Gr 9 NATURAL SCIENCES: CH 2.2 How do we represent chemical reactions?
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Questions and Answers

What is the purpose of representing chemical reactions?

  • To calculate the amount of reactants required
  • To identify the products of a reaction
  • To understand how substances interact and transform (correct)
  • To understand the properties of reactants

What is a chemical equation?

  • A symbolic representation of a chemical reaction using chemical names
  • A visual representation of a chemical reaction using diagrams
  • A symbolic representation of a chemical reaction using chemical formulae (correct)
  • A description of a chemical reaction in words

What is the purpose of a subscript in a chemical formula?

  • To indicate the type of bond between atoms
  • To indicate the physical state of a substance
  • To indicate the number of molecules involved
  • To indicate the number of atoms of an element in a molecule (correct)

What is a reactant in a chemical reaction?

<p>A substance that undergoes change during the reaction (A)</p> Signup and view all the answers

What is the purpose of a word equation?

<p>To represent a chemical reaction using the names of the reactants and products (D)</p> Signup and view all the answers

What is the purpose of a coefficient in a chemical equation?

<p>To indicate the number of molecules or atoms involved (C)</p> Signup and view all the answers

What do picture equations use to visually represent chemical reactions?

<p>Submicroscopic diagrams (C)</p> Signup and view all the answers

What is the purpose of coefficients in chemical equations?

<p>To indicate the number of molecules involved (D)</p> Signup and view all the answers

What do subscripts represent in chemical equations?

<p>The number of atoms of each element in a molecule (B)</p> Signup and view all the answers

What is the reactant in the chemical equation 2H₂ + O₂ → 2H₂O?

<p>Both Hâ‚‚ and Oâ‚‚ (C)</p> Signup and view all the answers

What is the product in the chemical equation 2H₂ + O₂ → 2H₂O?

<p>Hâ‚‚O (D)</p> Signup and view all the answers

What does the coefficient '2' indicate in the chemical equation 2H₂ + O₂ → 2H₂O?

<p>Two molecules of hydrogen involved (A)</p> Signup and view all the answers

What does the subscript '2' indicate in the chemical formula Hâ‚‚O?

<p>Two atoms of hydrogen in each molecule (A)</p> Signup and view all the answers

What is the purpose of chemical equations?

<p>To represent the reactants and products using chemical symbols and formulae (C)</p> Signup and view all the answers

What is the arrow (→) used for in chemical equations?

<p>To separate the reactants and products (D)</p> Signup and view all the answers

What is the number of oxygen molecules involved in the reaction 2H₂ + O₂ → 2H₂O?

<p>1 (A)</p> Signup and view all the answers

What does the subscript '2' indicate in the chemical formula Hâ‚‚?

<p>Two atoms of hydrogen (C)</p> Signup and view all the answers

In the chemical equation 2H₂ + O₂ → 2H₂O, what is the number of hydrogen atoms in each molecule of water?

<p>2 (D)</p> Signup and view all the answers

What is the total number of hydrogen atoms involved in the reaction 2H₂ + O₂ → 2H₂O?

<p>4 (D)</p> Signup and view all the answers

What is the purpose of the arrow (→) in a chemical equation?

<p>To separate the reactants from the products (B)</p> Signup and view all the answers

In the chemical equation 2H₂ + O₂ → 2H₂O, what is the total number of oxygen atoms involved?

<p>2 (A)</p> Signup and view all the answers

What does the coefficient '2' indicate in the chemical equation 2H₂ + O₂ → 2H₂O?

<p>Two molecules of hydrogen (C)</p> Signup and view all the answers

In the chemical equation 2H₂ + O₂ → 2H₂O, what is the total number of water molecules produced?

<p>2 (A)</p> Signup and view all the answers

What is the primary difference between a word equation and a chemical equation?

<p>The level of detail provided about the reactants and products (B)</p> Signup and view all the answers

Which of the following represents a chemical reaction?

<p>A rearrangement of atoms in which one or more compounds are transformed into new compounds (B)</p> Signup and view all the answers

What is the role of a coefficient in a chemical equation?

<p>To indicate the number of molecules or atoms involved (A)</p> Signup and view all the answers

Which of the following is a characteristic of a picture equation?

<p>Uses submicroscopic diagrams to visually represent reactants and products (A)</p> Signup and view all the answers

What is the purpose of using subscripts in chemical formulae?

<p>To indicate the number of atoms of an element in a molecule (C)</p> Signup and view all the answers

Which of the following statements is true about reactants and products?

<p>Reactants are present before the reaction, and products are formed as a result of the reaction (C)</p> Signup and view all the answers

What is the advantage of using chemical equations over word equations?

<p>Chemical equations provide more detailed information about the reactants and products (C)</p> Signup and view all the answers

What is the primary purpose of a subscript in a chemical formula?

<p>To indicate the number of atoms of an element in a molecule (B)</p> Signup and view all the answers

What is the key difference between a reactant and a product in a chemical reaction?

<p>Reactants are the substances present before the reaction, while products are the substances formed during the reaction. (C)</p> Signup and view all the answers

What is the primary advantage of using chemical equations over word equations?

<p>Chemical equations provide more detailed information about the reactants and products (C)</p> Signup and view all the answers

What is the purpose of a coefficient in a chemical equation?

<p>To balance the number of atoms of each element on both sides of the equation (D)</p> Signup and view all the answers

What is the primary characteristic of a picture equation?

<p>It uses submicroscopic diagrams to visually represent the reactants and products (A)</p> Signup and view all the answers

What is the primary difference between a chemical equation and a word equation?

<p>A chemical equation provides more detailed information about the reactants and products (B)</p> Signup and view all the answers

What is the primary role of a reactant in a chemical reaction?

<p>To undergo a change in composition during the reaction (C)</p> Signup and view all the answers

What is the total number of hydrogen atoms involved in the reaction 3H₂ + O₂ → 2H₂O?

<p>6 (A)</p> Signup and view all the answers

What does the subscript '3' indicate in the chemical formula NO₃?

<p>Three atoms of oxygen are present in each molecule of NO₃ (D)</p> Signup and view all the answers

In the chemical equation Ca + O₂ → 2CaO, what is the role of the coefficient '2'?

<p>It indicates the number of calcium oxide molecules produced in the reaction (B)</p> Signup and view all the answers

In the chemical equation 2H₂ + O₂ → 2H₂O, what is the ratio of hydrogen molecules to oxygen molecules?

<p>2:1 (B)</p> Signup and view all the answers

What is the total number of oxygen atoms involved in the reaction 2H₂ + O₂ → 2H₂O?

<p>2 (B)</p> Signup and view all the answers

In the chemical equation 2H₂ + O₂ → 2H₂O, what is the number of water molecules produced per oxygen molecule?

<p>2 (B)</p> Signup and view all the answers

What is the purpose of writing chemical equations?

<p>To represent the reactants and products in a symbolic format (B)</p> Signup and view all the answers

In the chemical equation CO + O₂ → CO₂, what is the role of the coefficient '1'?

<p>It is not explicitly indicated in the equation (A)</p> Signup and view all the answers

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