# Physical vs. Chemical Properties

## Presentation on theme: "Physical vs. Chemical Properties"— Presentation transcript:

Physical vs. Chemical Properties
Part 1 The study of matter

NC Essential Standards
8.P.1 Understand the properties of matter and changes that occur when matter interacts in an open and closed container 8.P.1.1: Classify matter as elements, compounds, or mixtures based on how the atoms are packed together in arrangements 8.P.1.2: Explain how the physical properties of elements and their reactivity have been used to produce the current model of the Periodic Table of Elements 8.P.1.3 Compare physical changes such as size, shape and state to chemical changes that are the result of a chemical reaction to include changes in temperature, color, and formation of a gas or precipitate. 8.P.1.4: Explain how the idea of atoms and a balanced chemical equation support the law of conservation of mass.

Reviewing MATTER Matter: anything that has mass and takes up space
Mass – the amount of matter in something Volume – the amount of space something occupies Which of the following is matter? A car? A box? You?

What is a property? Property: a characteristic of a substance that can be observed

Physical Property Physical property: a property that can be observed without changing the identity of the substance. Examples: luster malleability: the ability to be hammered into a thin sheet ductility: the ability to be stretched into a wire melting point boiling point density solubility specific heat

Special Physical Properties
Melting point: the temperature at which a substance changes from a solid to a liquid at a given pressure water = 0oC Boiling point: the temperature at which a substance changes from a liquid to a gas at a given pressure water = 100oC

Chemical Properties Chemical property: a property that can only be observed by changing the identity of the substance Examples: flammability ability to rust reactivity with vinegar

Density Density is the amount of mass per unit of volume.
Density can be used to identify a substance. The density of water is 1.0g/mL

Density Calculations Calculations:
D = m/V = g/mL = g/cm3 Ex: A cube has a mass of 2.8 g and occupies a volume of 3.67 ml. Would this object float or sink in water? Mass = 2.8 g Volume = 3.67 mL D = 2.8g/3.67 mL= 0.76 g/mL This object would float in water because its density is less than water (1.0 g/mL).

More Density Calculations
Ex: A liquid has a mass of 25.6 g and a volume of 31.6 mL. Use the table below to identify the substance. M=25.6 g V=31.6 mL D = 25.6 g/31.6 mL D= 0.81 g/mL The substance is ethanol.

Physical vs. Chemical Changes
Part 2

Concept of Change Change: the act of altering a substance
Change of state/phase – Solid, Liquid, Gas

Physical Change Physical change: a change that occurs that does not change the identity of the substance Melting ice Freezing Kool-aid Tearing paper Boiling water

Chemical Changes Chemical change: a change that occurs that causes the identity of the substance to change Burning Digesting food Reacting with other substances A chemical change is called a chemical reaction

Chemical Changes Cont’d
Indicators of a chemical change: Evolution of light Evolution of heat Evolution of a gas Color change Formation of a precipitate A precipitate is a solid substance that forms as a result of a chemical reaction

Is it Physical or Chemical?
Change Physical Chemical Melting cheese Burning wood Milk souring Wadding up paper Bicycle rusting