U2 CHEM chemical energetics

state enthalpy change

heat energy transferred between a system/surrounding under constant pressure, reactions either absorb/release energy

what is an endothermic reaction

reactions that absorb heat energy from surrounding

what is an exothermic reaction

reactions that release heat energy to surroundings

help me understand standard enthalpy change of FORMATION

when 1 mol of substance is formed from its element in their standard states under standard conditions

STANDARD ENTHALPY CHANGE OF COMBUSTION

heat energy released when 1 mol of substances is combusted completely in oxygen under standard conditions

standard enthalpy change of reaction

heat energy change occurs when 1 mol of the reaction equation takes place under standard conditions

define HESS LAWS

whether reaction takes place in 1 or 2seps total enthalpy change of reaction will still be the same

define dynamic equilibrium

• both forwards and backwards reactions are happening same rate on a molecular level

factors that affect EQ

• concentration

• pressure

• temp

• catalyst

define le chateliers principle

system at equilibrium is subject to change system will shift partially to counteract the change