The standard enthalpy of formation. The enthalpy of formation is the energy change when 1 mole of a substance is formed from its constituent elements in their standard states.Particular points to note: 1  The elements are in their usual states under standard conditions. i.e at 25ÂºC and 1 atmosphere pressure (100 kPa).he standard enthalpy of formation. The enthalpy of formation is the energy change when 1 mole of a substance is formed from its constituent elements in their standard states.
Microsoft bumped the layout to 104 keys with the addition of Windows keys and a Menu key a bit later, but the layout is essentially the same. This is a rule-of-thumb, as no two keyboards are exactly the same. The number of keys on a full size keyboard varies, some having media keys, etc.
In the Western tradition of music, there are basically twelve keys, corresponding to the twelve notes of the chromatic scale on a keyboard instrument (ie C, C#, D, D#...etc all the way up to C again). But as these can be either major or minor, we end up with a total of 12 major + 12 minor = 24 possible keys.