Gr 9 NATURAL SCIENCES: CH 2.2 SUM Chemical Reactions

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Questions and Answers

What is the purpose of representing chemical reactions?

  • To represent the macroscopic level
  • To understand the composition of matter
  • To represent the submicroscopic level
  • To understand how substances interact and transform (correct)

What is a chemical equation?

  • A symbolic representation of a chemical reaction using chemical names
  • A symbolic representation of a chemical reaction using chemical formulae (correct)
  • A macroscopic representation of a chemical reaction
  • A submicroscopic representation of a chemical reaction

What is a coefficient in a chemical equation?

  • A symbol used to represent a product
  • A small number written below and to the right of a chemical symbol
  • A number placed in front of a chemical formula (correct)
  • A symbol used to represent a reactant

What is a subscript in a chemical formula?

<p>A small number written below and to the right of a chemical symbol (A)</p> Signup and view all the answers

What is a reactant in a chemical reaction?

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

What is a product in a chemical reaction?

<p>A substance formed as a result of the reaction (A)</p> Signup and view all the answers

What is the level of representation that uses chemical symbols and formulae?

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

What is a word equation?

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

What is a picture equation?

<p>A visual representation of a chemical reaction using submicroscopic diagrams (D)</p> Signup and view all the answers

What do coefficients in chemical equations indicate?

<p>The number of molecules or atoms involved (D)</p> Signup and view all the answers

What is the purpose of subscripts in chemical formulae?

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

What is a balanced equation?

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

Why is it important to balance chemical equations?

<p>To accurately represent the conservation of mass (C)</p> Signup and view all the answers

What is the correct way to balance a chemical equation?

<p>Change the coefficients in front of the chemical formulae (A)</p> Signup and view all the answers

What is the rule for balancing chemical equations regarding subscripts?

<p>Do not change the subscripts (D)</p> Signup and view all the answers

What is the purpose of counting atoms in a chemical equation?

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

What happens when a chemical equation is not balanced?

<p>The equation does not represent the conservation of mass (A)</p> Signup and view all the answers

Why is it important to balance a chemical equation step by step?

<p>To ensure accuracy (C)</p> Signup and view all the answers

What is the result of balancing a chemical equation?

<p>An equation with the same number and type of atoms on both sides (B)</p> Signup and view all the answers

What is the definition of a bond in chemistry?

<p>A force that holds atoms together in a molecule or compound (D)</p> Signup and view all the answers

At which level can we observe substances and their changes with our senses?

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

What is the definition of a reactant in chemistry?

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

What is the definition of a product in chemistry?

<p>A substance that is formed as a result of a chemical reaction (A)</p> Signup and view all the answers

What is the definition of a chemical reaction?

<p>A process in which substances are transformed into different substances through the breaking and forming of chemical bonds (A)</p> Signup and view all the answers

At which level do we visualize or imagine the particles that make up substances?

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

What is the definition of the macroscopic level?

<p>The level at which we can observe substances and their changes with our senses (A)</p> Signup and view all the answers

What is the level at which we represent substances using chemical symbols and formulae?

<p>Symbolic level (C)</p> Signup and view all the answers

What is the definition of the submicroscopic level?

<p>The level at which we visualize or imagine particles that make up substances (C)</p> Signup and view all the answers

What is the purpose of the three levels of representation in chemistry?

<p>To help scientists understand chemical reactions (D)</p> Signup and view all the answers

What is the result of the breaking and forming of chemical bonds during a chemical reaction?

<p>The transformation of substances into different substances (C)</p> Signup and view all the answers

Which level of representation involves observing substances and their changes with our senses?

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

What is the main difference between the macroscopic and submicroscopic levels?

<p>The ability to observe with our senses (B)</p> Signup and view all the answers

What is the purpose of using the three levels of representation in chemistry?

<p>To understand and describe the changes that occur during chemical reactions (C)</p> Signup and view all the answers

What is true about the submicroscopic level?

<p>It involves imagining or visualizing particles (B)</p> Signup and view all the answers

What is common to both the macroscopic and symbolic levels?

<p>Involves describing chemical reactions (A)</p> Signup and view all the answers

What is an example of a macroscopic observation?

<p>Observing the bubbling of a liquid (D)</p> Signup and view all the answers

What is true about the symbolic level?

<p>It involves representing substances using chemical symbols and formulae (C)</p> Signup and view all the answers

What is the main difference between the symbolic and submicroscopic levels?

<p>The way particles are represented (C)</p> Signup and view all the answers

What is true about chemical bonds?

