What is the role of hydrogen in HCFCs compared to CFCs?

What is the role of hydrogen in HCFCs compared to CFCs?

• A. Hydrogen allows oxidation making HCFCs reactive
• B. Hydrogen prevents reactivity
• C. Hydrogen increases chlorine content
• D. Hydrogen decreases ozone depletion potential

Answer: (D)

Hydrogen in HCFCs makes the molecules less stable in the lower atmosphere, so they are more readily broken down by hydroxyl radicals in the troposphere. This shortens their atmospheric lifetime, meaning less chlorine is carried up into the stratosphere where it would catalytically destroy ozone. Because of this reduced chlorine delivery to the ozone layer, HCFCs have a much lower ozone depletion potential than CFCs, which are fully halogenated, very stable, and persist long enough to release chlorine in the stratosphere. In short, the presence of hydrogen accelerates atmospheric degradation of HCFCs and limits the chlorine available to deplete ozone, leading to a smaller ozone depletion potential.

Hydrogen in HCFCs makes the molecules less stable in the lower atmosphere, so they are more readily broken down by hydroxyl radicals in the troposphere. This shortens their atmospheric lifetime, meaning less chlorine is carried up into the stratosphere where it would catalytically destroy ozone. Because of this reduced chlorine delivery to the ozone layer, HCFCs have a much lower ozone depletion potential than CFCs, which are fully halogenated, very stable, and persist long enough to release chlorine in the stratosphere. In short, the presence of hydrogen accelerates atmospheric degradation of HCFCs and limits the chlorine available to deplete ozone, leading to a smaller ozone depletion potential.