Energies of Solution Formation

Question 1

Intro

Answer 1

> to answer the question whether a solute will dissolve or dissociate in a solvent

Question 2

Ionic compounds

Answer 2

> compound DISSOCIATES into cations and anions in solvent (i.e. NaCl in water to Na+, Cl-)

Question 3

Solution definition

Answer 3

> a HOMOGENEOUS mixture of a solute in a solvent

> polar and ionic solutes dissolve in polar solvents (i.e. Water)

> non-polar solutés dissolve into non-polar solvents

Question 4

Steps of liquid solution formation

Answer 4

1 - overcome intermolecular forces between SOLUTE molecules, allowing molecules to separate or expand
2 - overcome intermolecular forces between SOLVENT molecules allowing them to separate or expand
3 - allow solute and solvent molecules to mix, creating intermolecular forces between them

Question 5

Type of transfer of energy when in liquid solution formation

Answer 5

Step 1 and 2, overcoming intermolecular forces between solutes, and solvents, absorbed energy from the surroundings, making it endothermic

Step 3, is mixing, releasing energy, making it exothermic

Question 6

Enthalpy change in liquid solution formation

Answer 6

> in endothermic reactions, positive

>exothermic reactions, negative

Question 7

Enthalpy of solution

Answer 7

> sum of enthalpy changed for each of the three steps (can be positive or negative)
positive sum (i.e. Water and oil (polar and non-polar) shows that it requires a lot of energy for solute to mix, therefore, it doesn’t happen
solute will mix with solvent if sum of enthalpy is negative or close to zero (salt in water) due to entropy

Question 8

Entropy

Answer 8

> measure of randomness or disorder in a system

Question 9

Solution formation

Answer 9

> happens in polar-polar, non-polar-non-polar mixes

>splits usually with non-polar and polar mixes