Energy Chem 30 Ap

• enthalpy is the total internal energy of a system 
• enthalpy change is the energy released or absorbed by a system

molar enthalpy is the amount of energy released or absorbed by one mole of a substance

no but you can determine the enthalpy change by determining the energy change from the enviorment

energy is released when bonds are formed so the temperature of the surroundings increases

energy is absorbed to break the bonds so temperature in the surrounding decreases

Left is exothermic potential energy goes down right is endothermic potential energy goes up

labels are ep and reaction pathway

collision theory states that reactant particles must collide for a reaction to occur but only a certain amount of the total collisions will result in a chemical reaction

2 requirements- the right orientation at the moment of impact, the minimal amount of activation energy needed

a catalyst is a substance that speeds up the rate of chemical reaction without being consumed in the reaction they do this by lowering the activation energy.

• cdc-used to catalyze 03 into 02
• nitric acid- used in fertelizer
• sulfric acid- used in oil industry
• enzymes-our body
• catalytic convertors in cars- turn no and co into nitrogen gas and co2

• open system-matter and energy can be exchanged
• closed- matter cannot be exchanged but energy can
• isolated- neither can be exchanged

a calorimeter is a isolated system that is used to measure heat released or absorbed by a physical or chemical process 

• -Isolated system does not allow products to escape or thermal energy to be transferred to surroundings
•  -calorimeter does not absorb heat itself
• -contains a small amount of water to help with energy transfer.

• exo- temp of water increases
• endo- temp of water decreases

a closed system with changing pressures as the combustion reaction proceeds so water product is liquid not gas

• law one-energy cannot be created or destroyed only transferred
• law two- thermal energy is transferred from an object with a higher temperature to an object with lower temperature to create equilibrium