0
answers
0
watching
79
views
17 Nov 2019
In the background troposphere, O_3 is formed from photolysis of NO_2. The rate limiting steps for the production of NO_2 (hence, the production of O_3) are HO_2 + NO NO_2 + OH CH_3O_2 + NO NO_2 + CH_3O The corresponding rate limiting reactions for O_3 loss are: O*(^1D) + H_2O 2OH HO_2 + O_3 2O_2 + OH Note that O* is a result of O_3 photolysis. If O* does not react, it will quench and quickly reform O_3. Thus, the reaction with water represents an ozone loss pathway. Derive an expression for the concentration, [NO], where the troposphere changes from net O_3 production to net O_3 loss (that is, the concentration where the production and loss rates are just equal). Calculate a value for [NO] using the expression derived in a) and assuming that [O*] = 0.017 cm^3, [HO_2] = 8.2 times 10^7 cm^-3, [CH_3O_2] = 1.4 times 10^5 cm^-3, [O_3] = 50 ppb, and RH = 50%. Assume a temperature of 298 K and a pressure of 1 atmosphere. The necessary rate constants can be found in the JPL compilation at Plot the expression obtained for a) as a function of RH using the values in b).
In the background troposphere, O_3 is formed from photolysis of NO_2. The rate limiting steps for the production of NO_2 (hence, the production of O_3) are HO_2 + NO NO_2 + OH CH_3O_2 + NO NO_2 + CH_3O The corresponding rate limiting reactions for O_3 loss are: O*(^1D) + H_2O 2OH HO_2 + O_3 2O_2 + OH Note that O* is a result of O_3 photolysis. If O* does not react, it will quench and quickly reform O_3. Thus, the reaction with water represents an ozone loss pathway. Derive an expression for the concentration, [NO], where the troposphere changes from net O_3 production to net O_3 loss (that is, the concentration where the production and loss rates are just equal). Calculate a value for [NO] using the expression derived in a) and assuming that [O*] = 0.017 cm^3, [HO_2] = 8.2 times 10^7 cm^-3, [CH_3O_2] = 1.4 times 10^5 cm^-3, [O_3] = 50 ppb, and RH = 50%. Assume a temperature of 298 K and a pressure of 1 atmosphere. The necessary rate constants can be found in the JPL compilation at Plot the expression obtained for a) as a function of RH using the values in b).