thermochemistry ⋆｡°✩🥼⋆｡°✩📋

in chemical reactions, energy is absorbed in order to

break atomic bonds

in chemical reactions, energy is released when

new bonds are created

temperature

• measure of random motions of the component of a substance

• how the molecules move

as temp goes UP, speed

goes up (directly proportional)

heat

flow of energy that moves between objects when there is a difference in temperature

calories

the amount of heat required to raise the temperature of one gram of water by 1 degree

exothermic reactions

• reactions that give off heat

• thermal energy is transferred to surroundings

• heat released is greater than heat absorbed

exothermic reactions have the number on

the right

endothermic reactions

• absorb heat to break bonds

• thermal energy is transferred from surroundings to system

• heat absorbed is greater than heat released

endothermic reactions have the number on

left

enthalpy

internal energy/heat content of a substance at constant pressure

things with high enthalphy

• gasoline

• wood

things with low enthalphy

• ash

• water

at constant pressure, heat absorbed/released in a chem reaction is equal to

The enthalphy change of the reaction

• If the reaction releases heat (exothermic), the enthalpy decreases by that amount.

• If the reaction absorbs heat (endothermic), the enthalpy increases by that amount.

if H products is GREATER THAN H Reactants,

• change in H is positive

• endothermic

if H products is LESS THAN H Reactants,

• change in H is negative

• exothermic

enthalphy is depending on

• physical state

• quantity in moles

standard enthalpy of formation

heat change that results when one mole of the compound is form from its elements at standard pressure of 1 atm

the standard enthalphy of formation of any element in its most stable form is

0

standard enthalphy of reaction

enthalphy of a reaction carried out at 1 am

calorimetry

measure of heat flow

calorimeter

apparatus that measure heat flow

specific heat capacity

heat capacity of 1g of a substance (opposed to mole)