1. In a hydrogen fuel cell, hydrogen gas and oxygen gas are combined to form water. (1) Write the balanced chemical equation describing this reaction using the lowest whole number coefficients. (2) Identify the oxidizing agent and reducing agent. (3) Determine the number of electrons transferred in the balanced chemical equation

Explanation:

Hydrogen + Oxygen --> Water

(1) Write the balanced chemical equation describing this reaction using the lowest whole number coefficients.

2H2(g) + O2(g) ---> 2H2O(g)

(2) Identify the oxidizing agent and reducing agent.

Oxidizing agent = O (There is decrease in oxidation number from 0 to -2)

Reducing agent = H (There is increase in oxidation number form 0 to  +1)

(3) Determine the number of electrons transferred in the balanced chemical equation

2H2(g) -->  4H+   + 4e- (4 hydrogen atom lost a single electron each)

O2 + 4e-  --> 2O2- (Two oxygen gain 2 electrons each)

Total number of electrons transferred in the balanced chemical equation is 4.

"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"