SACE Stage 1 Chemistry Topic 4

What happens to the solubility of organic molecules as their size increases

It decreases

What increases the solubility of an organic molecule

The number of polar functional groups

Which ions are always soluble in water

Nitrate, Ammonium, and all Alkali metals

Which ions are typically insoluble in water

Carbonate, Phosphate, Silver, Mercury, and Lead

What is the rule if a soluble and insoluble ion are in the same compound

The compound is considered soluble

How does the hydroxyl group in alcohols affect solubility

It can form hydrogen bonds with water molecules

What causes alcohols to become less soluble

A longer non-polar carbon chain

What do emulsifiers contain that allow them to mix polar and non-polar substances

Both polar and non-polar components

What results from adding an emulsifier to a mixture of polar and non-polar substances

An emulsion forms

What is the structure of soaps and detergents

Long non-polar hydrocarbon chains with a negative ionic (anionic) head

What is the ionic head in soaps

A carboxylate ion

What is the ionic head in detergents

A sulfonate ion

What does hydrophobic mean

Water-hating (non-polar)

What does hydrophilic mean

Water-loving (polar)

When does an ionic substance dissolve in water

When water-ion attraction is stronger than the ionic bond

What is a hydration shell

Water molecules surrounding dissolved ions to prevent recrystallisation

How does a precipitate form

By mixing two soluble salts to form an insoluble solid

What is the difference between precipitation and crystallisation

Precipitation is fast and powdery, crystallisation is slow

What type of reactions produce precipitates

Single or double displacement reactions where one product is insoluble

What is a solute

The minor component in a solution

What is a solvent

The major component in a solution

What does miscible mean

Liquids that can mix to form a single liquid

What is the role of an emulsifier in an emulsion

It keeps oil droplets dispersed and the emulsion stable

What interaction occurs when soluble molecules dissolve

Hydration

How do solvent molecules interact with solute ions

They are attracted and surround the ions (e.g. calcium chloride)

What happens when a salt dissolves in water

Ions spread out and are surrounded by solvent molecules

What interaction occurs when NaCl dissolves

Ion-dipole interactions between Na⁺/Cl⁻ and water molecules

Why are some salts insoluble

Ion-ion attractions are stronger than water-ion attractions

What is a double-replacement reaction

A reaction where parts of two ionic compounds exchange to form new compounds

What is dilution

Reducing concentration by adding more solvent

What is a standard solution

A solution with a known concentration made by dissolving a known mass of solute

What is the enthalpy change of solution

∆H = Hproducts – Hreactants (energy gained or lost by surroundings)

How is solution enthalpy calculated

Solution enthalpy = lattice enthalpy – hydration enthalpy

What is the structure of a micelle

Hydrophilic heads face water, hydrophobic tails form an inward core