<p>They are broken and formed during chemical reactions (B)</p> Signup and view all the answers

What does the coefficient '2' in front of H₂ in the equation 2H₂ + O₂ → 2H₂O represent?

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

What is the purpose of balancing a chemical equation?

<p>To represent the conservation of mass (D)</p> Signup and view all the answers

What is the correct way to balance a chemical equation?

<p>Change the coefficients in front of the chemical formulas (B)</p> Signup and view all the answers

What is the result of counting atoms in a chemical equation?

<p>To verify if the equation is balanced (A)</p> Signup and view all the answers

What is the rule for balancing chemical equations regarding subscripts?

<p>Do not change the subscripts (C)</p> Signup and view all the answers

What is the purpose of using coefficients in chemical equations?

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

What happens when a chemical equation is not balanced?

<p>The number of atoms of each element is not the same on both sides of the equation (C)</p> Signup and view all the answers

What is the importance of balancing chemical equations step by step?

<p>To ensure the equation is accurate and precise (A)</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 the same on both sides of the equation (A)</p> Signup and view all the answers

What is the definition of a balanced equation?

<p>An equation where the number of atoms of each element is the same on both sides (C)</p> Signup and view all the answers

What is the primary purpose of the three levels of representation in chemistry?

<p>To visualize and communicate chemical reactions and transformations (D)</p> Signup and view all the answers

What is the advantage of using the symbolic level of representation?

<p>It enables us to communicate chemical reactions using a concise and universal language (D)</p> Signup and view all the answers

Which of the following is an example of a picture equation?

<p>A diagram showing hydrogen and oxygen atoms rearranging to form water molecules (D)</p> Signup and view all the answers

What is the difference between the reactants and products in a chemical reaction?

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

What is the role of coefficients in a chemical equation?

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

Which of the following is an example of a word equation?

<p>Hydrogen + oxygen → water (D)</p> Signup and view all the answers

What is the level of representation that uses diagrams to show the arrangement of atoms in a molecule?

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

What is the purpose of the macroscopic level of representation?

<p>To observe and describe the physical properties of a substance (D)</p> Signup and view all the answers

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

<p>A chemical equation uses symbols and formulae, while a word equation uses the names of the reactants and products (B)</p> Signup and view all the answers

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

<p>A picture equation uses diagrams, while a chemical equation uses symbols and formulae (D)</p> Signup and view all the answers

What is the primary reason scientists use the three levels of representation in understanding chemical reactions?

<p>To describe the changes that occur during chemical reactions (D)</p> Signup and view all the answers

Which level of representation involves the use of models or simulations to understand the particles that make up substances?

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

What is the key characteristic that distinguishes the macroscopic level of representation from the submicroscopic level?

<p>The ability to observe changes with our senses (D)</p> Signup and view all the answers

What is the primary advantage of using the three levels of representation in understanding chemical reactions?

<p>It provides a comprehensive understanding of chemical reactions (A)</p> Signup and view all the answers

Which of the following is an example of a macroscopic observation?

<p>The color change of a solution during a reaction (C)</p> Signup and view all the answers

What is the primary purpose of the symbolic level of representation?

<p>To represent substances using chemical symbols and formulae (B)</p> Signup and view all the answers

What is the key characteristic that distinguishes the symbolic level of representation from the submicroscopic level?

<p>The use of chemical symbols and formulae (B)</p> Signup and view all the answers

What is the result of the breaking and forming of chemical bonds during a chemical reaction?

<p>The formation of new substances (C)</p> Signup and view all the answers

Which level of representation is most closely related to the concept of chemical bonds?

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

What is the primary advantage of using multiple levels of representation in understanding chemical reactions?

<p>It provides a comprehensive and nuanced understanding of chemical reactions (B)</p> Signup and view all the answers

What is the primary function of coefficients in a chemical equation?

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

Which of the following representations is least suitable for understanding the chemical properties of a substance?

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

What is the primary purpose of using coefficients in a chemical equation?

<p>To indicate the number of molecules involved in a reaction (A)</p> Signup and view all the answers

What is the purpose of counting atoms in a chemical equation?

<p>To determine if the equation is balanced (B)</p> Signup and view all the answers

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

<p>The reactants and products are represented differently (B)</p> Signup and view all the answers

What is the rule for balancing chemical equations regarding subscripts?

<p>Do not change the subscripts (D)</p> Signup and view all the answers

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

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

What is the purpose of using subscripts in a chemical formula?

