Chemistry Chapter: Chemical Reactions Quiz
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Questions and Answers

Which of the following conditions is NOT necessary for a chemical reaction to occur?

  • Presence of a catalyst (correct)
  • Close contact between reactants
  • The formation of a new substance
  • A change in temperature

What is the purpose of storing sodium in kerosene oil?

  • To make the sodium easier to handle
  • To keep the sodium from oxidizing
  • To prevent the sodium from reacting with air
  • To prevent the sodium from reacting with water (correct)

In Activity 8, why does mixing solid sodium chloride and solid lead nitrate NOT result in a chemical reaction?

  • There is not enough surface area between the reactants
  • The reactants are not in a suitable form for reaction (correct)
  • The reactants are incompatible and cannot react
  • The reactants do not have enough energy to react

What is the chemical formula for the white precipitate formed in Activity 8?

<p>PbCl2 (A)</p> Signup and view all the answers

Which of the following is NOT an example of a chemical reaction in solution?

<p>The reaction between two gases (B)</p> Signup and view all the answers

What gas is produced when ammonium chloride is heated with sodium hydroxide?

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

Which gas is known for having a rotten egg smell when released during a chemical reaction?

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

In photosynthesis, is energy released or absorbed?

<p>Energy is absorbed in the form of heat and light (A)</p> Signup and view all the answers

Which of these describe a reaction that releases energy?

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

What process describes a reaction where energy is absorbed?

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

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

<p>To change the rate of the reaction without being consumed. (B)</p> Signup and view all the answers

In a chemical equation, which side are the reactants written on?

<p>The left-hand side (B)</p> Signup and view all the answers

Which of the following best describes the purpose of the arrow in a chemical equation?

<p>To point from reactants to products. (C)</p> Signup and view all the answers

Which of these is not a condition that can directly affect a chemical reaction?

<p>Volume of solution (D)</p> Signup and view all the answers

What is a reaction that require electricity in order to take place?

<p>The dissociation of water (A)</p> Signup and view all the answers

Which of the following is NOT a typical indication of a chemical reaction?

<p>Change in the state of matter (A)</p> Signup and view all the answers

In the reaction of sodium carbonate with dilute hydrochloric acid, what is the primary gas produced?

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

What does effervescence usually indicate in a chemical reaction?

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

Based on the examples provided, what usually happens to mercuric oxide when heated?

<p>It decomposes into mercury and oxygen (C)</p> Signup and view all the answers

Which of the following is NOT an example of a chemical reaction provided in the text?

<p>Water undergoing a phase change to steam at 100 $^\circ$C (A)</p> Signup and view all the answers

What are substances called that undergo a chemical change?

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

Which of the following best describes the outcome of a chemical reaction?

<p>Molecules rearrange to create one or more products. (D)</p> Signup and view all the answers

What do we call the new substances formed in a chemical reaction?

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

Which example illustrates a chemical reaction?

<p>Burning a candle (D)</p> Signup and view all the answers

What is involved in a chemical reaction besides the transformation of substances?

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

What observation indicates that a chemical reaction has occurred when iron is mixed with copper sulfate solution?

<p>A reddish-brown solid is formed. (C)</p> Signup and view all the answers

What is produced when sugar is heated in a porcelain dish?

<p>Sugar charcoal and water vapor. (B)</p> Signup and view all the answers

What observable change occurs when copper carbonate is heated?

<p>It turns into a black solid and releases gas. (A)</p> Signup and view all the answers

Which of the following describes a characteristic of chemical reactions involving gas evolution?

<p>Bubbles, smell, or color change can indicate gas production. (A)</p> Signup and view all the answers

What happens when zinc granules react with dilute hydrochloric acid?

<p>Bubbles are produced indicating gas evolution. (B)</p> Signup and view all the answers

What does a balanced chemical equation ensure about the atoms involved in a chemical reaction?

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

Which statement is true about skeletal equations?

<p>They represent reactions without needing balance. (B)</p> Signup and view all the answers

What is the purpose of using symbols and formulae in chemical equations?

<p>To save time and space while clearly showing reactions. (B)</p> Signup and view all the answers

Why is it necessary to use molecular forms like Hâ‚‚ and Clâ‚‚ for hydrogen and chlorine in chemical equations?

<p>To accurately reflect their natural existence in reactions. (C)</p> Signup and view all the answers

In a chemical reaction represented by the equation C + O₂ → CO₂, which statement is correct regarding the atom count?

<p>The number of oxygen atoms is greater in the products than in the reactants. (A)</p> Signup and view all the answers

What is the purpose of mixing baking soda with vinegar in the experiment?

<p>To evolve carbon dioxide gas (B)</p> Signup and view all the answers

What type of reaction occurs when potassium iodide is mixed with lead acetate?

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

Which observation indicates that a gas has been evolved in the baking soda and vinegar experiment?

<p>Formation of bubbles (C)</p> Signup and view all the answers

In the reaction involving barium chloride and sodium sulfate, what is the product formed?

<p>Barium sulfate precipitate (D)</p> Signup and view all the answers

What type of solid is produced during a precipitation reaction?

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

What is observed when hydrochloric acid reacts with ammonia?

<p>Generation of a white fume (B)</p> Signup and view all the answers

When hydrogen gas burns in oxygen, which of the following is produced?

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

What does effervescence indicate in a chemical reaction?

<p>A gas is being released (B)</p> Signup and view all the answers

Flashcards

Chemical Reaction

A process where two or more substances combine or break apart to form new substances with different properties.

How to Recognize a Chemical Reaction

A chemical reaction is often accompanied by a change in color, formation of gas, or heat release.

Reactants

The substances that are present at the beginning of a chemical reaction.

Products

The substances that are formed as a result of a chemical reaction.

