Which pathway?

You will build a small decision rule for the main pathway of a haloalkane, and two calculations that go with it: the share of $S_{\text{N}}2$ in a mixed reaction and the temperature at which elimination catches up.

The idea. A primary halide does $S_{\text{N}}2$, unless the base is bulky, when it eliminates. A tertiary halide cannot do $S_{\text{N}}2$. A secondary halide depends on the reagent. A higher temperature favours elimination.

Your tasks.

1. Complete pathway(kind, reagent). The reagent is "weak", "good nucleophile", "strong base" or "bulky base".
2. Complete sn2_share(k1, k2, nu), the percentage of the reaction that goes by $S_{\text{N}}2$ when the rate is $k_1 + k_2[\text{Nu}]$ per unit of haloalkane.
3. Complete crossover(dh, ds), the temperature in K at which elimination and substitution are equally fast, from $\Delta\Delta H$ in J/mol and $\Delta\Delta S$ in J/(mol K).