States, Classification of Matter, Energy, and Combustion

Vocabulary practice flashcards covering fundamental chemistry topics including states of matter, physical quantities, thermodynamic laws, precision, energy forms, fuel types, and combustion chemistry.

Macroscopic Perspective

The viewpoint of chemistry focused on what can be seen and measured directly.

Microscopic Perspective

The viewpoint of chemistry focused on invisible particles (atoms and molecules) that make up matter.

Symbolic Perspective

The shorthand representation used in chemistry, including the Periodic Table, chemical formulas, and equations.

Matter

Anything that has mass and takes up space.

Physical Properties

Properties of matter that are measured without changing the substance's identity.

Intensive Properties

Physical properties that do NOT depend on the amount of substance present (e.g., density, color, boiling point, hardness).

Extensive Properties

Physical properties that DO depend on the amount of substance present (e.g., mass, volume, weight).

Chemical Properties

Properties observed only when a substance changes into something new (e.g., reactivity, flammability, toxicity, ability to oxidize).

Pure Substances

Matter with a fixed composition that cannot be separated by physical means.

Elements

Pure substances made of only one kind of atom (e.g., Oxygen, Iron).

Compounds

Pure substances made of two or more kinds of atoms bonded together (e.g., Water, Salt).

Mixtures

Matter with variable composition where each part keeps its own identity and can be separated physically.

Homogeneous Mixture

A mixture with uniform composition throughout (e.g., solutions like saltwater).

Heterogeneous Mixture

A non-uniform mixture in which different parts can be seen (e.g., sand and water).

Acids

Substances that donate $H^+$ ions in water.

Bases

Substances that accept $H^+$ ions (or produce $OH^-$ ions in water).

Salts

Ionic compounds formed from an acid and a base.

Organic Compounds

Carbon-containing compounds, with exceptions like carbonates and $CO_2$.

Inorganic Compounds

Compounds that typically do not contain carbon.

Operational Definition

A physical quantity defined by describing how to measure it.

System

The specific matter or region of space being studied in thermodynamics.

Surroundings

Everything outside the thermodynamic system.

Boundary

The imaginary closed surface that separates the system from the surroundings.

Open System

A system where both mass and energy can cross the boundary.

Closed System

A system where energy can cross the boundary, but mass cannot.

Isolated System

A system where neither mass nor energy can cross the boundary.

Internal Energy (\Delta U)

The total energy stored inside a system, equal to the sum of all kinetic and potential energies of its particles.

Heat (Q)

Energy that flows spontaneously between two objects due to a temperature difference.

Work (W)

Energy transferred between a system and its surroundings through macroscopic forces.

Scientific Notation

A shorthand for very large or very small numbers formatted as $\text{Coefficient} \times 10^{\text{Exponent}}$.

Dimensional Analysis

A technique (Factor-Label Method) that uses conversion factors (fractions) to cancel unwanted units and leave desired ones.

Principle of Homogeneity

The principle stating that the dimensions on both sides of an equation must match.

Scientific Observation

Any data recorded during an experiment, acquired by receiving knowledge through senses or using scientific instruments.

Scientific Uncertainty

A range of possible values within which the true value of a measurement lies, representing the degree of probable error.

Random Error

Measurement error occurring due to chance and variability when a measurement is made.

Systematic Error

Measurement error due to identified causes that can be eliminated in principle, resulting in values consistently too high or consistently too low.

Accuracy

How close the observed value is to the "true" value.

Precision

The spread in values obtained from repeated measurements.

Scientific Law

A statement that generalizes a quantity of experimentally observable phenomena.

Hypothesis

A generalization that attempts to explain why certain experimental results occur.

Theory/Model

A general explanation that is formed when a hypothesis is accepted based on experiment.

Inductive Reasoning

A bottom-up logic approach moving from specific observations to pattern recognition to a general conclusion.

Deductive Reasoning

A top-down logic approach starting with an existing theory to formulate hypotheses, collect and analyze data, and reach conclusions.

Kinetic Energy (KE)

The energy of motion, depending on an object's speed and mass.

Potential Energy (PE)

The energy of position or storage, depending on an object's location or internal structure.

Efficiency

A cost-benefit ratio measuring performance calculated as $\text{Efficiency (\%)} = \left(\frac{\text{Useful Energy Output}}{\text{Energy Input}}\right) \times 100$.

Higher Heating Value (HHV)

The calculated heat value assuming the water product is in liquid form ($H_2O_{(l)}$), including the heat of vaporization.

Lower Heating Value (LHV)

The calculated heat value assuming the water product is in vapor form ($H_2O_{(g)}$), excluding the heat of vaporization.

Non-Renewable Energy

Energy resources that will run out or will not be replenished in our lifetimes, mined or extracted from the Earth.

Renewable Energy

Energy resources that are virtually inexhaustible in duration (though limited in rate per unit time) and naturally replenished.

Primary Fuels

Natural, unconverted fuels (e.g., wood, coal, crude oil, natural gas).

Secondary Fuels

Artificial fuels converted from primary resources (e.g., charcoal, gasoline, diesel, hydrogen).

Ultimate/Elemental Analysis

Analysis of coal that quantifies its elemental composition ($C$, $H$, $O$, $N$, $S$, ash) for chemistry.

Proximate Analysis

Analysis of coal that quantifies compounds and heat value (moisture, volatile matter, sulfur, ash) for power generation.

Ignition Temperature

The minimum temperature required for self-sustaining combustion.

Flash Point

The lowest temperature where fuel vapor briefly ignites.

Fire Point

The lowest temperature where fuel vapor continues burning for $\ge 5\,\text{seconds}$.

Smoke Point

The temperature at which a fuel starts to smoke.

Octane Rating

A measurement of gasoline's resistance to knocking (premature combustion), based on the ratio of isooctane to n-heptane.

Complete Combustion

A combustion reaction with plenty of oxygen that produces $CO_2 + H_2O$.

Incomplete Combustion

A combustion reaction with limited oxygen that produces $CO$ (carbon monoxide) + $C$ (soot) + $CO_2 + H_2O$.

Mole (mol)

A count of particles equal to $6.022 \times 10^{23}$ (Avogadro's number).

Formula Weight (Molar Mass)

The mass of $1\,\text{mole}$ of a substance ($\text{g\,mol}^{-1}$), calculated as the sum of atomic weights from the periodic table.

Empirical Formula

The simplest whole-number ratio of atoms in a compound.

Molecular Formula

The actual number of atoms in a molecule.

Sigma (\sigma) Bonds

Strong covalent chemical bonds formed by head-on overlap of atomic orbitals.

Pi (\pi) Bonds

Covalent chemical bonds formed by sideways overlap of atomic orbitals in double or triple bonds.

Octet Rule

The rule stating that atoms tend to gain, lose, or share electrons to reach 8 valence electrons.

Alkanes (Paraffins)

Hydrocarbons containing only single bonds ($C-C$) with the general formula $C_n H_{2n+2}$.

Alkenes (Olefins)

Hydrocarbons containing at least one double bond ($C=C$) with the general formula $C_n H_{2n}$.

Alkynes (Acetylenes)

Hydrocarbons containing at least one triple bond ($C\equiv C$) with the general formula $C_n H_{2n-2}$.

Aromatic Hydrocarbons

Hydrocarbons derived from benzene ($C_6 H_6$) featuring ring structures with pleasant smells.