Properties + Properties of Water

Physical Properties

the physical characteristics of the substance, tells us how the substance behaves physically, doesn’t say anything about how the substance behaves chemically

absorption, angular momentum, area, brittleness, bp, capacitance, colour, concentration, density, ductility, elasticity, electric charge, electrical conductivity, electric field, electric potential, flow rate, fluidity, frequency, hardness, heat capacity, length, location, luminescnece, malleability, magnetic field, mass, mp, momentum, permeability, plasticity, pressure, resistivity, reflectivity, solubility, specific heat, stiffness, temp, tension, thermal conductiviy, velocity, viscosity, volume

Important for IMAT

Boiling point: temperate at which a chemical boils, i.e., liquid to gas, depends on what type of chemical, depends on pressure, high pressure = high boiling point

Melting point: the temperature at which a chemical melts (solid to liquid), depends on type of chemical, depends on pressure, generally, higher pressure = higher melting point, Exception: ice to water

Freezing point: the temperature at which a chemical freezes (liquid to solid) depends on type of chemical, depends on pressure, generally higher pressure = higher freezing point

Exceptions (there are many): water to ice

For melting point and freezing point there are quite a few exceptions, so it’s not really a general rule of how pressure impacts the freezing or melting point.

Chemical Properties

the chemical characteristics of the substance

Heat of combustion

Explosivity

Enthalpy of formation

Toxicity

Chemical stability

Flammability

Preferred oxidation state

Ability to corrode

Combustibility

Acidity/Basicity

Phase Change: the transition from one physical state of matter to another

Is a physical process, influenced by both temperature and pressure

Boiling point

Melting point

Triple point: unique temperature and pressure at which solid, liquid and gas all coexist in equilibrium

Critical point: temperature and pressure at which liquid and gas phases become indistinguishable. Liquid and gas basically become the same phase (supercritical fluid)

Phase Changes

From Solid….

To liquid: melting

To gas: sublimation

From liquid…

To solid: freezing

To gas: vaporisation

From gas…

To solid: deposition

To liquid: condensation

To plasma: ionisation

From plasma to gas: recombination

Properties of water

Cohesion: how molecules stick together, e.g. via H-bonds, the stronger the cohesive bonds, the more the liquid will try to minimize surface area, sphere = minimize surface area

Water is polar, the molecules are attracted to each other,

Adhesion: water attracts other substances, overcome the adhesive forces, e.g. water and glass

Concave meniscus: water attracted to glass, polar + polar

Convex meniscus: mercury + glass, non-polar, minimize surface area

Surface Tension

Energy required to increase the surface area of a liquid

Depends on cohesive forces, water has high surface tension due to H bonds

Hydrogen bonds: weak bonds form and break continuously, strongest intermolecular force.

Capillary action

Process of a liquid flowing in a material because of cohesive and adhesive forces

Allows water and nutrients to be transported in plants

Due to both adhesive and cohesive forces

Viscosity

Resistance to flow

Water have low viscosity compared to honey

Increases viscosity:

Stronger intermolecular forces

Larger molecules

Lower temperatures