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Matter and Energy Chemistry: The study of matter and its changes Matter: Anything that has mass and volume Physics The study of energy and forces Energy The ability to change or move matter. measured in Joules (J) Kinetic Energy (energy due to motion) All matter has some inherent kinetic energy Types of Energy: Kinetic Energy (Movement Energy) • Thermal Energy (Heat) • Radiant Energy (Light) Potential Energy (Stored Energy) • Gravitational Potential Energy (Relative Position) • Chemical Potential Energy (Energy stored in bonds) Temperature a measure of the average kinetic energy of a sample of matter. 1 Kinetic Molecular Theory 1. “Moving Particle Theory” Matter is made of tiny particles called atoms, which combine to form molecules. 3 Main Ideas: 2. Atoms and molecules are in 3. Atoms and molecules move faster constant random motion (they are always moving) as temperature rises. High Temperature (faster) Low Temperature (slower) Pressure: • “Force per unit area” • Caused by collisions of atoms and molecules All chemical reactions can be written as: chemical equations: for example: Methanol + Oxygen Carbon Dioxide + Water REACTANTS PRODUCTS or: CH3OH + REACTANTS O2 CO2 + HCl / Mg H2O PRODUCTS 2 Law of Conservation of Mass Law of Conservation of Energy “Energy cannot be created or destroyed.” Matter cannot be created or destroyed true, but… …energy can be transferred between a system and its surroundings System: Surroundings: • The part of the universe you are focusing on. • In chemistry, this is usually defined as the products and reactants. Remember: • Everything else in the universe. • In chemistry, this usually includes lab equipment such as thermometers, glassware, probes, containers, and the air in the room. All chemical reactions involve… ENERGY TRANSFER = a release or an absorbtion of energy between the system and the surroundings. Reactants Products Energy and Chemical Bonds • Energy is stored in chemical bonds • Energy is needed to break bonds. • Energy is absorbed when bonds are broken. • Energy is released when bonds form. C6H12O6 + O2 CO2 + 6H2O + Energy(HEAT) Energy absorbed to break these bonds < Energy released to form these bonds Energy and Chemical Reactions: The energy that is transferred between system and surroundings during a chemical reaction can take many forms: heat, light, sound, electricity, movement, …etc. 3 Heat Temperature • Heat is thermal energy • Heat is measured in joules (J) • Heat flows from hot objects to cold objects • Heat flow is evidenced by changes in temperature • When heat is absorbed or released by an object, its temperature changes as a result. • a measure of the average kinetic energy of a sample of matter. • measured in K, oF, oC. Exothermic Reaction: Endothermic Reaction: • Heat is transferred from system to surroundings • Heat is “absorbed” by the system • Heat is “released” from system Container gets HOT • Thermometer (surroundings) will absorb heat and will register a higher temperature. Segue: Thermodynamics • Heat is transferred from surroundings to system • Thermometer (surroundings) will release heat and will register a lower temperature. Container gets COLD Heat (cont.) • The heat energy {measured in joules (J)} that is absorbed by an object can be calculated: Q = m . T . s Q = heat lost or gained m = mass of the system T = change in temperature the system undergoes s = specific heat capacity of the system 4 Specific Heat Capacity (s) Definition: “The amount of heat energy in joules (J) required to increase the temperature of 1 gram of a substance by 1oC Mathematical Formula: Units: s = Q/(mT) J/goC Specific Heat Capacity s (a physical property) – Metals have low specific heat capacity (they are easy to heat up) – Non-metals have higher specific heat capacity (they are hard to heat up) – Water has an unusually large specific heat capacity (it is relatively hard to heat up) (Joules per gram-degree celsius) THE END 5