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Endothermic and Exothermic Chemical Reactions (Exothermic- Reaction in…
Endothermic and Exothermic Chemical Reactions
Exothermic- Reaction in which heat is given out. The temperature of the surroundings increases.
Examples:
Burning reactions including the combustion of fuels.
Detonation of explosives.
Reaction of acids with metals.
Endothermic - Reaction in which energy is stored. The temperature of the surroundings decreases
Examples: Ice melting, Kettle boiling, Photosynthesis
Endothermic and Exothermic Reactions Steps
Energy Level Diagrams
Exothermic vs Endothermic Energy Level
Burning Methane
Burning Methane #2
Temperature: the degree or intensity of heat present in a substance or object, especially as expressed according to a comparative scale and shown by a thermometer or perceived by touch.
Kinetic Energy: The total amount of kinetic energy
Pressure: continuous physical force exerted on or against an object by something in contact with it.
Collision Theory: explains why different reactions occur at different rates, and suggests ways to change the rate of a reaction. Collision theory states that for a chemical reaction to occur, the reacting particles must collide with one another. The rate of the reaction depends on the frequency of collisions. The theory also tells us that reacting particles often collide without reacting. For collisions to be successful, reacting particles must (1) collide with (2) sufficient energy, and (3) with the proper orientation.
Activation Energy: the minimum amount of energy required to start a chemical reaction.
Catalyst: a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change.
Inhibitor: a substance which slows down or prevents a particular chemical reaction or other process or which reduces the activity of a particular reactant, catalyst, or enzyme.
Law of Conservation of Mass: Matter cannot be created or destroyed in a chemical reaction, just rearranged.
All chemical reactions involve energy.
How the State of Matter affects the Rate of a Reaction: If reactant molecules exist in different phases, as in a heterogeneous mixture, the rate of reaction will be limited by the surface area of the phases that are in contact. If the substances are the same state then they can react smoothly. Therefore, if the substances are two different substances then the reaction rate will decrease.
How Pressure affects the Rate of Reactions: Increasing the pressure on a reaction involving reacting gases increases the rate of reaction. Changing the pressure on a reaction that involves only solids or liquids has no effect on the rate. If there are more molecules in a smaller volume, the chances of collision are greater, and the rate increases.
How Temperature affects the Rate of Reactions: The hotter something gets the faster the molecules move. This mens that the reaction rate will be faster because the molecules have a higher rate of colliding.
How Catalysts affects the Rate of a Reaction: A catalyst is a substance that accelerates a reaction by participating in it without being consumed. Catalysts provide an alternate reaction pathway to obtain products.
How Concentration affects the Rate of reactions: When the concentration of all the reactants increases, more molecules or ions interact to form new compounds, and the rate of reaction increases.
How does Inhibitors affect the Rate of Reactions: Inhibitors slow down reactions and in some cases even stop the reaction.
