Gr 8 Natural Sciences Ch 2.3: How do we know a chemical reaction has taken place?
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Questions and Answers

What is the definition of a chemical reaction?

  • A process in which substances change their physical properties
  • A process in which substances change their colour
  • A process in which substances are transformed into new substances with different chemical properties (correct)
  • A process in which substances remain the same

What is a reaction flask or reaction vessel?

  • A container used to mix substances
  • A container used to carry out a chemical reaction (correct)
  • A container used to heat substances
  • A container used to store chemicals

What is an indication of a chemical reaction?

  • A change in colour (correct)
  • A change in shape
  • A change in size
  • A change in smell

What is a sign of gas formation in a chemical reaction?

<p>The presence of bubbles (A)</p> Signup and view all the answers

What is the term for the solid material formed in a chemical reaction?

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

How can we identify a chemical reaction using our sense of smell?

<p>By smelling new substances with distinct smells (B)</p> Signup and view all the answers

What is an example of an exothermic reaction?

<p>A reaction between acid and base (D)</p> Signup and view all the answers

What is an example of a chemical reaction that produces a sound?

<p>A reaction that produces fizzing or explosions (B)</p> Signup and view all the answers

What is responsible for the fizzing sound in the reaction of baking soda and vinegar?

<p>Release of carbon dioxide gas (C)</p> Signup and view all the answers

What is the purpose of the vinegar in the eggshell removal experiment?

<p>To react with the calcium carbonate in the eggshell (B)</p> Signup and view all the answers

What happens to the particles of the reactants during a chemical reaction?

<p>They break their bonds and form new bonds (D)</p> Signup and view all the answers

What is the product of the reaction between calcium carbonate and acetic acid?

<p>Calcium acetate and carbon dioxide gas (D)</p> Signup and view all the answers

What is the result of the reaction between the eggshell and vinegar?

<p>The eggshell dissolves (B)</p> Signup and view all the answers

What is the purpose of the glass or container in the eggshell removal experiment?

<p>To hold the egg (C)</p> Signup and view all the answers

Which of the following is a visual sign of a chemical reaction?

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

What is the primary purpose of a reaction flask or reaction vessel?

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

Which of the following is an example of a chemical reaction that produces a gas?

<p>The reaction between hydrochloric acid and sodium hydroxide (A)</p> Signup and view all the answers

What is the term for the heat released during a chemical reaction?

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

Which of the following senses is NOT used to identify a chemical reaction?

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

What is the primary indicator of a colour change in a chemical reaction?

<p>A change in the hue of the colour (B)</p> Signup and view all the answers

What is the term for the transformation of substances into new substances with different chemical properties?

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

Which of the following is a common indicator of a chemical reaction that produces a solid?

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

What is the role of calcium acetate in the reaction between the eggshell and vinegar?

<p>It is a byproduct of the reaction that helps to dissolve the eggshell. (D)</p> Signup and view all the answers

What is the purpose of observing the reaction over 24-48 hours in the eggshell removal experiment?

<p>To ensure the eggshell is completely dissolved. (A)</p> Signup and view all the answers

What is the significance of the bubbles forming on the surface of the eggshell?

<p>They are a sign of gas formation, specifically carbon dioxide. (A)</p> Signup and view all the answers

What is the result of the rearrangement of atoms during a chemical reaction?

<p>The creation of substances with different properties from the original reactants. (D)</p> Signup and view all the answers

What is the role of the eggshell in the eggshell removal experiment?

<p>It is a reactant that reacts with the acetic acid. (D)</p> Signup and view all the answers

What type of bond is broken during a chemical reaction?

<p>All of the above. (D)</p> Signup and view all the answers

Which of the following is NOT a type of chemical reaction that can be identified through visual observation?

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

What is the primary difference between exothermic and endothermic reactions?

<p>The release or absorption of heat (D)</p> Signup and view all the answers

Which sense is most useful for identifying a chemical reaction that produces hydrogen sulfide gas?

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

What is the primary purpose of observing a chemical reaction over a period of time?

<p>To measure the rate of reaction (C)</p> Signup and view all the answers

Which of the following is an example of a chemical reaction that involves the breaking and forming of chemical bonds?

<p>Rusting of iron (B)</p> Signup and view all the answers

What is the term for the container used to carry out a chemical reaction?

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

Which of the following is NOT a sign of a chemical reaction?

<p>Dissolution of a solid (A)</p> Signup and view all the answers

What is the term for the new substances formed in a chemical reaction?

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

What is the primary driving force behind the formation of bubbles on the surface of the eggshell during the eggshell removal experiment?

<p>The increase in pressure from the accumulation of carbon dioxide gas (B)</p> Signup and view all the answers

Which of the following best describes the outcome of the reaction between the calcium carbonate in the eggshell and the acetic acid in the vinegar?

<p>A neutralization reaction that yields calcium acetate and water (A)</p> Signup and view all the answers

What is the significance of the 24-48 hour observation period in the eggshell removal experiment?

<p>To allow for the complete dissolution of the eggshell (D)</p> Signup and view all the answers

What is the role of the egg membrane in the eggshell removal experiment?

<p>To protect the egg from the acidic environment (C)</p> Signup and view all the answers

What is the primary function of the calcium acetate produced in the reaction between the eggshell and vinegar?

<p>To form a precipitate with the eggshell (D)</p> Signup and view all the answers

What is the net result of the rearrangement of atoms during a chemical reaction like the one between the eggshell and vinegar?

<p>A change in the chemical properties of the reactants (B)</p> Signup and view all the answers

What is the primary indicator of a chemical reaction that involves the formation of a gas?

<p>The presence of bubbles in the reaction flask (A)</p> Signup and view all the answers

Which sense is most useful for identifying a chemical reaction that produces a solid?

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

What is the primary purpose of using multiple senses to identify chemical reactions?

<p>To observe changes in the properties of the substances involved (D)</p> Signup and view all the answers

What is the term for the transformation of substances into new substances with different chemical properties?

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

Which of the following is NOT a type of observation that can indicate a chemical reaction has taken place?

<p>A change in the shape of the reactants (B)</p> Signup and view all the answers

What is the primary reason for the dissolution of the eggshell in the eggshell removal experiment?

<p>The vinegar reacts with the calcium carbonate in the eggshell. (C)</p> Signup and view all the answers

What is the role of the calcium acetate produced in the reaction between the eggshell and vinegar?

<p>It is one of the products of the reaction. (D)</p> Signup and view all the answers

What is the result of the rearrangement of atoms during a chemical reaction like the one between the eggshell and vinegar?

<p>The formation of new substances with different chemical properties. (C)</p> Signup and view all the answers

Why does the eggshell need to be observed over a period of 24-48 hours in the eggshell removal experiment?

<p>To allow sufficient time for the reaction to occur and the shell to dissolve. (C)</p> Signup and view all the answers

What is the significance of the bubbles forming on the surface of the eggshell during the eggshell removal experiment?

<p>It is a sign of gas formation during the reaction. (A)</p> Signup and view all the answers

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