Question

Consider the equation 2 H2 + O2 → 2 H2O, what does the 2 in the coefficient of H2O molecule represent?

(a) number of particles

(b) the number of molecules

(c) number of moles

(d) number of atoms

This question was addressed to me in a job interview.

Query is from Thermodynamics in division Thermodynamics of Chemistry – Class 11

Answer 1

The correct choice is (c) number of moles

The explanation is: In a balanced thermochemical equation, the coefficients always refer to the number of the moles (but never molecules) of reactants and products involved in a reaction so 2 in the coefficient of H2O refers to the number of the moles of water.