States, Classification of Matter, Energy, and Combustion Chemistry

Vocabulary practice flashcards covering states of matter, units, scientific reasoning, energy conversion, thermodynamics, fuels, and chemistry of combustion.

Macroscopic Perspective

The level of chemistry focusing on what can be seen and measured directly.

Microscopic Perspective

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

Symbolic Perspective

The shorthand representation used in chemistry, such as the Periodic Table, Chemical Formulas, and Equations.

Solid

A state of matter with a definite shape and volume that is not compressible, whose particles vibrate in place due to strong forces.

Liquid

A state of matter with a definite volume that takes the shape of its container and is not compressible, whose particles move freely enough to slide past each other.

Gas

A state of matter with no fixed shape or volume that fills its container and is highly compressible, whose particles are far apart and move independently.

Plasma

An electrically conductive state of matter with no fixed shape or volume that responds to magnetic fields and occurs at extremely high temperatures where particles become charged.

Intensive Properties

Physical properties that do NOT depend on the amount of matter present, such as density, color, boiling point, and hardness.

Extensive Properties

Physical properties that DO depend on the amount of matter present, such as mass, volume, and weight.

Chemical Properties

Characteristics observed only when a substance changes into something new, such as reactivity, flammability, toxicity, and ability to oxidize.

Pure Substances

Matter with a fixed composition that cannot be separated by physical means, consisting of elements or compounds.

Elements

Pure substances made of only one kind of atom, such as Oxygen or Iron.

Compounds

Pure substances made of two or more kinds of atoms bonded together, such as Water or Salt.

Homogeneous Mixture

A mixture with a uniform composition throughout, such as solutions like saltwater.

Heterogeneous Mixture

A mixture with a non-uniform composition where different constituent parts can be visually distinguished, such as sand and water.

Acid

A substance that donates $\text{H}^+$ ions in water.

Base

A substance that accepts $\text{H}^+$ ions or produces $\text{OH}^-$ ions in water.

Salt

An ionic compound formed from the reaction between an acid and a base.

Organic Compounds

Carbon-containing compounds, with exceptions such as carbonates and $\text{CO}_2$.

Operational Definition

A physical quantity defined by describing how to measure it, such as defining a meter by the distance light travels in a specific fraction of a second.

Mole

The SI base unit for amount of substance ($\text{mol}$), representing a count of particles equal to $6.022 \times 10^{23}$ (Avogadro's number).

Dimensional Analysis

A technique, also known as the Factor-Label Method, that uses conversion factors in fraction form to cancel unwanted units and isolate desired ones.

Principle of Homogeneity

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

Scientific Observation

Any data recorded during an experiment by receiving knowledge through the senses or by 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 variability occurring due to chance and caused by different unpredictable sources of error.

Systematic Error

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

Accuracy

How close an observed measurement value is to the true or accepted value.

Absolute Error

The difference obtained by subtracting the accepted value from the experimental value ($\text{Experimental value} - \text{Accepted value}$).

Percent Relative Error

A measure of accuracy calculated as $\left[\frac{\text{Experimental value} - \text{Accepted value}}{\text{Accepted value}}\right] \times 100$.

Precision

The degree of agreement or spread among repeated values obtained from measurements.

Scientific Law

A statement that generalizes a quantity of experimentally observable phenomena, such as the Law of Conservation of Mass.

Hypothesis

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

Theory

A logical model accepted based on experimental verification of hypotheses, such as Atomic Theory or Kinetic Molecular Theory.

Inductive Reasoning

A bottom-up, data-driven reasoning process that proceeds from specific observations to pattern recognition to a general conclusion.

Deductive Reasoning

A top-down, theory-driven reasoning process that starts with an existing theory or hypothesis and tests specific possibilities to reach a logical conclusion.

Kinetic Energy

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

Potential Energy

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

Efficiency

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

System

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

Surroundings

Everything outside the thermodynamic system being studied.

Open System

A thermodynamic system across whose boundary both mass and energy can flow.

Closed System

A thermodynamic system across whose boundary energy can pass, but mass cannot.

Isolated System

A theoretical thermodynamic system across whose boundary neither mass nor energy can pass.

Internal Energy

The total energy stored inside a system ($\Delta U$), equal to the sum of all kinetic and potential energies of its particles.

First Law of Thermodynamics

The principle stating that energy cannot be created or destroyed—it can only change forms, making the total energy of the universe constant.

Lignite

Soft, brown low-grade coal containing $65\text{--}70\%$ carbon.

Subbituminous Coal

Grey-black, medium-grade coal containing $70\text{--}76\%$ carbon.

Bituminous Coal

Dull black, high-grade soft coal containing $76\text{--}86\%$ carbon.

Anthracite

Hard, brittle, lustrous black coal representing the highest grade with $86\text{--}92\%$ carbon.

Ultimate Analysis

An elemental analysis quantifying the elemental composition (C, H, O, N, S, ash) of coal for chemical calculations.

Proximate Analysis

An analysis of coal quantifying its compound composition and heat value (moisture, volatile matter, sulfur, ash) for power generation.

Ignition Temperature

The minimum temperature required to initiate self-sustaining combustion of a fuel.

Flash Point

The lowest temperature at which fuel vapor briefly ignites in the presence of an ignition source.

Fire Point

The lowest temperature at which fuel vapor continues burning for at least 5 seconds.

Octane Rating

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

Alkanes

Aliphatic hydrocarbons containing only single carbon-carbon bonds ($\text{C--C}$) with general formula $\text{C}_n\text{H}_{2n+2}$.

Alkenes

Aliphatic hydrocarbons containing at least one double carbon-carbon bond ($\text{C=C}$) with general formula $\text{C}_n\text{H}_{2n}$.

Alkynes

Aliphatic hydrocarbons containing at least one triple carbon-carbon bond ($\text{C}\equiv\text{C}$) with general formula $\text{C}_n\text{H}_{2n-2}$.

Complete Combustion

A reaction occurring in plentiful oxygen where a fuel reacts to produce $\text{CO}_2$ and $\text{H}_2\text{O}$.

Incomplete Combustion

A reaction occurring under limited oxygen that produces $\text{CO}$ (carbon monoxide), $\text{C}$ (soot), $\text{CO}_2$, and $\text{H}_2\text{O}$.

Higher Heating Value (HHV)

The combustion energy calculated assuming the water product is in liquid form ($\text{H}_2\text{O}_{(l)}$), which includes the heat of vaporization.

Lower Heating Value (LHV)

The combustion energy calculated assuming the water product is in vapor form ($\text{H}_2\text{O}_{(g)}$), which excludes the heat of vaporization.