Year 13 Physical Flashcards
What is lattice enthalpy
Enthalpy change of formation of one mole of ionic compound from its gaseous ions under standard conditions
Measure of strength of ionic compound
Exothermic
Why cant lattice enthalpy be measured directly
You can’t experimentally form ionic compound from gaseous ions
What is enthalpy change of atomisation
Enthalpy change for formation if one mole of gaseous atoms from the element in its standard state under standard conditions
What is electron affinity
First electron affinity definition
Measures energy to gain electron
Opposite to ionisation
Enthalpy change that takes place when one electron is added to each atom in one mole of gaseous atoms to form one mole of 1- gaseous ions.
Why is first electron affinity exothermic but second is endothermic
First electron is attracted to nucleus but second one has repulsion to the negative ion
What is charge density
Which is more dense Li or K
How spread out a charge is across ion
Li is more dense as they are both same charge but Li is smaller in size
Relate charge density to strength of ionic bond
Higher density of ion the closer the ions can get and therefore the stronger electrostatic force of attraction so stronger bond
What is standard enthalpy change of solution
Enthalpy change that takes place when one mole of solute is completely dissolved in water under standard conditions
Explain step 1 in enthalpy of solution
Breakdown ionic lattice into gaseous ions
Endothermic
Large input of energy required to break electrostatic force between opposite charged ions
Reverse process of lattice enthalpy
Factors that affect the enthalpy of solution
Ionic radius and charge
Explain step 2 for enthalpy change of solution
Hydration of gaseous ions by water molecules
Positive ions attracted to delta negative of oxygen in water
Negative to hydrogen in water
Water molecules completely surround ions
Exothermic as form new electrostatic forces
What is enthalpy change of hydration
Enthalpy change when dissolving one mole of gaseous ions in water under standard conditions
Enthalpy change of solution overall formula
Breakdown of ionic lattice into gaseous ions
Hydratioj of gaseous ions by water
Why does Cl2 gas have highest kinetic energy
Why is Br2 liquid and iodine solid
Very few London forces holding Cl2 molecules together as fewer electrons.
Lowest Ek and stronger london forces
What is a system
What is surroundings
What is universe
Region of space containing matter and energy that is involved in a reaction or progress.
Everything outside of system
System + surroundings
What is standard entropy of a substance
Units
Entropy content of 1 mole of substance under standard conditions
JK^-1mol^-1
Explain entropy
It is a measure of the degree of disorder in a system, it is dispersal of energy and matter.
The more disordered the particles in a system are, higher the entropy
Compare entropy of gas vs solid
Gas has high randomness of particles, high disorder so higher entropy than solid which is opposite of gas
Explain graph of entropy and temp comparing different states and boiling/melting
Always positive grad
Melting has steeper grad than solid followed by liquid followed by boiling which is steeper and longer than melting
Final part is gas which is increasing as temp increases
What is standard entropy change of reaction
Entropy change formula
Entropy change when reaction takes place under standard conditions with molar quantities of each reactant reacting in their standard states
Total entropy of product - total entropy of reactants