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

Which of the following is a characteristic of a chemical reaction?

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

What is the purpose of using the three levels of representation in chemistry?

<p>To provide a clear understanding of chemical reactions (D)</p> Signup and view all the answers

What is the primary purpose of using the three levels of representation in chemistry?

<p>To provide a comprehensive understanding of chemical reactions and substances (D)</p> Signup and view all the answers

What is the result of the breaking and forming of chemical bonds during a chemical reaction?

<p>The formation of new compounds (C)</p> Signup and view all the answers

What is the key to balancing a chemical equation step by step?

<p>Changing only the coefficients (B)</p> Signup and view all the answers

What is the result of not balancing a chemical equation?

<p>The equation does not accurately represent the conservation of mass (C)</p> Signup and view all the answers

Which of the following is a characteristic of the symbolic level of representation?

<p>It uses chemical symbols and formulae to represent substances and their changes (A)</p> Signup and view all the answers

What is the main difference between the macroscopic and submicroscopic levels of representation?

<p>The macroscopic level involves observing substances and their changes with our senses, while the submicroscopic level involves visualizing or imagining the particles that make up substances (D)</p> Signup and view all the answers

What is the importance of balancing chemical equations?

<p>It accurately represents the conservation of mass (A)</p> Signup and view all the answers

What is the primary purpose of using picture equations?

<p>To provide a visual representation of the reactants and products in a chemical reaction (B)</p> Signup and view all the answers

Which of the following is a characteristic of the submicroscopic level of representation?

<p>Smaller than microscopic; too small to be seen with a microscope (B)</p> Signup and view all the answers

What is the main purpose of the three levels of representation in chemistry?

<p>To approach understanding chemical reactions on different levels (D)</p> Signup and view all the answers

What occurs during a chemical reaction?

<p>Breaking and forming of chemical bonds (D)</p> Signup and view all the answers

What is an example of a macroscopic observation?

<p>Observing water in a beaker (A)</p> Signup and view all the answers

What is true about chemical bonds?

<p>They hold atoms together in a molecule or compound (B)</p> Signup and view all the answers

What is the level of representation that involves representing substances using chemical symbols and formulae?

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

What is the primary purpose of using coefficients in chemical equations?

<p>To balance the number of atoms on both sides of a chemical equation (B)</p> Signup and view all the answers

What is the difference between a subscript and a coefficient in a chemical equation?

<p>A subscript represents the number of atoms in a molecule, while a coefficient represents the number of molecules (B)</p> Signup and view all the answers

When balancing a chemical equation, what should be changed to balance the number of atoms?

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

What is the result of counting atoms in a chemical equation?

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

Why is it important to balance chemical equations step by step?

<p>To ensure the correct number and type of atoms on both sides of the equation (B)</p> Signup and view all the answers

What is the definition of a balanced equation?

<p>An equation with the same number and type of atoms on both sides (C)</p> Signup and view all the answers

What is the rule for balancing chemical equations regarding subscripts?

<p>Do not change the subscripts when balancing the equation (C)</p> Signup and view all the answers

What happens when a chemical equation is not balanced?

<p>The number of atoms on both sides of the equation is not equal (A)</p> Signup and view all the answers

What is the primary reason why experienced scientists can easily move between the three levels of representation?

<p>They can translate between symbolic notation and submicroscopic representations (B)</p> Signup and view all the answers

Which of the following is a characteristic of the symbolic level of representation?

<p>It uses chemical symbols and formulae to represent substances and reactions (C)</p> Signup and view all the answers

What is the primary purpose of using word equations, picture equations, and chemical equations to represent chemical reactions?

<p>To describe the reactants and products involved in a reaction (A)</p> Signup and view all the answers

Which level of representation is most closely related to the molecular structure of a substance?

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

What is the primary advantage of using chemical equations to represent chemical reactions?

<p>They allow for the quantification of reactants and products (B)</p> Signup and view all the answers

What is the main difference between the macroscopic and submicroscopic levels of representation?

<p>The macroscopic level involves observing substances with our senses, while the submicroscopic level involves imagining the particles that make up substances (B)</p> Signup and view all the answers

What does a coefficient in a chemical equation represent?

<p>The number of molecules of a substance involved in a reaction (A)</p> Signup and view all the answers

What is the purpose of balancing a chemical equation?

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

What is the significance of subscripts in chemical formulae?

<p>They show the number of atoms of an element in a molecule (D)</p> Signup and view all the answers

What is the rule for balancing chemical equations regarding coefficients?

