Chemistry Chapter 8 Flashcards

Chemical Reactions

• A chemical reaction transforms one or more substances into different substances with distinct physical and chemical properties, indicating a change of identity.

Indications of a Chemical Reaction

• Evolution of energy as heat or light may occur.
• Production of gas, evidenced by smoke or bubbles, without heat.
• Formation of a precipitate, a solid generated from mixing two solutions.
• Observable color change.

Diatomic Elements

• Diatomic elements include H₂, N₂, O₂, F₂, Cl₂, Br₂, I₂, forming a "7" on the periodic table.
• In chemical equations, represent diatomic elements with subscripts only when alone.

Chemical Equation

• Represents reactants and products using symbols and formulas, detailing their identities and relative amounts.

Characteristics of a Chemical Equation

• Must accurately represent known facts, including states of matter.
• Requires correct chemical formulas for all reactants and products.
• Must comply with the Law of Conservation of Mass, meaning mass cannot be created or destroyed.

Steps to Write a Chemical Equation

• Begin with a word equation denoting reactants and products.
• Convert the word equation into a formula equation including states of matter.
• Balance the equation to ensure conservation of mass.

Symbols in a Chemical Equation

• An arrow signifies "yields."
• A downward arrow indicates a precipitate formation.
• An upward arrow denotes a gas as a product.
• A delta or triangle symbolizes heat application.
• Numbers above the arrow represent reaction pressure (atm) and temperature (°C).
• A catalyst is denoted by additional formulas above the arrow.

Balancing Chemical Equations

• Conservation of mass requires that the total number of atoms at the beginning equals those at the end of a reaction.
• Balance elements last when they appear in multiple compounds or alone on one side.
• Treat polyatomic ions as single units during balancing.
• Rewrite water as HOH when hydroxide ions are on one side of the equation and water on the other.
• Check chemical formulas for accuracy if balancing is difficult.

Types of Reactions

• Synthesis Reaction: Two or more substances combine to form a new compound (e.g., A + X → AX).
• Decomposition Reaction: A single compound breaks down into simpler substances (e.g., AX → A + X).

Types of Synthesis and Decomposition Reactions

• Synthesis examples include metal + oxygen forming metal oxide, and nonmetal oxide + water producing acid.
• Decomposition examples comprise metal carbonate yielding metal oxide and carbon dioxide.

Single Displacement Reaction

• Involves one element replacing a similar element in a compound (e.g., A + BX → AX + B).
• Metal replacement occurs when a metal displaces another in a compound; hydrogen can also be replaced by metals.
• Nonmetal displacement occurs similarly among nonmetals.

Double Displacement Reaction

• Involves ions of two compounds exchanging places to form new compounds (e.g., AX + BY → AY + BX).
• Common products include precipitate, gas, or water.

Combustion Reaction

• A hydrocarbon reacts with oxygen to produce carbon dioxide and water (e.g., CₓHᵧ(O𝓏) + O₂ → CO₂ + H₂O).
• These reactions release significant energy as light and heat.

Other Key Concepts

• A precipitate is a solid formed from the reaction of two liquids.
• Coefficients indicate the number of moles present in a reaction.
• Reversible reactions allow switching between reactants and products.
• Electrolysis involves using electricity to drive a chemical reaction, often leading to the decomposition of compounds like water.

Test your knowledge of chemical reactions with these flashcards from Chemistry Chapter 8. Learn key terms and their definitions, including indications of a chemical reaction. Perfect for reviewing before an exam or enhancing your understanding of the subject.