Oceans

Question 1

Solubility of Ionic Substances

Answer 1

Only dissolve in polar solvents, as ion-dipole bonds are formed, the 𝛅- and 𝛅+ circle the positive and negative ions.
Non-polar solvents don’t interact strongly enough to overcome the electrostatic forces between the ions.

Question 2

Solubility of Covalent Substances

Answer 2

Only dissolve in non-polar substances, as the intermolecular forces between the covalent molecules are weak.
Polar molecules have too strong dipole bonds to allow covalent molecules to dissolve.

Question 3

Define Lattice Enthalpy

Answer 3

The standard lattice enthalpy is the enthalpy change when 1 mole of an ionic lattice is formed from its gaseous ions under standard conditions.

Question 4

Define Enthalpy Change of Hydration

Answer 4

The enthalpy change of hydration of ion is the enthalpy change when 1 mole of aqueous ions are formed from gaseous ions.

Question 5

Define Enthalpy Change of Solution

Answer 5

The enthalpy change of solution is the enthalpy change when 1 mole of an ionic substance dissolves in enough solvent to form an infinitely dilute solution.

Question 6

Effect of Charge Density on Enthalpy

Answer 6

• Lattice Enthalpy - Greater Charge Density means stronger ionic bonds. So more energy is released when bonds are made so more exothermic.
• Enthalpy of Hydration - Greater Charge Density means more attraction to the water molecules so more energy is released when bonds are made so more exothermic.

Question 7

Define Entropy

Answer 7

Entropy, S, is a measure of the number of ways that particles can be arranged and the number of ways that energy can be shared out between the particles.

Question 8

Factors that effect Entropy

Answer 8

• Physical State - Gas has highest entropy and Solid the lowest.
• The more energy the more disorder.
• More particles means more entropy.

Question 9

How do you calculate Total Entropy Change

Answer 9

ΔtotS = ΔsysS + ΔsurrS
ΔsysS = Sproducts - Sproducts
ΔsurrS = - ΔH / T
ΔH - Enthalpy Change

Question 10

What is the Solubility Product?

Answer 10

The equilibrium constant for a saturated solution of a sparingly soluble solid in water.
AₐBₑ (s) ↔ aA⁺ (aq) + eB⁻ (aq)
Ksp = [A⁺(aq)]^a x [B⁻(aq)]^e

Question 11

Bronsted-Lowry Acid

Answer 11

Bronsted-Lowry acids are proton donors, they releases hydrogen ion (H⁺) when they’re mixed with water.
HA (aq) + H₂O (l) → H₃O⁺ (aq) + A⁻ (aq)

Question 12

Bronsted-Lowry Base

Answer 12

Bronsted-Lowry bases are proton acceptors, when they’re are in solution they grab hydrogen ions from water molecules.
B (aq) + H₂O (l) → BH⁺ (aq) + OH⁻ (aq)

Question 13

How do you calculate pH?

Answer 13

pH = -log₁₀[H⁺]

Question 14

[H⁺] in Strong Acids

Answer 14

Monoprotic Acids: ie HCl, HNO₃
[H⁺] = [Acid]

Question 15

Titration Method

Answer 15

· Use a measure quantity of a standard solution.
· Pipettes and Burettes to measure precisely.
· Indicator is used to show when it has been neutralised, often phenylalanine or methyl-orange.
· Read volume of known concentration was used.