what is the standard enthalpy change of reaction?
the enthalpy change when molar quantities of reactants as specified by the chemical equation react to form products at 298K and 1 bar
what is the standard enthalpy change of formation?
the enthalpy change when 1 mole of substance is formed from its constituent gaseous elements at 298K and 1 bar
what is the standard enthalpy change of combustion?
the heat evolved when one mole of a substance is completely burned in excess oxygen at 298K and 1 bar
what is the standard enthalpy change of atomisation of an element?
the energy required when one mole of gaseous atoms is formed from the element at 298K and 1 bar
what is the standard enthalpy change of atomisation for a compound?
the energy required to convert 1 mole of the compound into gaseous atoms at 298K and 1 bar
what is the standard enthalpy change of neutralisation?
the enthalpy change when 1 mole of water is formed in a neutralisation reaction between an acid and a base at 298K and 1 bar
what is lattice energy?
it is the heat evolved when 1 mole of ionic solid is formed from its constituent gaseous ions
what is bond energy?
the energy required to break 1 mole of a covalent bond in the gaseous state
what is the formula for the weighted average initial temperature?
[(temp of x)(vol of x) + (temp of y)(vol of y)]/(total v)
what is the formula to determine heat change of a reaction?
q=mcT
what is the formula to determine enthalpy change?
enthalpy change = q/n
if exothermic, add a (-) at the front
what is the method to find lattice energy?
borne haber cycle
what is required for a borne haber cycle? (if finding lattice energy)
- enthalpy change of formation of ionic solid
- enthalpy change of atomisation of constituent atoms
- bond energy for non metal - take note of coefficients
- ionisation energy for metal (depending on number of electrons lost)
- electron affinity of non metal (first is negative, subsequent all positive)
what is first electron affinity?
the enthalpy change when 1 mole of electrons is added to 1 mole of gaseous atoms to form 1 mole of singly charged gaseous anions
what is first ionisation energy?
the energy required to remove 1 mole of electrons from 1 mole of gaseous atoms to form 1 mole of singly charged gaseous cations
what is the standard enthalpy change of hydration?
the enthalpy change when 1 mole of free gaseous ions is completely dissolved in an infinite volume of water at 298K and 1 bar
what is the enthalpy change of solution?
the enthalpy change when 1 mole of solute is completely dissolved in an infinite volume of solvent at 298K and 1 bar
what is entropy?
a measure of randomness or disorder in a system, reflected in the number of ways that particle and their energy can be distributed - greater disorder/ randomness, greater entropy
how can we predict change in entropy?
- change in temperature - temp increase, k.e. increase, more ways to disperse the particles and their energy, entropy increase
- change in phase - solid to liquid: particles move more freely in the liquid state, more ways to distribute particles and their energy, entropy increase
- change in no. of particles - no. of gaseous particles increase, no. of ways particles and their energy can be distributed increase, entropy increase
- mixing of particles - particles mixed, volume allowed to occupy increase, no. of ways particles and their energy can be distributed increase, entropy increase (essentially, volume increase, entropy increase)
what is a spontaneous process?
it is a process that takes place naturally in the direction stated
what is gibbs free energy change of reaction?
ΔG = ΔH - TΔS
what does the value of ΔG imply?
ΔG<0: reaction is spontaneous (exergonic)
ΔG>0: reaction is not spontaneous (endergonic)
ΔG=0: reaction is in equilibrium