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Exothermic Reaction

A chemical reaction that releases energy, usually in the form of heat.

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Chemical Equation

A way to represent chemical reactions using symbols and formulas. It shows the reactants and products involved.

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Balanced Chemical Equation

A chemical equation where the number of atoms of each element is the same on both sides of the equation.

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Skeletal Equation

A chemical equation that simply shows the reactants and products without balancing the number of atoms.

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Color Change Reaction

A chemical reaction where the color of the reactants or products changes.

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Evolution of a Gas

The production of a gas during a chemical reaction, observable by bubbles, smell, or color change.

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Sugar Charcoal

A black solid formed when sugar is heated, indicating a chemical change.

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Copper Carbonate

A green solid that turns black when heated, releasing carbon dioxide gas.

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Heating a Substance

The process of heating a substance to observe changes, often used in the context of chemical reactions.

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What is a catalyst?

A substance that changes the rate of a chemical reaction without itself undergoing any chemical change.

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What is a Chemical Equation?

A representation of a chemical reaction using symbols and formulas.

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What are Reactants in a Chemical Equation?

Substances that react in a chemical reaction.

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What are Products in a Chemical Equation?

Substances that are formed as a result of a chemical reaction.

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What factors affect chemical reactions?

Heat, light, electricity, or a catalyst can affect the rate of a chemical reaction.

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Endothermic Reactions

Chemical reactions where energy is absorbed from the surroundings, often resulting in a cooling effect.

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Change of Smell in Chemical Reactions

A change in the smell of substances can indicate a chemical reaction has occurred. This change is caused by the formation of new compounds with different odors.

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Change of Energy in Chemical Reactions

Chemical reactions often involve the release or absorption of energy, evident in the form of heat, light, or electricity. This energy change occurs as reactants transform into products.

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Energy Transformation in Chemical Reactions

Energy is released or absorbed in the form of heat, light, or electricity during the process of creating products from reactants in a chemical reaction.

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What is a chemical reaction?

A chemical reaction is any process where substances change into new substances with different properties. It always involves the transfer of energy.

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What are reactants?

The substances that undergo chemical change in a reaction are called reactants.

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What are products?

The new substances formed after a chemical reaction are called products.

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What happens to atoms in a reaction?

During a chemical reaction, atoms are not created or destroyed. They simply rearrange to form new substances.

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What are reactants and products made of?

Reactants and products are pure substances, meaning they have a fixed chemical composition. Examples include elements like hydrogen, oxygen, or compounds like water.

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Close Contact for Reactions

Reactants must be in close proximity and mixed together for a chemical reaction to happen.

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Chemical Reactions in Solutions

A solution is a mixture where one substance dissolves into another. Reactions can happen when mixing solutions because the dissolved particles have more chance to interact.

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What is a Precipitate?

A solid formed during a chemical reaction between solutions. It's usually a different substance from the original solutions.

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Why do we see a precipitate?

Chemical reactions in solutions can create new solids that are different from the original solutions. These solids don't dissolve, making them visible as precipitates.

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Why don't solid reactants always react?

When mixing solids directly, they might not react because the particles aren't close enough or moving around enough to interact.

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What is carbon dioxide?

This is a gas produced in a chemical reaction and can be observed as bubbles.

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What forms when a substance is insoluble?

This is a solid formed in a chemical reaction, usually appearing as a cloudy substance in the liquid.

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Whats the change of state in chemistry?

This is the change of a substance from one physical state to another, such as solid to liquid or liquid to gas. It is a common observation in chemical reactions.

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What is the reaction between ammonia and hydrochloric acid?

This is the reaction between ammonia (a gas) and hydrochloric acid (a liquid). It's easy to see because it forms a white fume.

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What is evolution of gas in a chemical reaction?

A chemical reaction that produces noticeable bubbles and a visible change is often a sign this is happening.

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What is a change of color in a reaction?

This is the change in color that usually means a new substance was formed during the chemical reaction.

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When two liquids are mixed, what is formed?

This is a reaction in which a new solid insoluble substance is formed and can be seen as a cloudy substance.

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What is exothermic?

This is a reaction that generates a lot of heat, it's easy to tell because it's hot.

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Study Notes

Chemical Reactions

  • Chemical reactions involve a change in matter resulting in one or more new substances.
  • Energy transfer also occurs during chemical reactions.
  • Example of a chemical reaction: burning a candle. Wax burns in air to produce carbon dioxide and water vapour, and releases light and heat energy.
  • Substances undergoing a chemical change are called reactants.
  • The new substances produced are called products.
  • Both reactants and products are pure substances.

Conditions Necessary for Chemical Reactions

  • Close contact: Reactants need to come in close contact (mixed together) for a reaction to occur.
  • Example: Sodium reacts with water violently when they come into contact.

Change of Energy

  • Chemical reactions are often accompanied by a change in energy.
  • Energy can be released (exothermic) or absorbed (endothermic).
  • Energy can be in the form of heat, light, or electricity.
  • Example of an exothermic reaction: Burning of Magnesium.
  • Example of an endothermic reaction: Photosynthesis.

Catalyst

  • A catalyst is a substance that speeds up or slows down a chemical reaction without changing itself.
  • Different chemical substances are used as catalysts in different chemical reactions.

Chemical Equations

  • Chemical equations use symbols to represent elements and compounds in a reaction.
  • Reactants are written on the left side of the equation and products on the right-hand side.
  • An arrow points from reactants to products.
  • Example: Reactants (A) + (B) → Products (C) + (D).

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Test your knowledge on chemical reactions with this quiz. Questions cover essential concepts such as reactants, energy changes, and the role of catalysts. Perfect for students studying chemistry concepts related to reactions and their conditions.

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