$\mathrm{NaCl}$ and KF have the same crystal structure. The only difference between the two is the distance that separates cations and anions. (a) The lattice energies of $\mathrm{NaCl}$ and $\mathrm{KF}$ are given in Table 8.2. Based on the lattice energies, would you expect the $\mathrm{Na}-\mathrm{Cl}$ or the $\mathrm{K}-\mathrm{F}$ distance to be longer? (b) Use the ionic radii given in Figure 7.7 to estimate the $\mathrm{Na}-\mathrm{Cl}$ and $\mathrm{K}-\mathrm{F}$ distances. Does this estimate agree with the prediction you made based on the lattice energies?