Entropy and enthalpy

Lattice enthalpy definition

The enthalpy change that accompanies the formation of 1 mol of an ionic lattice from its gaseous ions under standard conditions

Is lattice enthalpy exo or endo and why

Lattice enthalpy is exothermic because strong electrostatic forces are formed between the oppositely charged ions to achieve a more stable state

Standard enthalpy change of formation definition

The enthalpy change that accompanies the formation of 1 mol of a substance from its constituent elements in their standard states under standard conditions

What is standard enthalpy of atomisation

The enthalpy change when changing an element into a monoatomic gas

Is enthalpy change of atomisation endo or exo

Endothermic because energy is required to break bonds to form a gas

First ionisation energy definition

The minimum energy required to remove 1 electron from each atom is 1 mol of gaseous atoms to form 1 mol of gaseous 1+ ions

Is ionisation endo or exo

Endothermic because energy is required to overcome the electrostatic forces between the positive nucleus and the negative electron

What is an electron affinity

When an electron is added to an atom/ion

Is the first electron affinity exo or endo

First electron affinity is exothermic as the negative electron is attracted to a positive nucleus

Is second electron affinity endo or exo

Endothermic because energy is required to force an electron toward a negatively charged ion

Standard enthalpy change of solution definition

The enthalpy change accompanying 1 mole of a solute being completely dissolved in a solute Iunder standard conditions

Is enthalpy change of solution endo or exo

Can be either depending on the relative magnitudes of the enthalpy change of hydration and lattice enthalpy

How to draw a dissolved ion

How to find enthalpy change of solution experimentally

Put a thermometer in a polystyrene cup with water and add the ionic solid, use the mass of the solution and c of water in q=mcT to find enthalpy

Enthalpy change of hydration definition

The enthalpy change that accompanies 1 mole of gaseous ions dissolving in water to form 1 mol of aqueous ions under standard condition

What properties of an ion form a stronger lattice

Higher charge, smaller atom (higher charge density)

Ionic size trends across a period

Cations decrease in size left to right, anions decrease in size across the period

What properties of ions cause them have more exothermic hydration enthalpies

smaller ionic size, larger ionic charge (as stronger bonds are formed)

What is entropy

The amount of disorder that there is in a system, a measurement of how the energy is spread outW

Standard entropy definition

Entropy of a substance under standard condition

Entropy of a substance at absolute zero

0, so all other entropys must be positive

What is the entropy change in the changing of states

Entropy change is positive when a substance becomes more random, so solid → liquid or liquid→gas

Would entropy change be +ve or -ve

+ve because a gas has formed which has more entropy

Would entropy change be +ve or -ve

-ve because there are less gaseous moles formed than started