Pollutants & Impacts
The main greenhouse gas and climate driver.
What is CO2?
Fuel property described as “longer range, smaller tanks” when high.
What is high energy density by volume?
The purpose of balancing chemical equations.
What is to conserve atoms and mass?
According to collision theory, reaction rate increases when molecules collide this way.
What is more frequently and with greater energy?
Pollutant associated with lung damage and heart problems; often from fine particles.
What are particulates?
Hydrogen's energy characteristics: high for this measurement but low for this other measurement.
What are high energy per mass and low energy per volume?
This reaction type is represented by fuel + oxygen → products.
What is combustion?
Three factors that increase collision rate
What are higher temperature, higher concentration, and more surface area?
Pollutant group that contributes to smog and ozone formation.
What are NOx (nitrogen oxides)?
The ranking metric that helps decide tank size and range for vehicles.
What is energy density?
When the fuel–air mixture is too rich, these three things often form.
What are CO, hydrocarbons, and soot?
Engine condition that is hotter and can increase NOx formation according to the notes.
What is a lean mixture?
This pollutant binds to hemoglobin and prevents oxygen transport in blood.
What is carbon monoxide (CO)?
Compared to diesel, this fuel produces almost no CO₂ or particulates.
What is hydrogen?
The balancing step that ensures you have the correct amounts of reactants for complete combustion.
What is adjusting coefficients to balance atoms?
Engine condition that tends to produce more soot and CO because of insufficient oxygen.
What is a rich mixture?
Local health concern caused by tiny particles that can enter lungs and bloodstream.
What are particulates?
A practical trade-off for hydrogen: excellent energy per mass but this disadvantage that affects tank design.
What is low volumetric energy density (requires larger/heavier tanks or compression/cryogenics)?
Reaction type that often produces oxygenated products like CO₂ and H₂O and releases energy
What is exothermic combustion?
Device that converts pollutants into less harmful species in exhaust systems.
What is a catalyst (or catalytic converter)?