HardChemistryHigh School (11–12)The d- and f-Block ElementsNumerical

Copper has Δa H = 339 kJ/mol, Δi H₁ = 745 kJ/mol and Δi H₂ = 1958 kJ/mol…

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Copper has $\Delta_a H = 339\ \text{kJ/mol}$ , $\Delta_i H_1 = 745\ \text{kJ/mol}$ and $\Delta_i H_2 = 1958\ \text{kJ/mol}$ . Zinc has $126\ \text{kJ/mol}$ , $906\ \text{kJ/mol}$ and $1734\ \text{kJ/mol}$ . Find the energy to turn one mole of each solid metal into gaseous $\text{M}^{2+}$ ions, and the difference.

Need a reminder? The key ideaShow

The nuclear charge rises by one at each step of a series, but a new $3d$ electron screens the $4s$ electrons by about $0.85$ , so $Z_{eff}$ rises slowly. Metal bonds are strong where many d electrons can bond. Enthalpy of atomisation, $\Delta_a H$ , is the energy to turn one mole of solid metal into gaseous atoms. The energy to reach $\text{M}^{2+}(g)$ is $\Delta_a H + \Delta_i H_1 + \Delta_i H_2$ , and hydration returns part of it.

The worked solution

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