Thermochemistry

Conservation of energy:energy may be exchanged btw. the materials and the surroundings but the total enrgy of the materials and the surroundings remains constant
Standard heat of reaction:enthalpy change measured inder standard conditions of temp. and press. for thermochemical measurement
Standard heat of formation:heat evolved or absorbed when 1 mole of the substance is formed from its elements under standard conditions
Stand. heat of atomisation:enthalpy change when one mole of gaseous atoms is formed from the element under standard conditions
St. heat of combustion:enthalpy change when one mole of the substance is completely burnt in oxygen under standard conditions


Hess's law of constant heat summation:energy change in converting reactants, A+B, to products,X+Y, is the same,regardless of the route by which the chemical change occurs provided the initial and final conditions are the same
Lattice energy:heat of form. for one mole of the ionic compund from gaseous ions under standard conditions


(CH3OCH3) x2C + 3H2+1/2O2 , CH3OCH3+O2 z y +O2 x=z-y,2CO2+3H2O
N-H bond in NH3:N+3H,3LHat(H2)­ x Hat(NH3)=3N-H,1/2N2 + 3/2H2 w,LHat(N2) ­ y,1/2N2 + 3/2H2 w = x + y - z,LHf(NH3) ,z NH3