Question

comparison between parallel reaction and opposite reaction in chemical kinetics​

Answer 1

Answer:

1.chain reactions are reactions that are essential similar, but can be represented by a “single” equation. Example: polymerization of ethylene in which first one and then another CH2=CH2 molecule is added to the growing chain, sometimes happening hundreds or even thousands of time in the same product molecule.

2. A chain reaction is an example of a consecutive reaction in that step 2 depends o the completion of step 1, but in a chain reaction the steps are analogous, but a consecutive set of reactions may involve different reagents. Example: the destruction of ozone by methyl chloride:

Step 1: CH3Cl + uv photon → CH3 radical plus Cl atom

Step 2: Cl atom + O2 → ClO2 radical

Step 3: ClO2 radical + O3 (ozone) → CLO + 2O2 molecules

Step 4: CLO + O3 → 2O2 + Cl atom (see step 2)

That is why a single methyl chloride molecule (in the stratosphere where there is ultraviolet light and some particles for the methyl chloride to bond to) can destroy so many ozone molecules.

3. Parallel reactions are ones in which one starting material can either a) form two or more products with a second starting material, o, more commonly, r b) can react competitively with at least two other molecules in the same reaction space. An example of the first is the chlorination of methane, where the first reaction will always produce methyl chloride, while subsequent reactions in the reaction chamber can produce either more methyl chloride (if methane is the reactant) or dichloromethane (if methyl chloride is the reactant) or chloroform (trichloromethane) or carbon tetrachloride (tetrachloromethane}. Notice that this is a specialized case of consecutive reactions.

4. All equilibrium processes are opposing reactions. Thus, when we first dissolve hydrogen chloride in water we have the reaction HCl + H2O → H3O+, + Cl- but as soon the products are formed, the reverse reaction happens and we have the opposite reaction, H3O+ + Cl- → HCl + H2O. After a large number of such cycles the system will come to equilibrium so that the H+ concentration becomes constant (within experimental error) and the solution pH stabilizes.