HCFCs vs CFCs: The main difference noted is the presence of hydrogen leading to what?

HCFCs vs CFCs: The main difference noted is the presence of hydrogen leading to what?

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

Answer: (A)

The key idea is how adding hydrogen to CFCs changes their behavior in the atmosphere. Hydrogen in HCFCs makes the molecule more susceptible to oxidation by hydroxyl radicals (OH) in the troposphere. This opens up a degradation pathway, so HCFCs are less stable and break down faster than CFCs, meaning they’re more reactive and have shorter atmospheric lifetimes. That increased reactivity is the direct result of the presence of hydrogen. Because of this, hydrogen “allows oxidation”—the molecule is more readily attacked and broken down by OH radicals. That’s why this option is the best description of the main difference. The other statements don’t fit the mechanism as well: hydrogen doesn’t prevent reactivity; it actually enables it. It doesn’t inherently increase chlorine content (HCFCs have less chlorine than CFCs). And while HCFCs have lower ozone depletion potential, that outcome follows from the higher reactivity and shorter lifetime, not from a direct effect of hydrogen decreasing ozone depletion potential on its own.

The key idea is how adding hydrogen to CFCs changes their behavior in the atmosphere. Hydrogen in HCFCs makes the molecule more susceptible to oxidation by hydroxyl radicals (OH) in the troposphere. This opens up a degradation pathway, so HCFCs are less stable and break down faster than CFCs, meaning they’re more reactive and have shorter atmospheric lifetimes. That increased reactivity is the direct result of the presence of hydrogen.

Because of this, hydrogen “allows oxidation”—the molecule is more readily attacked and broken down by OH radicals. That’s why this option is the best description of the main difference.

The other statements don’t fit the mechanism as well: hydrogen doesn’t prevent reactivity; it actually enables it. It doesn’t inherently increase chlorine content (HCFCs have less chlorine than CFCs). And while HCFCs have lower ozone depletion potential, that outcome follows from the higher reactivity and shorter lifetime, not from a direct effect of hydrogen decreasing ozone depletion potential on its own.