Lecture 2: Properties of Matter (Che131)

Flashcards covering key concepts from the lecture notes on matter properties, including chemical vs physical properties, intensive vs extensive properties, states and phase changes, density, and phase diagrams.

What is chemistry the science of?

Matter—its composition, structure, and properties; measurements involve the changes matter undergoes and the energy associated with these changes.

What is matter?

Matter makes up all substances; consists of molecules, atoms, and sub-atomic particles; occupies space, has mass, and experiences gravity.

What is a chemical property?

A property observed only when matter reacts with another substance (e.g., hydrogen reacting explosively with oxygen).

What is a physical property?

A property observed without changing the substance (e.g., density, hardness, color).

What is an intensive property?

Independent of the amount of substance present (e.g., color, boiling point, melting point, conductivity, hardness, malleability, ductility, specific gravity, magnetism, concentration).

What is an extensive property?

Depends on the amount of substance present (e.g., length, width, mass, volume, energy, enthalpy, entropy).

Why is density considered an intensive property?

Because density is the ratio of two extensive quantities (mass and volume) that scale the same way, so it does not depend on the amount of substance.

What are the three states of matter and their characteristics?

Solids have definite shape and volume; liquids have definite volume but not shape; gases have neither definite shape nor volume.

What are common phase changes?

Melting, Freezing, Deposition, Vaporization, Condensation, Sublimation.

What energy changes accompany phase changes?

Energy changes occur in the system; energy is absorbed or released as matter changes phase.

What does a phase diagram show?

The different phases of a substance as a function of temperature and pressure (T and P).

What does the phase diagram for H2O illustrate?

Phase relationships between ice, liquid water, and water vapor for water across different temperatures and pressures.

What is the formula for density?

Density = mass/volume (D = M/V).

If a liquid has density 0.87 g/mL and mass 25 g, what is its volume?

Volume = mass/density = 25 g / 0.87 g/mL ≈ 28.7 mL (about 29 mL).

What is the relationship between two extensive quantities that makes density an intensive property?

The ratio of two extensive quantities that scale in the same way is scale-invariant, hence intensive.

Which property is illustrated by the Hindenburg disaster (reactivity)?

Chemical property—reactivity leading to combustion.