Lattice Energy Question

Question

Does NaCl or Na₂O have the largest lattice energy?

Answer 1

Hi Jack,

I'd be happy to help you with this question. In the absence of numerical values, we can estimate the relative lattice energies of ionic compounds based on coulomb's law:

E = k(|Q₁Q₂|)/r

Where E represents the lattice energy, k is a constant, Q₁/Q₂ are the charges of the ions making up an ionic compound, and r is the distance between the atoms making up the ionic compound.

According to this equation, the larger the charge and the shorter the distance between the ions making up an ionic compound, the stronger the attraction, and thus the higher the lattice energy.

Now, let's apply this concept to NaCl and Na₂O.

First, looking at the chargers of the two compounds, NaCl is made of Na⁺ and Cl^- while Na₂O is made of 2Na⁺ and O^2-. So, Na₂O has the greater charge overall. This suggests that Na₂O will have the larger lattice energy.

Second, looking at the distance between the two ions, we must consider the size of the anion (since Na⁺ is the cation in both cases. O^2- is smaller than Cl^-, meaning it will be closer to the Na⁺, and thus a shorter distance between the two ions. This also suggests that Na₂O will have the larger lattice energy.

In summary, Na₂O is predicted to have a larger lattice energy.

(In fact, this is supported by experimental values: NaCl has a lattice energy of 787.3kJ/mol, while Na₂O has a lattice energy of 2564 kJ/mol)

Hope this helps! Feel free to message me with any follow-up questions.

Best,

Chris