and oxygen atoms on each side. The paragraph outlines a strategy for balancing the equation by adjusting the coefficients of the molecules involved, starting with the carbon and hydrogen atoms and saving the oxygen for last due to its simpler adjustment process.

🔄 Balancing the Hydrogen in Ethane Combustion

The speaker begins the balancing process by addressing the hydrogen atoms first. With six hydrogens on the left side of the equation, the speaker multiplies the water molecules on the right side by three to achieve six hydrogen atoms, resulting in three water molecules each containing two hydrogen atoms. This step ensures that the hydrogen atoms are balanced across the reaction equation.

🌐 Balancing Carbon and Preparing to Address Oxygen

After balancing the hydrogen atoms, the focus shifts to the carbon atoms. The speaker notes that there are two carbons on the left side and only one molecule of carbon dioxide on the right, which is then doubled to create two molecules of carbon dioxide, effectively balancing the carbon atoms. The speaker then prepares to address the oxygen atoms, which will involve adjusting the dioxygen molecule on the left side of the equation.

⚖️ Achieving Oxygen Balance Through Adjustments

The paragraph details the process of balancing the oxygen atoms. Initially, there are seven oxygen atoms on the right side (four from the two carbon dioxide molecules and three from the three water molecules) compared to only two on the left side. To balance this, the speaker multiplies the dioxygen molecule by 3.5, resulting in 7 oxygen atoms on both sides. However, to maintain whole number coefficients, the entire equation is then multiplied by two, yielding a balanced chemical equation with whole number coefficients for all reactants and products.

Mindmap
Keywords
💡Combustion Reaction
A combustion reaction is a chemical process where a substance reacts rapidly with oxygen, typically producing heat and light. In the context of the video, the combustion of ethane with molecular oxygen is the primary example, illustrating the process of balancing a chemical equation in a combustion scenario.
💡Ethane (C2H6)
Ethane is an organic compound with the molecular formula C2H6, consisting of two carbon atoms and six hydrogen atoms. It is a colorless, odorless gas that is a major component of natural gas. In the video, ethane is the reactant undergoing combustion, and its molecular structure is crucial for understanding the chemical equation.
💡Molecular Oxygen
Molecular oxygen, with the chemical formula O2, is the form of oxygen that is most commonly found in the Earth's atmosphere. It is a diatomic molecule, meaning it consists of two oxygen atoms bonded together. In the script, molecular oxygen is the oxidizing agent in the combustion reaction with ethane.
💡Carbon Dioxide (CO2)
Carbon dioxide is a chemical compound with the formula CO2. It is a colorless, odorless gas that is produced during the combustion of carbon-containing compounds. In the video, it is one of the products of the combustion reaction of ethane, indicating the formation of this gas during the process.
💡Water (H2O)
Water is a molecule consisting of two hydrogen atoms and one oxygen atom, with the chemical formula H2O. It is a liquid at room temperature and is the other product of the combustion reaction shown in the video, demonstrating the formation of liquid water from the reaction of ethane with oxygen.
💡Balancing Chemical Equations
Balancing chemical equations is the process of ensuring that the number of atoms of each element on the reactant side of an equation is equal to the number on the product side. This principle is fundamental to the conservation of mass. The video script focuses on this process, showing step-by-step how to balance the equation for the combustion of ethane.
💡Elemental Balance
Elemental balance refers to the equality of the number of atoms of each element in a chemical reaction. The script emphasizes the importance of elemental balance by pointing out the initial imbalance in the carbon, hydrogen, and oxygen atoms and then correcting it to achieve a balanced equation.
💡Coefficients
In chemistry, coefficients are numerical values placed in front of chemical formulas to indicate the number of molecules or atoms participating in a reaction. The script discusses adjusting coefficients to balance the chemical equation, such as multiplying by two to achieve whole numbers.
💡Mauve Color
While not a scientific term, the use of 'mauve color' in the script serves as a visual aid to distinguish and highlight different parts of the chemical equation during the explanation. It helps viewers to follow along with the changes being made to balance the equation.
💡Whole Number Coefficients
Whole number coefficients are preferred in chemical equations because they represent the simplest whole number ratio between molecules in a balanced equation. The script concludes with the adjustment of coefficients to ensure they are all whole numbers, which is a standard practice in chemistry.
💡Algebraic Equations
Although not the main focus, the script makes a brief comparison to algebraic equations when discussing the multiplication of coefficients. This serves to draw a parallel between the balancing of chemical equations and solving algebraic equations, which involves similar principles of maintaining equality.
Highlights

Introduction of a new combustion reaction involving ethane (C2H6) and molecular oxygen.

Ethane has two carbons and six hydrogen atoms in each molecule, reacting with oxygen to form carbon dioxide and water.

The initial chemical equation is unbalanced, with an unequal number of carbon, hydrogen, and oxygen atoms on each side.

A strategy for balancing chemical equations is discussed, focusing on elements in standalone molecules last.

Balancing of hydrogen atoms by adjusting the number of water molecules to match the number of hydrogens in ethane.

Adjustment of carbon dioxide molecules to balance the carbon atoms in the reaction.

A method to balance oxygen atoms by manipulating the number of dioxygen molecules.

Explanation of how changes in one part of the equation affect the balance of oxygen atoms.

The concept of using whole numbers for coefficients in balanced chemical equations is emphasized.

Multiplication of all coefficients by two to achieve whole numbers and a fully balanced equation.

Final balanced chemical equation for the combustion of ethane presented.

The importance of balancing all elements in a chemical reaction for it to be considered correct.

Demonstration of the step-by-step process to balance a complex chemical equation.

Highlighting the flexibility in choosing which element to balance first in complex molecules.

The use of color coding to distinguish between different steps in the balancing process.

Clarification on the mathematical approach to balance oxygen atoms by using fractions and then converting to whole numbers.

Emphasis on the standard practice of using whole number coefficients in chemical equations.

A recap of the entire process to ensure the chemical equation is balanced with whole numbers.

Transcripts

Browse More Related Video

Introduction to Balancing Chemical Equations

How To Balance Combustion Reactions

Practice Problem: Balancing Equations

Balancing more complex chemical equations | Chemical reactions | High school chemistry |Khan Academy

Balancing Chemical Equations With Fractions | How to Pass Chemistry

GCSE Chemistry - Balancing Chemical Equations #4

Rate This

5.0 / 5 (0 votes)

Thanks for rating:

Related Tags
Chemical ReactionCombustionEthaneOxygenBalancingEducationScienceChemistryEquationTeaching