Question

The 1995 Nobel Prize in Chemistry was shared by Paul Cutzen, F. Sherwood Rowland, and Mario Molina for their work concerning the formation and decompostion of ozone in the stratosphere. Rowland and Molina hypothesized that chlorofluorocarbons (CFCs) in the stratosphere break down upon exposure to UV radiation, producing chloric atoms. Chlorine was previously identified as a catalyst in the breakdown of ozone into oxygen gas.

Using the enthalpy of reaction for two reactions with ozone, detemine the enthalpy of reaction for the reaction of chlorine with ozone.

(1) ClO(g) + O3(g) -----> Cl(g) + 2 O2(g) ?Hrxn=-122.8 kJ

(2) 2 O3(g) -----> 3 O2(g)

?Hrxn=-285.3 kJ

(3) O3(g) Cl(g) -----> ClO(g) + O2(g)

?Hrxn= ?

?Hrxn = ___________kJ

Answer 1

- Ans Enthalpy En thairy its value depends is an extensive Property Upom amount of reactants. then the # If the given chemical Reaction is reversed Sign of the enthalpy will be also changed. C10(9) + C3 (9) — Cica) + 202() -0 AH,= -122.8KJ -- 20360 – 302.() AH₂ = - 285.3K] 03 (9) + Cleo) - C10(g) + O269) 043 = ? to derive e8-n from the in er order to 0 and get alls, we have ① as - on reversing en 20264+ Clay) -> C1069) + 03(9) - 44 = 122.0 kj By Adding er @ and 4 we get the desired ei as 03 (9) + C149) - CIOCS) + 02 (9) A H3 = chi + H2 = 122.8 – 285.3 = -162.5 ki