Types and rates of Reactions (Vocabulary (temperature: the measure of…
Types and rates of Reactions
Endothermic Definition: a chemical reaction in which heat is taken in
Process of endothermic reactions 1.reactants gain energy from substances used in reaction and gets cold2.eventually heat is absorbed from the surroundings and product returns to room temp. 3. products have more energy than reactants
Exothermic Definition: a chemical reaction in which heat is given out
Exothermic Examples: fireworks going off, reaction of acids with metals, gasoline on fire
Endothermic examples: salts dissolving in water, photosynthesis
process of exothermic reactions 1.chemical energy becomes heat energy 2.the reaction mixture gets hotter3. heat is lost very quickly to surroundings 3. products have less chemical energy than reactants
exothermic reactions are common
Endothermic reactions are rare
exo reactions have a negative heat change
endo reactions have a positive heat change
if it takes more energy to break old bonds than is released when new bonds are formed it is endothermic
if forming new bonds releases more energy than it took to break the old bonds the process is exothermic
ways energy is involved in chemical reactions: to break bonds between reactants and to form new bonds to make new products
temperature: the measure of average kinetic energy of the particles in a material
thermal energy:the sum of kinetic energy and the potential energy of the particles that make up an object
activation energy: energy needed to start a chemical reaction
catalyst: a substance that increases reaction rate by lowering the activation energy of a reaction
inhibitor: substance that slows or stops a chemical reaction
How the state of matter, temperature, pressure, surface area, concentration, and catalysts/inhibitors affect the rate of reactions:
Surface area: When more surface area is exposed the reaction is faster because more of the particles collied. They collide because they are exposed and that makes the bonds break faster.
Temperature: If it is hot the reaction time is quicker. This is because when particles get the heat energy they speed up and when that happens more collisions happen. That makes the bonds break faster. Bonds break slower if it is cold because they have to wait longer to get enough energy.
State of matter: The state of matter changes how much surface area is exposed. If the reactants are solids there will be a slower reaction than if they were liquids.
Pressure: When the pressure increases the particles have less places to move and are pushed together. More collision happen and the bonds break faster making the reaction time less.
Concentration: When the concentration is high there are more particles so more collisions happen. That breaks bonds and decreases the reaction time.
Catalyst: Catalyst lower the amount of activation energy which is needed to start the reaction. The reactants don't have to wait as long to react because they don't need as much energy. The reaction happens faster.
Inhibitor: Inhibitors can attach and make things not work correctly making the chemical reaction slow down or not even happen.