Chemistry - The Scientific Universe

Energy

That which can do work

Units of energy

Units = Units of work = F x D = M x A x D = (kg m2)/s2 = Joule

Kinetic energy

• Energy due to motion

  • Macroscopic: KE = ½ mv2 (m is mass, v is velocity)

  • Microscopic: KE = 3/2 kT (k is Boltzmann constant, T is temp.)

Potential energy

• Energy due to position

  • Gravitational: PE = mgh (mass x acceleration x height)

  • Electrical: Coulomb’s Law = kq1q2/r2 (k is coulomb’s constant, q’s are magnitude of two points charges and r is the distance between them)

  • Chemical: Coulomb is HUGE for us

  • Nuclear

Matter

Anything that has mass & takes up space

Pure substance

• Composed of material that has a consistent, uniform composition

• Has a chemical formula, if none then it is not a pure substance

• Elements - composed of one type of atoms

• Compounds - composed of multiple types of atoms that are bonded together

Mixtures

• Variable composition

• 3 types

  • Solutions

  • Suspensions

  • Colloids

• Homogenous mixtures - has a uniform appearance

• Heterogenous mixtures - doesn’t have a uniform appearance

  • Ex: Pizza, burger, etc. (can differentiate ingredients)

Properties of solutions

• Heterogeneous or homogeneous? - homogenous

• Look: uniform and often clear

• Separate on standing? - will not settle on standing so will not need to be shaken or stirred

• Size of particles - small

• Separated by

  • Distillation, chromatography

Properties of Suspensions

• Heterogeneous or Homogeneous? - heterogenous

• Look: cloudy/chunky (should be able to determine the pieces in the solution)

• Separate on standing? - will separate on standing so will need to be shaken and stirred

  • Ex: Olive oil dressing

• Size of particles - Large

• Separated by

  • Manual

  • Decanting

  • Filtration

Properties of Colloids

• Heterogeneous or Homogeneous? - heterogeneous

• Look: may appear just slightly cloudy to clear

• Separate on standing? - does not separate on standing so does not need to be shaken or stored

• Size of particles - medium

• Separated by

  • Centrifuge

Test to determine a colloid from a solution

• Using the tyndil effect

  • Taking a beam of light and putting it in one side

  • If particles scatter then it is a colloid

The Essence of Chemistry

• Synthesis of new compounds

• Separation of mixtures

  • Manual separation

  • Decanting

  • Filtering

  • Distillation

  • Crystallization

  • Chromatography

• Identification

  • Based on physical properties

  • Based on chemical properties