Chemical Reactions Lecture Flashcards

Vocabulary-style flashcards covering the concepts, equations, and classifications of various chemical reactions from the lecture notes.

Chemical Change

A process where chemical bonds are broken and reform in new combinations to create new products, such as combustion, rotting, rusting, or digestion.

Physical Change

A process where matter changes form but not its chemical composition, such as melting ice, shredding paper, boiling water, or chopping wood.

Law of Conservation of Mass

Established by Antoine Lavoisier in the 1700s, it states that matter is neither created nor destroyed during a chemical reaction, meaning the total mass of reactants equals the total mass of products.

Closed System

A reaction environment where no matter enters or escapes, often used to demonstrate the Law of Conservation of Mass.

Open System

A reaction environment where gases or other matter can escape into the atmosphere, which may cause an apparent change in measured mass.

Subscripts

Small numbers at the bottom right of a chemical symbol that define the internal molecular composition; they must never be altered when balancing equations.

Coefficients

Large numbers placed in front of a chemical formula that multiply the entire molecule and are adjusted to balance chemical equations.

Synthesis Reaction

A reaction where two or more simple substances combine to form a single, more complex product, generally following the formula $A + B \rightarrow AB$.

Polymers

Large molecules made by joining thousands of smaller units called monomers in a long chain, such as polyethylene.

Corrosion

The gradual destruction of a metal due to a chemical reaction with its environment, which is technically a synthesis reaction where a metal combines with oxygen gas to form a metal oxide.

Rusting

A specific type of corrosion that only applies to Iron ($Fe$) and its alloys, forming Iron (III) oxide ($Fe_2O_3$).

Galvanising

A corrosion prevention method where iron structural surfaces are coated with a sacrificial Zinc ($Zn$) layer.

Decomposition Reaction

A reaction where a single complex compound breaks down into two or more simpler substances, following the formula $AB \rightarrow A + B$.

Thermal Decomposition

A type of decomposition reaction that uses heat energy to break chemical bonds, such as heating copper carbonate ($CuCO_3$).

Photo Decomposition

A type of decomposition reaction that uses light energy to break chemical bonds, such as silver chloride ($AgCl$) reacting in sunlight.

Electrolytic Decomposition

A type of decomposition reaction that uses electricity to force a reaction, such as the electrolysis of water ($H_2O$).

Catalyst

A substance that speeds up a chemical reaction without being consumed, such as potassium iodide ($KI$) in the decomposition of hydrogen peroxide.

Single Displacement Reaction

A redox process occurring when a more reactive solid metal transfers electrons to the aqueous ions of a less reactive metal, following the formula $A + BC \rightarrow AC + B$.

Activity Series

A ranking of metals from most reactive (Potassium) to least reactive (Gold) used to predict if a displacement reaction will occur spontaneously.

Sacrificial Anode

A more reactive metal (like Zinc) used to protect industrial steel infrastructure by corroding first to preserve the iron's structural integrity.

Precipitation Reaction

Also known as a double displacement reaction, it occurs when two aqueous ionic solutions are mixed and swap ion partners to form a solid precipitate ($AB(aq) + CD(aq) \rightarrow AD(s) + CB(aq)$).

Precipitate

An insoluble solid that forms when two aqueous solutions are mixed, often indicated by cloudiness, turbidity, or the formation of visible grains.

Solubility Guidelines

A set of rules used to predict which product of a double displacement reaction will be a solid ($s$) and which will remain aqueous ($aq$).

Acids

Substances that release Hydrogen ions ($H^+$) in water, typically have a sour taste, a pH range of $0$ to $6.9$, and turn Universal Indicator red or orange.

Bases

Substances that release Hydroxide ions ($OH^-$) in water, feel slippery or soapy, have a pH range of $7.1$ to $14$, and turn Universal Indicator blue or purple.

Alkalis

A term used specifically for bases that are soluble in water.

pH Scale

A scale ranging from $0$ to $14$ used to relate the concentration of Hydrogen ($H^+$) and Hydroxide ($OH^-$) ions, where $7$ is neutral.

Digital pH Probe

An instrument that measures the tiny voltage difference between a glass membrane sensitive to Hydrogen ions ($H^+$) and a reference electrode.

Metal-Acid Reaction

A reaction following the general formula $Metal + Acid \rightarrow Salt + Hydrogen\,Gas$.

The Pop Test

A chemical test used to confirm the presence of Hydrogen gas ($H_2$) by igniting it with a wooden splint to produce a characteristic sound.