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Chapter 1 Section 1.2. Properties and Changes of Matter. Physical and Chemical Properties. Properties (characteristics) of matter can be described as either: Physical Chemical. What is a Physical Property?. These are properties that don’t involve changes in composition.
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Chapter 1Section 1.2 Properties and Changes of Matter
Physical and Chemical Properties Properties (characteristics) of matter can be described as either: • Physical • Chemical
What is a Physical Property? • These are properties that don’t involve changes in composition. • Qualitative examples: • The solution is blue • The tree is tall • The butter is soft • The liquid freezes at a low temperature • Quantitative examples: • Ice melts at 0°C • Iron has a density of 7.86g/mL
Physical Properties • State of matter (change in state) • Conductivity • Magnetic • Color • Melting point, boiling point • Density • Malleability
What is a Chemical Property? • These are properties that can be observed when there IS a change in the composition of the substance. (Change in composition) • Examples: • Oxidizer • Reactive • Flammable
Physical Change • Change of matter where its identity does not change (Doesn’t change what it is) • Cutting of paper • Sharpening of pencil • Ice melting into water
Chemical Change • Change of matter where its identity is changed (Changes what it is). Usually related to a chemical reaction. • Decomposition • Explode • Rot • Rust (oxidation) • Color change • Tarnish • Ferment
How do I know if it is a Chemical or Physical Change? • Ask the question – Do you end up with the same stuff you started with? • Yes, physical change • No, chemical change
Chemical Change and Atoms • Law of conservation of mass (matter) • - In a chemical change, matter is neither created nor destroyed. • Example: CH4 + 2O2 CO2 + 2H2O No atoms are gained or lost…
Chemical Change and Energy • Energy is the capacity to do work. Energy is either absorbed or released in a chemical change. • Chemical reactions that give off heat energy are called exothermic reactions • Chemical reaction that absorb heat energy are called endothermic reactions
Endothermic Examples • Absorbs heat and cools surroundings • Melting (ice cubes) • Cooking an egg • Evaporation of sweat • Photosynthesis • Baking soda when baking
Exothermic Examples • Gives off heat and increase temp of surroundings • Burning wood • Digestion of food • Freezing • Cellular Respiration • Metabolism • Combustion of ammonium nitrate
Exothermic and Endothermic • http://www.kentchemistry.com/links/Matter/EndoExo.htm