Chapter 3: Airbags - Chemistry Making Car Rides Safer

Vocabulary flashcards derived from Chapter 3 text covering states of matter, physical and chemical properties and changes, density, and kinetic molecular theory.

Airbag Chemical Reaction

The decomposition reaction $2\text{NaN}_3(s) \rightarrow 2\text{Na}(s) + 3\text{N}_2(g)$ that occurs in $\frac{1}{25}$ of a second to rapidly inflate an airbag with gas.

Sodium Azide ($\text{NaN}_3$)

A highly toxic solid chemical reactant used in airbags that rapidly decomposes into sodium metal and nitrogen gas when electrically ignited.

Solid

A state of matter consisting of closely packed particles vibrating in place, characterized by non-compressibility, a definite shape, and a definite volume.

Liquid

A state of matter where particles have higher energy than a solid and flow freely around each other, characterized by negligible compressibility, no definite shape, and a definite volume.

Gas

A state of matter in which high-energy particles move randomly and rapidly far apart from one another, resulting in high compressibility and no definite shape or volume.

Sublimation

The phase change in which a solid transitions directly into a gas without becoming a liquid.

Deposition

The phase change in which a gas transitions directly into a solid without becoming a liquid.

Physical Property

A characteristic of matter that can be observed or measured without altering the chemical composition of the substance, such as color, texture, density, or melting point.

Chemical Property

A characteristic describing how a substance reacts with other chemicals or elements, resulting in a change to its original chemical structure.

Intensive Property

A property of a substance that remains the same regardless of the sample size, such as color, density, or melting point.

Extensive Property

A property of a substance that changes depending on the size or quantity of the sample, such as mass or volume.

Density

An intensive physical property defined as the mass per unit volume of an object, commonly measured in units of $\text{g/mL}$ or $\text{g/cm}^3$.

Physical Change

A change affecting only the physical properties of a sample without altering its chemical structure, such as changes of state or dissolving.

Chemical Change

A process that rearranges atoms or molecules to create new substances with distinct chemical and physical properties.

Pressure

The force exerted by gas atoms or molecules colliding with the walls of their container.

Atmospheric Pressure

The pressure exerted by the weight of atmospheric air layers pushing down, which decreases as altitude increases.

Kinetic Molecular Theory (KMT)

A theoretical model describing gas behavior based on assumptions about particle mass, continuous random motion, elastic collisions, and kinetic energy proportional to temperature.

Diffusion

The rate or speed at which gas particles move across a space, which is inversely related to particle size and mass.

Effusion

The rate or speed at which gas particles escape through a tiny opening in a container, which is inversely related to particle size and mass.

Avogadro's Number

The constant value $6.02 \times 10^{23}$, representing the total number of particles present in one mole of a substance.