Questions and Answers
What type of reaction involves the combination of two or more substances to form a new substance?
What is the purpose of a chemical equation?
Which of the following factors does NOT affect the rate of a chemical reaction?
Which type of reaction absorbs heat energy?
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What is the role of a catalyst in a chemical reaction?
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What is the term for a reaction in which one substance loses electrons and another substance gains electrons?
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Which type of chemical reaction involves the breakdown of a single substance into two or more substances?
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What is the term for the substances that undergo a chemical change?
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What is the principle that states that matter cannot be created or destroyed in a chemical reaction?
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Which of the following factors can increase the rate of a chemical reaction?
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What is the term for the ratio of the number of moles of reactants to the number of moles of products?
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Which type of chemical reaction involves the exchange of partners between two compounds?
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What is the term for a formula that shows the simplest whole-number ratio of atoms of each element in a compound?
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Which of the following is NOT a characteristic of a chemical reaction?
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Study Notes
Chemical Reactions
Chemical Equation
- A chemical equation is a symbolic representation of a chemical reaction
- It represents the reactants, products, and their respective quantities
- The reactants are written on the left-hand side, and the products are written on the right-hand side
- The arrow (→) is used to separate the reactants from the products
Types of Chemical Reactions
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Combination Reaction: A reaction in which two or more substances combine to form a new substance
- Example: 2H2 + O2 → 2H2O
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Decomposition Reaction: A reaction in which a single substance breaks down into two or more substances
- Example: 2H2O → 2H2 + O2
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Displacement Reaction: A reaction in which one element displaces another element from a compound
- Example: Zn + CuSO4 → ZnSO4 + Cu
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Oxidation and Reduction: A reaction in which one substance loses electrons (oxidation) and another substance gains electrons (reduction)
- Example: 2CuO + H2 → 2Cu + H2O (CuO is reduced, H2 is oxidized)
Chemical Reaction Rates
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Factors Affecting Reaction Rates:
- Concentration of reactants
- Temperature
- Surface area of reactants
- Presence of catalysts
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Catalysts: Substances that increase reaction rates without being consumed by the reaction
- Examples: enzymes, vanadium(V) oxide (V2O5)
Exothermic and Endothermic Reactions
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Exothermic Reaction: A reaction that releases heat energy
- Example: combustion of fuels
-
Endothermic Reaction: A reaction that absorbs heat energy
- Example: photosynthesis in plants
Chemical Reactions
Chemical Equation
- A chemical equation represents reactants, products, and their quantities
- Reactants are on the left, products on the right, separated by an arrow (→)
Types of Chemical Reactions
- Combination Reaction: two or more substances combine to form a new substance (2H2 + O2 → 2H2O)
- Decomposition Reaction: a single substance breaks down into two or more substances (2H2O → 2H2 + O2)
- Displacement Reaction: one element displaces another from a compound (Zn + CuSO4 → ZnSO4 + Cu)
- Oxidation and Reduction: one substance loses electrons (oxidation) and another gains electrons (reduction) (2CuO + H2 → 2Cu + H2O)
Chemical Reaction Rates
-
Factors Affecting Reaction Rates:
- Concentration of reactants
- Temperature
- Surface area of reactants
- Presence of catalysts
- Catalysts: substances that increase reaction rates without being consumed (enzymes, vanadium(V) oxide (V2O5))
Exothermic and Endothermic Reactions
- Exothermic Reaction: releases heat energy (combustion of fuels)
- Endothermic Reaction: absorbs heat energy (photosynthesis in plants)
Chemical Reactions
Types of Chemical Reactions
- A combination reaction occurs when two or more substances combine to form a new substance, such as 2H2 + O2 → 2H2O.
- In a decomposition reaction, a single substance breaks down into two or more substances, such as 2H2O → 2H2 + O2.
- A displacement reaction involves one element displacing another element from a compound, such as Zn + CuSO4 → ZnSO4 + Cu.
- In a double displacement reaction, two compounds exchange partners, resulting in the formation of two new compounds, such as NaCl + AgNO3 → NaNO3 + AgCl.
- Oxidation-reduction reactions involve the gain or loss of electrons, such as 2Mg + O2 → 2MgO, where Mg loses electrons and O2 gains electrons.
Characteristics of Chemical Reactions
- Reactants are the substances that undergo a chemical change.
- Products are the substances formed as a result of a chemical change.
- A chemical equation is a representation of a chemical reaction using chemical formulas and symbols.
- The Law of Conservation of Mass states that matter cannot be created or destroyed in a chemical reaction.
Factors Affecting Chemical Reactions
- Increasing the concentration of reactants can increase the rate of reaction.
- Higher temperatures can increase the rate of reaction.
- A catalyst is a substance that speeds up a chemical reaction without being consumed.
- Increasing the surface area of reactants can increase the rate of reaction.
Stoichiometry
- The mole ratio is the ratio of the number of moles of reactants to the number of moles of products.
- A mole formula shows the number of moles of each element in a compound.
- The empirical formula shows the simplest whole-number ratio of atoms of each element in a compound.
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Description
Learn about chemical equations, reactants, products, and types of chemical reactions such as combination reactions.
