The oxidation of SO2 to SO3 is accelerated by NO2. The reaction proceeds according to: NO2(g) + SO2(g) → NO(g) + SO3(g) 2 NO(g) + O2(g) → 2 NO2(g) (a) Show that, with appropriate coefficients, the two reactions can be summed to give the overall oxidation of SO2 by O2 to give SO3. (d) Is this an example of homogeneous catalysis or heterogeneous catalysis?

Verified step by step guidance

1. Step 1: Write down the two given reactions: 1) NO2(g) + SO2(g) → NO(g) + SO3(g) 2) 2 NO(g) + O2(g) → 2 NO2(g)
2. Step 2: Add the two reactions together. To do this, ensure that the number of moles of each species on the reactant side equals the number of moles on the product side for any intermediates. In this case, NO2 and NO are intermediates.
3. Step 3: Cancel out the intermediates. Notice that NO2 appears as a reactant in the first reaction and as a product in the second reaction. Similarly, NO appears as a product in the first reaction and as a reactant in the second reaction. Cancel these intermediates.
4. Step 4: Write the net equation after canceling the intermediates. You should be left with the overall reaction: SO2(g) + 1/2 O2(g) → SO3(g).
5. Step 5: Determine the type of catalysis. Since both the reactants and the catalyst (NO2) are in the same phase (gaseous), this is an example of homogeneous catalysis.

Key Concepts

Catalysis

Catalysis is the process by which the rate of a chemical reaction is increased by a substance called a catalyst. Catalysts work by providing an alternative reaction pathway with a lower activation energy, allowing the reaction to proceed more quickly. In this case, NO2 acts as a catalyst in the oxidation of SO2 to SO3, facilitating the reaction without being consumed in the process.

Reaction Stoichiometry

Reaction stoichiometry involves the quantitative relationships between reactants and products in a chemical reaction. It is essential to balance chemical equations to ensure that the number of atoms for each element is conserved. In the given question, determining the appropriate coefficients for the reactions allows for the correct summation of the individual reactions to represent the overall process of SO2 oxidation.

Homogeneous vs. Heterogeneous Catalysis

Homogeneous catalysis occurs when the catalyst and the reactants are in the same phase, typically in a solution, while heterogeneous catalysis involves a catalyst in a different phase than the reactants, often solid catalysts with gaseous or liquid reactants. In the provided reaction, since NO2 and SO2 are both gases, this is an example of homogeneous catalysis, as all species involved are in the same phase.