<p>Modify the coefficients in front of chemical formulae to balance the equation (D)</p> Signup and view all the answers

What happens when a chemical equation is not balanced?

<p>The law of conservation of mass is violated (A)</p> Signup and view all the answers

What is the result of counting atoms in a chemical equation?

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

Why is it important to balance chemical equations step by step?

<p>To ensure the law of conservation of mass is upheld (A)</p> Signup and view all the answers

What is the primary purpose of using coefficients in chemical equations?

<p>To indicate the number of molecules of a substance involved in a reaction (A)</p> Signup and view all the answers

Which level of representation involves the use of chemical symbols and formulae to describe substances and their transformations?

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

What is the purpose of the coefficient '2' in front of H₂ in the equation 2H₂ + O₂ → 2H₂O?

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

What is the main difference between the macroscopic and submicroscopic levels of representation?

<p>The macroscopic level involves observing substances with our senses, while the submicroscopic level involves visualizing particles that make up substances (D)</p> Signup and view all the answers

What is the result of the reaction between hydrogen gas and oxygen gas?

<p>Formation of water (D)</p> Signup and view all the answers

What is the purpose of representing chemical reactions using word equations, picture equations, and chemical equations?

<p>To understand how substances interact and transform (A)</p> Signup and view all the answers

What is the primary purpose of the three levels of representation in chemistry?

<p>To understand how substances interact and transform (C)</p> Signup and view all the answers

What is the main difference between the macroscopic and submicroscopic levels of representation?

<p>One involves observing substances, while the other involves visualizing particles. (C)</p> Signup and view all the answers

What is the result of the breaking and forming of chemical bonds during a chemical reaction?

<p>The transformation of substances into different substances. (D)</p> Signup and view all the answers

What is the purpose of the three levels of representation in chemistry?

<p>To help scientists visualize and describe the changes that occur during chemical reactions. (C)</p> Signup and view all the answers

What is true about the submicroscopic level of representation?

<p>It involves visualizing particles that make up substances. (C)</p> Signup and view all the answers

What is an example of a macroscopic observation?

<p>The formation of a solid precipitate. (D)</p> Signup and view all the answers

What is true about chemical bonds?

<p>They are the force that holds atoms together in a molecule or compound. (B)</p> Signup and view all the answers

What occurs during a chemical reaction?

<p>The breaking and forming of chemical bonds occur (B)</p> Signup and view all the answers

Which level of representation involves visualizing particles that make up substances?

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

What is the primary feature of the macroscopic level?

<p>It is observable with the naked eye (C)</p> Signup and view all the answers

What is the result of the breaking and forming of chemical bonds during a chemical reaction?

<p>Substances are transformed into different substances (B)</p> Signup and view all the answers

What is the definition of a bond in chemistry?

<p>The force that holds atoms together in a molecule or compound (A)</p> Signup and view all the answers

Which of the following is an example of a macroscopic observation?

<p>Observing the bubbling of a liquid (A)</p> Signup and view all the answers

What is the main advantage of using the symbolic level of representation in chemistry?

<p>It provides a concise way to describe chemical reactions (C)</p> Signup and view all the answers

Which level of representation involves visualizing or imagining the particles that make up substances?

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

What is the purpose of using coefficients in chemical equations?

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

What is the result of the reaction between hydrogen gas and oxygen gas?

<p>Water and steam (C)</p> Signup and view all the answers

What is the primary purpose of representing chemical reactions?

<p>To understand how substances interact and transform (D)</p> Signup and view all the answers

Which level of representation involves observing substances and their changes with our senses?

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

What does the coefficient '2' in front of H₂ in the equation 2H₂ + O₂ → 2H₂O represent?

<p>Two molecules of hydrogen are involved in the reaction (B)</p> Signup and view all the answers

What is the purpose of balancing a chemical equation?

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

What happens when a chemical equation is not balanced?

<p>The number of atoms of each element will not be conserved (B)</p> Signup and view all the answers

What is true about the submicroscopic level?

<p>It involves visualizing or imagining the particles that make up substances (A)</p> Signup and view all the answers

What is the primary purpose of using coefficients in chemical equations?

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

What is true about the rule for balancing chemical equations regarding subscripts?

<p>Subscripts should not be changed to balance the equation (B)</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 the same on both sides of the equation (C)</p> Signup and view all the answers

What is the importance of balancing chemical equations step by step?

<p>It ensures the number of atoms of each element is conserved (D)</p> Signup and view all the answers

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