How many liters of oxygen (O2) are required to produce 50 liters of water (H2O) if there is excess hydrogen (H2)? 2 H2 + O2 → 2 H2O

2 liters O2

25 liters O2

50 liters O2

100 liters O2

Which best describes the activation energy of a chemical reaction? a. the combined energy of all the reactants b. the amount of energy required for a reaction to occur c. the difference in energy between products and reactants d. the potential energy stored in the bonds of reactants and products