Comprehensive Introductory Chemistry: Measurement, Density, Units, and Thermochemistry Vocabulary

Flashcards covering fundamental vocabulary from Introductory Chemistry notes on scientific method, measurements, density, significant figures, energy, and thermochemistry.

Chemistry

The science that deals with the materials of the universe and the changes that these materials undergo.

Scientific Method

A systematic process lying at the center of scientific inquiry for gaining, organizing, and processing knowledge.

Hypothesis

A possible explanation for an observation.

Theory (Model)

A set of tested hypotheses that gives an overall explanation of some natural phenomenon by attempting to explain why it happens.

Natural Law

A summary of observed measurable behavior that describes what happens in nature.

Accuracy

Refers to how close a measurement is to the theoretical or true value for the property being measured.

Precision

Refers to the reproducibility of a measurement, or how close repeated measurements are to one another.

Uncertain Digit

The estimated digit recorded as the final digit in a measurement.

Leading Zeros

Zeros that precede all of the nonzero digits in a number; they never count as significant figures.

Captive Zeros

Zeros that fall between nonzero digits in a number; they always count as significant figures.

Trailing Zeros

Zeros at the right end of a number; they are significant only if the number contains a decimal point.

Exact Numbers

Numbers determined by counting or defined unit conversions that possess an unlimited number of significant figures.

Mass

A measure of the amount of matter present in an object, having the fundamental SI unit of kilogram ($\text{kg}$).

Volume

A measure of the amount of three-dimensional space occupied by a substance, having the SI unit of cubic meter ($\text{m}^3$).

Density

The mass of a substance per unit volume of the substance, expressed by the formula $D = \frac{m}{v}$.

Water Displacement

A method used to measure the volume of a solid object by observing the volume of water it displaces when submerged.

Percent Error

A standard measurement of experimental accuracy calculated using the formula $\% \text{ error} = \frac{|T - E|}{T} \times 100$, where $T$ is the theoretical value and $E$ is the experimental value.

Energy

The ability to do work or produce heat, or that which is needed to oppose natural attractions.

Law of Conservation of Energy

The law stating that energy can be converted from one form to another but can be neither created nor destroyed, maintaining a constant total energy content in the universe.

Potential Energy

Energy due to the position or composition of an object.

Kinetic Energy

Energy due to the motion of an object, which depends on the mass of the object and its velocity.

Temperature

A measure of the random motions of the components of a substance.

Heat

A flow of energy between two objects due to a temperature difference between them.

System

The specific part of the universe on which attention is focused during an observation or experiment.

Surroundings

Everything in the universe outside of the defined system.

Exothermic Process

A process in which energy flows out of the system into the surroundings, resulting in products with lower potential energy than the reactants.

Endothermic Process

A process in which heat flows into a system from the surroundings, increasing the potential energy of the system.

calorie (cal)

The amount of energy required to raise the temperature of one gram of water by $1^\circ\text{C}$.

Joule (J)

The SI unit of energy, defined by the conversion rate $1\,\text{calorie} = 4.184\,\text{joules}$.

Calorie (dietary)

The dietary unit of energy, equal to $1000\,\text{calories}$ or $1\,\text{kilocalorie}$.

Specific Heat Capacity

The energy required to change the temperature of one gram of a substance by one Celsius degree ($1^\circ\text{C}$).

Calorimetry

The technique of measuring heat flow and changes in enthalpy ($H$) during chemical or physical reactions using a calorimeter.