Chemistry Chapter 7 Vocabulary

Chemical Reactions Key Terms

• Reactants: Substances that undergo change in a chemical reaction.
• Products: Substances formed as a result of a chemical change.

Chemical Equations

• Chemical Equation: Represents a chemical reaction with reactants and products expressed as formulas.
• Law of Conservation of Mass: Mass is neither created nor destroyed during a chemical reaction.
• Balancing Equations: To demonstrate mass conservation, a chemical equation must be balanced.
• Coefficients: Numbers that precede formulas used to balance chemical equations.

Moles and Molar Mass

• Mole: An amount of substance containing approximately (6.022 \times 10^{23}) particles, known as Avogadro's number.
• Molar Mass: The mass of one mole of a substance, equivalent to the element's atomic mass in grams or the sum of atomic masses for compounds.

Calculating Masses

• Calculating Mass: The mass of reactants or products can be calculated using a balanced equation and molar masses.

Types of Chemical Reactions

• General Types: Synthesis, decomposition, single-replacement, double-replacement, combustion, and redox reactions.

Specific Reaction Types

• Synthesis Reaction: Two or more substances combine to form one compound; reactants can be elements or compounds.
• Decomposition Reaction: A compound breaks down into two or more simpler substances.
• Single-Replacement Reaction: One element replaces another in a compound.
• Double-Replacement Reaction: Two different compounds exchange positive ions to form new compounds.
• Combustion Reaction: Rapid reaction with oxygen producing heat and light.
• Redox (Oxidation-Reduction) Reaction: Involves the transfer of electrons between reactants.

Oxidation and Reduction

• OIL RIG: Mnemonic for Oxidation Is Loss, Reduction Is Gain.
• Oxidation: Occurs when a metal combines with oxygen.
• Reduction: Involves an atom gaining electrons.

Energy in Chemical Reactions

• Chemical Energy: Energy stored in chemical bonds of substances.
• Energy Changes: Reactions may absorb or release energy.
• Exothermic Reaction: Releases energy, heating surroundings; energy released surpasses energy needed to break reactants' bonds.
• Endothermic Reaction: Absorbs energy; energy required to break bonds exceeds energy released in formation of products.
• Law of Conservation of Energy: Total energy remains constant before and after a reaction, applicable in both exothermic and endothermic processes.

Reaction Rates

• Reaction Rate: Speed at which reactants convert to products; indicates how fast a reaction occurs.
• Factors Affecting Reaction Rates: Temperature, surface area, concentration, stirring, and presence of catalysts.
• Temperature: Increased temperature speeds up particles, leading to more frequent collisions.
• Surface Area: Smaller particles have a larger surface area, allowing more collisions.
• Stirring: Enhances substrate exposure and increases collision frequency.
• Concentration: Higher concentration provides more reactant particles, accelerating the reaction.
• Catalyst: Increases reaction rates without being consumed; may lower temperature requirements for reactions.

Equilibrium Concepts

• Equilibrium: Occurs when forward and reverse reactions happen at the same rate.
• Physical Equilibrium: Established when physical changes do not go to completion.
• Chemical Equilibrium: Occurs when chemical reactions do not go to completion.
• Reversible Reactions: Allow simultaneous conversion of reactants to products and vice versa.