Chemistry of Fuel Footprint

A hydrogen-powered car uses hydrogen gas (H₂) as fuel, which reacts with oxygen (O₂) in the air to produce water vapor (H₂O) in a fuel cell.

During a trip, the car’s fuel system supplies 10.0 moles of hydrogen and the engine draws in 8.0 moles of oxygen from the air.

Record the reaction equation and initial amount of reactants.

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A hydrogen-powered car uses hydrogen gas (H₂) as fuel, which reacts with oxygen (O₂) in the air to produce water vapor (H₂O) in a fuel cell.

During a trip, the car’s fuel system supplies 10.0 moles of hydrogen and the engine draws in 8.0 moles of oxygen from the air.

Which reactant runs out?

• Hydrogen gas

• Oxygen gas

A hydrogen-powered car uses hydrogen gas (H₂) as fuel, which reacts with oxygen (O₂) in the air to produce water vapor (H₂O) in a fuel cell.

During a trip, the car’s fuel system supplies 10.0 moles of hydrogen and the engine draws in 8.0 moles of oxygen from the air.

Which one is limiting reagent?

• Hydrogen gas

• Oxygen gas

Which one is excess reagent?

• Hydrogen gas

• Oxygen gas

What is the amount of excess reagent at the end?

How many moles of H₂O are produced during the reaction?

Hydrogen cars produce no CO₂ during operation, but producing hydrogen fuel often requires energy. If 1 mole of H₂ requires 285 kJ of energy to produce from water via electrolysis, calculate the total energy needed to produce the 10.0 moles of hydrogen.

How could this energy demand for producing hydrogen affect the car’s carbon footprint if the electricity comes from non-renewable sources?

If the electricity for electrolysis came from a renewable source (e.g., solar power with near-zero carbon intensity), how would the carbon footprint of hydrogen production change?