P2
Characteristics Used To Identify a Substance
1. We use chemical and physical properties to identify a substance.
2. Examples of physical properties: color, smell, freezing point, and viscosity
3. Examples of chemical properties: heat of combustion, PH, and electromotive force
Physical Properties vs. Chemical Properties
1. Examples of physical properties: density, luster, and conductivity
2. Examples of chemical properties: reactivity with water, PH, and heat of combustion
3. Physical properties have to do with what an object looks like, while chemical properties have to do with what makes an object’s molecules change
Difference in Physical Properties of Matter
1. Intensive and Extensive
2. Intensive characteristics: don’t depend on amount of matter present, hardness, and malleability
3. Extensive characteristics: depend on amount of matter present, weight, and volume
Physical Change
1. A physical change is when an object’s molecules are moved around, but their internal structures do not change
2. Boiling water, whipping egg whites, and dicing potatoes are three types of physical changes
Chemical Changes
1. A chemical change is when the composition of a molecule changes
2. When the color changes, when energy is released or absorbed, or the odor changes in a substance, that could mean that a chemical change has taken place
3. Wood burning, exploding fireworks, and when food spoils are all examples of chemical changes
Law of Conservation of Mass
1. The Law of Conservation of Mass states that matter is neither created or destroyed and it is only rearranged
2. In chemical reactions, the molecules stay the same, they are just rearranged to form a different substance
Mixtures and Substances
1. A pure substance is a substance that consists of only one component and has a definite composition
2. A mixture is two substances that are mixed but not combined chemically
3. A pure substance has only one