Gr 9 NATURAL SCIENCES: CH 2.2 Balanced equations
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Questions and Answers

What is the first step to balance the equation Mg + O2 → MgO?

  • Change the subscripts of Mg and O
  • Add O2 to the product side
  • Add a coefficient of 2 to MgO (correct)
  • Change the coefficient of Mg to 2

    • What is a crucial rule to follow when balancing equations?

  • Modify the given reactants and products
  • Change only the coefficients of chemical formulas (correct)
  • Change the subscripts of chemical formulas
  • Add or remove reactants or products

    • What is the purpose of balancing an equation?

  • To make the equation look visually appealing
  • To modify the subscripts of chemical formulas
  • To ensure the same number of atoms of each element on both sides (correct)
  • To change the reactants and products

    • In the balanced equation CH4 + 2O2 → CO2 + 2H2O, what is the coefficient of O2?

    <p>2</p> Signup and view all the answers

    In the balanced equation 2H2 + O2 → 2H2O, what is the coefficient of H2?

    <p>2</p> Signup and view all the answers

    What should not be changed when balancing an equation?

    <p>Subscripts of chemical formulas</p> Signup and view all the answers

    Why is it important to balance an equation?

    <p>To satisfy the law of conservation of mass</p> Signup and view all the answers

    What is the result of balancing an equation?

    <p>The same number of atoms of each element on both sides</p> Signup and view all the answers

    What does a balanced equation represent in chemistry?

    <p>The law of conservation of mass</p> Signup and view all the answers

    What is the term for a representation of a substance using symbols for its constituent elements?

    <p>Chemical formula</p> Signup and view all the answers

    What is the process of counting atoms on both sides of a chemical equation to ensure they are equal?

    <p>Counting the atoms</p> Signup and view all the answers

    What happens when a metal reacts with oxygen or sulfur?

    <p>It becomes tarnish</p> Signup and view all the answers

    What is the correct statement about the equation 2H₂ + O₂ → 2H₂O?

    <p>It is a balanced equation</p> Signup and view all the answers

    What is the first step in balancing a chemical equation?

    <p>Counting the atoms on both sides of the equation</p> Signup and view all the answers

    What is the definition of a balanced equation?

    <p>An equation where the number and type of atoms are the same on both sides</p> Signup and view all the answers

    What is the primary reason for balancing chemical equations?

    <p>To ensure the same number of atoms of each element on both sides of the equation</p> Signup and view all the answers

    What is the term for the dulling or discoloration of metal due to a chemical reaction?

    <p>Tarnish</p> Signup and view all the answers

    In the balanced equation 2H₂ + O₂ → 2H₂O, what is the number of oxygen atoms on the left side of the equation?

    <p>2</p> Signup and view all the answers

    What is the result of balancing the equation Mg + O₂ → MgO?

    <p>The number and type of atoms are the same on both sides of the equation</p> Signup and view all the answers

    What is the term for iron oxide, formed by the reaction of iron and oxygen?

    <p>Rust</p> Signup and view all the answers

    What is the first step in balancing the equation Mg + O₂ → MgO?

    <p>Counting the atoms on both sides of the equation</p> Signup and view all the answers

    What is a characteristic of a balanced equation?

    <p>The number and type of atoms are the same on both sides of the equation</p> Signup and view all the answers

    When balancing an equation, what is the primary goal?

    <p>To ensure the number of atoms of each element is equal on both sides</p> Signup and view all the answers

    In the combustion of methane, what is the coefficient of O2 in the balanced equation?

    <p>2</p> Signup and view all the answers

    What is the result of balancing the equation H2 + O2 → H2O?

    <p>2H2 + O2 → 2H2O</p> Signup and view all the answers

    What should be modified to balance an equation?

    <p>The coefficients in front of the chemical formulas</p> Signup and view all the answers

    In the equation 2Mg + O2 → 2MgO, what is the coefficient of Mg?

    <p>2</p> Signup and view all the answers

    What is the purpose of using coefficients in balancing an equation?

    <p>To ensure the number of atoms of each element is equal on both sides</p> Signup and view all the answers

    What is the correct sequence of steps to balance an equation?

    <p>Modify the coefficients only</p> Signup and view all the answers

    What is the significance of a balanced equation in chemistry?

    <p>It represents the correct ratio of reactants and products</p> Signup and view all the answers

    Which of the following is a necessary condition for a chemical equation to be balanced?

    <p>The number of atoms of each element is equal on both sides of the equation.</p> Signup and view all the answers

    What is the primary reason for ensuring that a chemical equation is balanced?

    <p>To ensure that the law of conservation of mass is obeyed.</p> Signup and view all the answers

    In a balanced equation, what is the relationship between the number of atoms of each element on the reactant and product sides?

    <p>The number of atoms of each element is equal on both sides.</p> Signup and view all the answers

    What is the purpose of counting the atoms of each element on both sides of a chemical equation?

    <p>To ensure that the equation is balanced.</p> Signup and view all the answers

    Which of the following statements is true about a balanced equation?

    <p>The equation represents the conservation of mass.</p> Signup and view all the answers

    What is the result of balancing a chemical equation?

    <p>The number of atoms of each element is equal on both sides of the equation.</p> Signup and view all the answers

    Which of the following is an example of a chemical reaction that involves the tarnishing of a metal?

    <p>The rusting of iron.</p> Signup and view all the answers

    What is the primary reason for modifying the coefficients of reactants or products in a chemical equation?

    <p>To ensure the equation is balanced</p> Signup and view all the answers

    Which of the following is a correct statement about balancing a chemical equation?

    <p>Coefficients can be added to or modified to balance the equation</p> Signup and view all the answers

    What is a common mistake to avoid when balancing a chemical equation?

    <p>Changing the subscripts of reactants</p> Signup and view all the answers

    In the balanced equation CH₄ + 2O₂ → CO₂ + 2H₂O, what is the significance of the coefficient 2 in front of O₂?

    <p>It indicates the number of oxygen atoms required to balance the equation</p> Signup and view all the answers

    What is the primary goal of balancing a chemical equation?

    <p>To ensure the number of atoms of each element is equal on both sides</p> Signup and view all the answers

    In the balanced equation 2H₂ + O₂ → 2H₂O, what is the significance of the coefficient 2 in front of H₂?

    <p>It indicates the number of hydrogen atoms required to balance the equation</p> Signup and view all the answers

    What is the result of balancing the equation Mg + O₂ → MgO?

    <p>The coefficients of the reactants are modified</p> Signup and view all the answers

    What is the correct sequence of steps to balance a chemical equation?

    <p>Modify the coefficients, without changing the subscripts or adding/removing reactants/products</p> Signup and view all the answers

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