PHS 1000L - LAB 02: States of Matter, Chemical Formulae and Physio-chemical Properties

A set of Q&A style flashcards covering states of matter, mixtures, solutions, physical and chemical properties, density, and evaporation factors based on the lecture notes.

What are the three states of matter?

Solid, liquid, and gas.

Describe a solid's particle arrangement and its fixed properties.

Particles are close together, often in a crystalline arrangement; solids have fixed volume and fixed shape.

Describe a liquid's shape and volume.

A liquid has a definite volume but takes the shape of its container.

Describe a gas's shape and volume.

A gas has no definite shape or volume and expands to fill its container.

How is matter classified by composition?

As either a pure substance or a mixture.

What is a pure substance?

A substance with only one component; examples include elements and compounds (e.g., water, H2O).

What is a mixture?

A combination of two or more pure substances in which each substance retains its own identity; can be homogeneous or heterogeneous.

What is a homogeneous mixture?

Uniform composition; well-mixed; a solution (e.g., alcohol in water; air as a gaseous solution).

What is a heterogeneous mixture?

Non-uniform composition; examples include salt and pepper; concrete.

Is seawater a pure substance, a homogeneous mixture, or a heterogeneous mixture?

A heterogeneous mixture.

What is an aqueous solution?

A solution where a solute is dissolved in water (e.g., vinegar, NaCl in water, NaHCO3 in water).

In Practice Problem 1, what is the classification of ethanol?

Pure substance.

In Practice Problem 1, what is the classification of an Alka-Seltzer tablet fizzing in water?

Heterogeneous mixture.

In Practice Problem 1, what is the classification of blood?

Heterogeneous mixture.

In Practice Problem 1, what is the classification of oxygen from a hospital oxygen tank?

Pure substance.

What is a physical change?

A change in appearance without changing the chemical composition (identity) of a substance.

What are melting point and boiling point?

Melting point is the temperature at which a solid becomes a liquid; boiling point is the temperature at which a liquid becomes a gas; both are physical properties.

What is density?

Mass per unit volume; density = mass/volume (units g/mL or g/cm^3).

What is specific gravity?

The ratio of a substance's density to the density of water (1.00 g/mL at 4°C); unitless.

How do you determine the density of a liquid experimentally?

Weigh a container with a measured volume of liquid, subtract the container's mass, and compute density as mass/volume.

What factors affect the rate of evaporation?

Temperature, surface area, humidity, and air circulation (wind speed).

How does temperature affect evaporation?

Higher temperature increases kinetic energy, helping particles overcome intermolecular forces and evaporate faster.

How does surface area affect evaporation?

Greater surface area provides more particles at the surface, increasing the rate of evaporation.

How does humidity affect evaporation?

Higher atmospheric humidity slows evaporation because the air holds more water vapor.

How does air circulation affect evaporation?

Air movement (wind) removes vapor, reducing local humidity and increasing evaporation rate.

What is a density meter used for and give an example range?

Used to measure the density of liquids; example: METTLER TOLEDO DensitoPro; range 0.000 to 3.000 g/cm^3.

What is the chemical formula for water and its atomic composition?

H2O; composed of two hydrogen atoms and one oxygen atom.

What does Figure 3 illustrate about water's states?

Water can exist as solid (ice), liquid (water), and gas (water vapor); energy changes move between these states.

What is an aqueous solution example involving vinegar?

Vinegar is a 5% acetic acid in water aqueous solution.

What is the difference between physical properties and chemical properties?

Physical properties are observed or measured without changing composition; chemical properties relate to how a substance reacts to form new substances.