Which of the following equations does not represent a redox reaction? a. NH3+ HCl → NH4Cl
b. 2H2O2+ → 2H2O + O2
c. 2O3 → 3O2
d. 3NO2+ H2O → NO+ 2HNO3
e. LiCl → Li^+ + Cl

a. NH3+ HCl → NH4Cl

c. 2O3 → 3O2

Explanation:

A redox reaction is a reaction in which there is loss or gain of electrons. As  a result of that , there is a change in the oxidation number of the species involved in the reaction.

If we look at the species shown in the answer, there isn't any change in oxidation number as we move from left to right hence they are not redox reactions.

Redox reactions lead to change in oxidation number of species from left to right.

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

"standard molar enthalpy:

h2o ( liquid water ) : - 285.8 kj/mole

h2o ( water vapor ) : - 241.8 kj / mole.

δhrxn = - 241. 8 - ( - 285.8 )= -241.8 + 285.8 = 44.0

answer: 44.0 kj"