What is unit cell of crystal?
The smallest portion of a crystal which contains all the fundamental properties and acquires the structure of a crystal, without any repetition is called the…
Chemistry
Electron Gain or Electron Affinity
Definition: The electron gain (or electron affinity) (ΔH0eg) is the energy change when one electron is added to each atom to form a negative ion.…
Bond Dissociation Enthalpy
Sometimes the value for the bond dissociation enthalpy is instead given. Note that this bond dissociation enthalpy refers to one bond, so is double the…
Standard Enthalpy of Formation
Standard enthalpy of formation (ΔH0f) Definition: One mole of the compound is formed from its elements in their standard states. For example, sodium chloride (NaCl)…
Describe on Born-Haber Cycle
Lattice enthalpies cannot be determined directly but an application of Hess’s law to the formation of an ionic crystal called the ‘Born-Haber cycle’ can be…
Describe on Lattice Enthalpy
The strength of the covalent bonds can be measured by the bond enthalpy. In ionic compounds the comparable enthalpy value which relates to the strength…
Calculating the Enthalpy Change of a Reaction
The simplest way to apply Hess’s Law is to remember that the enthalpy change of any reaction is equal to the total formation energy of…
Hess’s Law
How can the enthalpy ΔH be discovered if the enthalpy changes for reactions are too difficult or impossible to determine experimentally? If for example, the…
Thermo-chemical Equations
A thermo-chemical equation is a chemical equation for a reaction in which the enthalpy of reaction for the molar amounts stated is written directly after…
Measuring pH Solution
The pH of a solution can accurately be measured using a pH meter. Although less precise, acid-base indicators are often used to measure pH because…
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