Water for chemistry/solubility

how do Aqueous solutions form

form when a solid, liquid or gas (solute)dissolve in water (solvent)

Aqueous solutions

Properties

• solute particles too small to be seen and can vary in amount

• solvent + solute cannot be seen individually

Why does water have low density as a solid

• This is due to it forming a lattice as a solid.

• having up to 4 bonds

Dissolution or not
Polar-polar

dissolution

Dissolution or not

non polar-non polat

dissolution

Dissolution or not

polar-non polar

no dissolution

whats dissolution

The process of dissolving substances

universal solvents

like water, can dissolve a wide range of substances due to their polar nature. resulting in separation of various solutes

what happens during dissolution

• the solvent particles separate

• the solute particles separate

• solute and solvent particles are attracted to each other

why are most molecular substances insoluble in water

due to them having weak IMF

What are 2 ways molecular substances can become soluble

H-bonds and ionisation

Solubility via H-bonds

Dissolution occurs and it requires a lot of energy to break off

What happens when a substance what forms H-bonds dissolves in Water

• The H-bonds break apart and form new bonds with the water

solubility with ionisation

molecules having strong covalent bonds that are so polar they break in water=ions

eg. HCL ionises into H and Cl when dissolved in water

Dissolution of ionic lattice

What happens to the lattice when it dissolves

When it dissolves the positive end of the water molecules become attracted to the negative end of the substances and vice versa

how can the outer layer of the lattice be removed

If dipole forces between water and ions is strong enough it'll break These free ions= hydrated

whats dissociation

the process of a solid ionic compound dissolving in water to form hydrated ions

What can break the lattice

ion dipole forces between one ion and several H20s. These dipole attractions form new bonds between H20 and ions

properties of water

High MP/BP

Due to H-bonds a large amount of energy is needed to break it and as the molecules size increase so does its dispersion forces resulting in the need of higher BP

• properties of water

water as a solid

it forms a crystal lattice and is less dense than liquid allowing it to float

When does crystallization occur

occurs when an unsaturated solution becomes saturated​

what are 2 ways crystallisation occurs

Evaporation and cooling

define how evaporation leads to crystallisation

When a solvent evaporates, the solubility of the solution decreases causing the solute to become a solid​

define how cooling leads to crystallisation

If an unsaturated solution is cooled, it will eventually reach saturation if you keep cooling it, it becomes supersaturated= crystals​​

Crystal Growth

How is a crystals size and shape determined by Rate of cooling

​

• slow cooling=large crystals as they have time to grow,
  Fast cooling= smaller crystalls

Crystal Growth

How is a crystals size and shape determined by Rate of solvent evaporation

• Fast evaporation = small crystals​

• Slow evaporation = large crystals​

Crystal Growth

How is a crystals size and shape determined by Nucleation:

Crystallisation occurs quicker if a seed crystal or ‘nucleus’ is added​

Crystal Growth

How is a crystals size and shape determined by Nature of Compound:

by the molecular structure, bonding type and strength of bonding, growth conditions,​

Whats solubility

The maximum amount of soulte that can be dissolved in a solvent at a certain temperature

When dissolving solutes into solvents what 3 types of solutions form

• Saturated solutions: no more solute dissolves

• Unsaturated solution: more solute dissolves

• Supersaturated: Becomes unstable and crystals form

Solubility of liquids and gases

Liquids don’t show solubility trends

Gases tend to be less soluble in water at high temp

How does a precipitation reaction occur

If ions in a solution combine to form an insoluable compound

How to predict precipitation reactions

1. Identify the ionic compund

2. swap the anions

3. see if the new ionic compound goes against the solubility table

4. identify the ppt if any

grams per litre, g/l formula

Mass of solute (g)
-----------------
V of solvent (L)

parts per million ppm formula

mass of solute (mg)
-------------------
mass of solvent in (kg)

percentage composition

mass of solute (g) 
-----------------       x 100
mass of solvent (g)