(a) Based on the lattice energies of MgCl2 and SrCl2 given in Table 8.1, what is the range of values that you would expect for the lattice energy of CaCl2?

Video transcript

Hi everyone for this problem we're told the lattice energy of sodium iodide is 682 kg per mole, while that of sodium chloride is 788 kg joules per mole. We need to estimate the lattice energies of sodium bromide. Okay, so let's recall what lattice energy is. Lattice energy is equal to negative Q one times Q. Two over R. And lattice energy. And our which is our ionic radius have an inverse relationship. So what happens to one? The opposite happens to the other? And when we look at the periodic table, we can look at the ionic radius for chlorine, bruning and iodide. So I are ionic radius gets bigger as we go up. Okay, so we have Corinne has the smallest ionic radius and then it's bruning and then it's iodine. Okay, so that means our lattice energy is going to have an inverse relationship to this. Okay, so when it comes to our compounds are lattice energy reflects the opposite. So that means our sodium chloride is going to have the greatest lattice energy and then it's going to be sodium bromide. And then sodium iodide. Okay, because of that inverse relationship. And so we were given the lattice energies of sodium bromide. And know we're given the lattice energies of sodium iodide and sodium chloride. So that means that our lattice energy are estimated lattice energy of sodium bromide is going to fall in between the two. So, for sodium chloride, Our lattice energy is killer joules per mole. So that's going to have the largest and then our sodium bromide will fall in the middle, And then our sodium iodide, which were given the lattice energy of 682 killer jewels per mole, will be the smallest. So this is going to be our final answer when we estimate the lattice energy of sodium bromide, it's going to fall in between these two, with sodium chloride having the largest. Okay, that's the answer to this problem, and that's the end of this problem. I hope this was helpful.