The 1995 nobel prize in chemistry was shared by paul crutzen, f. sherwood rowland, and mario molina for their work concerning the formation and decomposition of ozone in the stratosphere. rowland and molina hypothesized that chlorofluorocarbons (cfcs) in the stratosphere break down upon exposure to uv radiation, producing chlorine 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, determine the enthalpy of reaction for the reaction of chlorine with ozone. (1) clo ( g ) + o 3 ( g ) ⟶ cl ( g ) + 2 o 2 ( g ) δ h ∘ rxn = − 122.8 kj mol (2) 2 o 3 ( g ) ⟶ 3 o 2 ( g ) δ h ∘ rxn = − 285.3 kj mol (3) o 3 ( g ) + cl ( g ) ⟶ clo ( g ) + o 2 ( g ) δ h ∘ rxn = ?

Explanation:

The reaction we need to calculate:

1)

We need the ClO in the products side, so we use the inverse of this reaction:

2)

Now we need to combine this two:

The enthalpy of reaction:

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.