thermodynamics 3.1.8 in papers 1 + 3
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how do you work out the standard enhalpy change?
products - reactants
define first ionisation energy
when the outer electron is removed from 1 mole of a gaseous atom to form 1 mole of gaseous 1+ ions
define second ionisation energy
the energy required to remove 1 mole of electrons from 1 mole of gaseous 2+ ions
define first electron affinity
enthalpy change released when 1 mole of electrons is added to 1 mole of gaseous atoms to form 1 mole of gaseous 1- ions
define second electron affinity
the energy required to add 1 mole of electrons to 1 mole of gaseous atoms 1- ions converting them to gaseous 2- ions
define standard enthalpy of atomisation
the enthalpy change when 1 mole of gaseous atoms is produced from an element in its standard state under standard conditions
is the 1st ionisation energy an endothermic or exothermic process and why?
• endothermic • energy is required to overcome electrostatic attraction between the positively charged protons in the nucleus and the outermost negtively charged electron
is the 1st electron affinity an endothermic or exothermic process and why?
• exothermic • electrostatic forces of attraction between positively charged protons and negatively charged electrons which is being adddd to the atom
is the 2nd electron affinity an endothermic or exothermic process and why?
• endothermic • to add a 2nd electron it must be added to a negatively charged ion • energy is required to overcome the electrostatic repulsion between the negatively charged ion and the externally added electron
define the enthalpy change of hydration
the enthalpy change when 1 mole of gaseous ions dissolves in sufficient water to form aqeuous ions in an infintely dilute solution
define the enthalpy of solution
the enthalpy change when 1 mole of ionic solid is dissolved in waterto form aqueous ions in an infinitely dilute solution
how do you work out the enthalp change of hydration?
enthalpy change of solution + enthalpy change of lattice enthalpy of formation
how do you work out the enthalpy change of solution?
enthalpy change of hydration + enthalpy change of lattice enthalpy of dissociation
what is entropy?
a measure of disorder in a system
what is free gibbs energy and its equation?
• the max amount of energy that can be done by a chemical reaction • enthalpy change - (tempreture x enthalpy change of solution)
what is a feasible reaction?
• one that can take place at a particular tempreture • Gibbs energy is equal to 0 or less than
how do you workout enthapy change of solution?
products - reactants
what is the y=mx + c equivilant to gibbs free energy?
y = gibbs free energy m = enthalpy change of a solution x = tempreture c = enthalpy change
why does gibbs free energy decrease when the tempreture increases?
• when T increases the value of - T^S becomes more negative • T is always positive becuase its in K • enthalpy change is constant so it doesnt change
how can you tell a reaction just becomes feasible on a graph?
when the line crosses the x-axis which has a value of gibbs free energy is 0
why do data book values not contain the value of enthalpy of solution for sodium oxide?
reacts with water