Question

2 define standard enthalpy of formation.writeachemical equation for the formation of n2o5

Answer 1

Standard enthalpy of fromation:

It is the change in enthalpy when the 1 mole of substance at standard temperature and pressure is formed from the pure state substance if the same conditions remains.N2O5 is formed from the nitrogen and oxygen which first form nitric oxide and on reacting further with oxygen it will form the N2O5

2*(2 NO + O2  ⇒ 2 NO )   Here Delta H = –114.1 kJ

4NO2 + O22  ⇒  N2O5   here Delta H = –110.2 kJ

2*(N2 + O2⇒2 NO)       Here Delta H = +180.5 kJ

Overall equation will be
2N2 + 5O2 ⇒ 2N2O5

Adding the all Delta H will give the Delta H formation which will be equal to 22.6 KJ