Calculating Standard Entropy Change The standard molar enthalpy values,?S?, relate to standard conditions of temperature and pressure The entropy change, ΔS?, can be calculated from thermodynamic d...
斯坦福大學(xué)——“硅谷的核心” 很難講是斯坦福成就了硅谷，還是硅谷成就了斯坦福。毫無疑問，如果沒有硅谷，斯坦福今天最多不過是一所二流偏上的大學(xué)，但是，沒有斯坦福，硅谷恐怕難以支撐他們長達(dá)半個世紀(jì)的繁榮。 ...
Entropy Entropy You may have wondered why it is that?endothermic?reactions occur at all, after all, what can be the driving force behind endothermic reactions if the products end up in a less stabl...
Measuring Energy Changes in the Lab Enthalpies of Solution Calorimetry can be used to find the energy change in chemical reactions. This is much easier to carry out in aqueous solutions We can take...
Dissolution Energy Cycles How are enthalpy of solution and hydration enthalpies related? The relationship between lattice enthalpy, hydration enthalpies and enthalpy of solution From the diagram we...
Born-Haber Cycle Calculations Once a Born-Haber cycle has been constructed, it is possible to calculate the lattice energy (ΔHlat?) by applying Hess’s law and rearranging: ΔHf??= ΔHat??+ ΔHat??+?IE...
Constructing Born-Haber Cycles A?Born-Haber cycle?is a specific application of?Hess's Law?for ionic compounds and enables us to calculate lattice enthalpy, which cannot be found by experiment The b...
Key Enthalpy Terms Ionisation energy The?ionisation?energy?(ΔHIE?) is the standard enthalpy change that occurs on the removal of 1 mole of electrons from 1 mole of gaseous atoms or positively charg...
Hybrid Orbitals Hybridisation The ground state of the electrons in a carbon atom is 1s22s22p2 This can be represented using a spin diagram as shown: Orbital spin diagram for carbon in the ground st...
Ozone Revisited We have seen previously that ozone is a molecule with two resonance structures leading to a resonance hybrid The two Lewis resonance structures for ozone The central oxygen atom has...
Delocalisation & Resonance The delocalisation of electrons can explain the structures of some species that don’t seem to fit with a Lewis structure Delocalised electrons are electrons in a mole...
Formal Charge A limitation of the model of covalent bonding is that when drawing Lewis structures for molecules, it is sometimes possible to come up with more than one structure while still obeying...
