Concept 2: Properties of Matter

Volume

- Volume is measured in mL or cm^3, using 2 different methods. - Volume of a solid: If a regular shape, use a ruler and the appropriate geometric equation. - Cube or rectangular prism: V = l × w × h - Cylinder: V = π × r^2 × h - Measured in cm^3. Volume of a liquid: If a liquid or an irregularly shaped solid, use a graduated cylinder (and water displacement for a solid) - Measured in mL. - Water Displacement: 1.) Put enough water in the graduated cylinder to cover the object. 2.) Record initial volume. 3.) Add object. 4.) Record final volume, with object in it. 5.) Subtract v^f - v^i to find the volume of the object.

A piece of plastic with a mass of 15 g is placed in a graduated cylinder. The water level in the graduated cylinder rises from 30 mL to 55 mL when the plastic is added. Find the density of the plastic.

0.6 g/mL

A piece of metal is 4 cm by 10 cm by 2 cm. Find its mass if it has a density of 2 g/cm^3.

160 g

Viscosity

A fluid's resistance to flow. - A physical property only of liquids. - Can change with temperature. - Think "how thick it is". - Ex. Viscosity of syrup is high and water is low.

Solubility

A measure of how well a solute dissolves in a solvent.

Oxidation

How easily a substance reacts with oxygen. - Ex. Iron reacts with oxygen and moisture to create rust.

Reactivity

How easily a substance reacts, usually with an acid or base. - Ex. Fluorine gas is highly reactive and will spontaneously ignite a concrete block at room temperature.

Combustibility

How easily a substance will set on fire. - Ex. Burning charcoal.

Law of conservation of matter

Matter is neither created or destroyed during a chemical change. It only changes forms. - Mass cannot be "lost", even when a chemical reaction happens.

Density

Measure of compactness or consistency of a material. - Mass per unity of volume. - Measured in g/cm^3 or g/mL. - Density doesn't change, regardless of size. - Mass is measured in grams (g), using a scale. Density = mass / volume

Explain the difference between physical changes and chemical changes.

Physical Change: A change in a substance that only affects its physical properties. - Ex. Cutting, coloring, crushing, melting, boiling, etc. Chemical Change: A change in a substance that affects its chemical properties thus a chemical reaction occurs and a new substance is formed. - Ex. Burning, rusting, decomposing, etc.

Explain the difference between physical properties and chemical properties, and list three example of each.

Physical Properties: Properties that can be observed directly or measured without changing the chemical identity of the substance. - Ex. Mass, volume, shape, size, color, luster, hardness, etc. Chemical Properties: Properties that can only be observed or measured by changing the chemical identity of a substance. - By observing it, a new substance is formed. - Ex. Toxicity, flammability, combustibility, radioactivity, etc.

Boiling point

Temperature at which a liquid becomes a gas.

Melting point

Temperature at which a solid becomes a liquid.

Chemical reaction

The process by which the atoms of one or more substances are rearranged to form different substances.

Solution

The result. - Ex. Lemonade.

Solute

What is being dissolved. - Ex. Lemonade powder.

Solvent

What is doing the dissolving. - Ex. Water.

Classify the following changes as physical or chemical. a.) Boiling b.) Crumpling c.) Burning d.) Freezing e.) Evaporating f.) Rotting g.) Rusting h.) Sawing i.) Crushing

a.) Physical b.) Physical c.) Chemical d.) Physical e.) Physical f.) Chemical g.) Chemical h.) Physical i.) Physical