Reactivity 3.3—Electron sharing reactions: Practice Questions

Which of the following describes the first step of an electron sharing reaction between methane (\(CH_4\)) and chlorine (\(Cl_2\)) in the presence of UV light?

In the electron sharing mechanism of the ozone depletion cycle by CFCs, which step represents the propagation phase?

Consider the thiocyanate ion ($$SCN^-$$). Which of the following is the most plausible Lewis structure based on formal charges?

(Valence electrons: S=6, C=4, N=5)

When a chlorine molecule (\(Cl_2\)) undergoes homolytic fission in the presence of ultraviolet light, what species are produced?

Which of the following identifies the Lewis acid and the Lewis base in the formation of the complex ion \( [\text{Fe}(\text{H}_2\text{O})_6]^{3+} \)?

Consider the reaction between methane and chlorine in the presence of UV light. Write the chemical equation for the initiation step of this electron sharing reaction and identify the type of bond fission involved.

Consider the reaction mechanism of the free-radical substitution between methane (\( \text{CH}_4 \)) and chlorine (\( \text{Cl}_2 \)) in the presence of ultraviolet (UV) radiation.

(a) Explain why UV radiation is necessary for the initiation step and write the balanced equation for this step, including the type of bond fission involved.
(b) Provide the two propagation steps for the formation of chloromethane (\( \text{CH}_3\text{Cl} \)). Use fishhook arrows conceptually to describe the electron sharing involved.
(c) Trace amounts of ethane (\( \text{C}_2\text{H}_6 \)) are often detected in the final reaction mixture. Identify the specific termination step that leads to the formation of ethane and explain why this occurs even though the intended product is a chlorinated alkane.
(d) Suggest, with a reason, how the concentration of the reactants could be adjusted to favor the production of tetrachloromethane (\( \text{CCl}_4 \)) rather than chloromethane.