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Conservation of Mass and Energy. (or what Lavoisier got so worked up about). O. O. O. H. H. H. H. Conservation of Mass. What two elements make up water? Hydrogen and Oxygen! Both are diatomic, so the equation for the formation of water should look like:. reactant side. product side.
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Conservation of Mass and Energy (or what Lavoisier got so worked up about)
O O O H H H H Conservation of Mass • What two elements make up water? • Hydrogen and Oxygen! • Both are diatomic, so the equation for the formation of water should look like: reactant side product side What’s wrong with this picture?
O O O O H H H H H H H H Conservation of Mass • Here’s what it should look like: reactant side product side
Definitions • Conservation of Mass: • In chemical or physical changes, no mass is ever gained or lost, just moved around. • Remember Lavoisier!
More Definitions • Conservation of Energy • In chemical and physical changes, no energy is ever gained or lost, just transferred from one form to another. • Kinetic vs. Potential Energy
Combined Law • Conservation of Mass & Energy: • Mass and energy are never gained or lost in chemical or physical changes. • Energy and mass MAY be changed into one another through fission or fusion: E=mc2
Properties of Matter (or what it looks & acts like)
What are properties of matter? • Properties of a substance: • The set of characteristics by which a substance is recognized. • Ex. Water: • Boils at 100 °C • Melts at 0 °C • Is wet • Is clear (when pure)
Properties of Matter • Properties describe what can be observed directly or indirectly about a substance, and the way the substance acts or reacts.
Extensive Properties • Properties that depend on the amount of the substance: • Volume • Mass • Length • Weight • NOT good for identifying substances
Intensive Properties • Properties that do NOT depend on the amount of the substance: • Melting point • Boiling point • Density • Chemical Reactivity • Color • Smell • ARE good for identifying substances!