Chemistry

• Bases are substances that release hydroxide ions when dissolved in water.
• Kinetic Molecular Theory (KMT)

  A model used to explain the behavior of matter
• States of matter

  • Solid
  • Liquid
  • Gas
• Postulates of KMT

  • Matter is made of particles that are constantly in motion
  • The amount of kinetic energy in a substance is related to its temperature
  • In solids and liquids, liquid particles have more kinetic energy since they can freely flow
  • There is space between particles, the amount of which is related to the substance's state of matter
  • Phase changes happen when the temperature of the substance changes sufficiently
  • Attractive forces between particles are called intermolecular forces, and the strength increases as particles get closer together
• Difference between condensed states (liquids and solids) and gaseous state

  Distance between molecules
• Solid

  Molecules are held rigidly in position with virtually no freedom of motion, less space than in liquids, almost incompressible, possess definite shape and volume
• Liquid

  Molecules can move past one another freely, can flow, can be poured, and assume the shape of their container, definite volume, molecules held together by attractive forces
• A solid, molecules are held rigidly in position with virtually no freedom of motion. There is even less space in a solid than in a liquid. Solids are almost incompressible and possess definite shape and volume.
• A liquid also has a definite volume. The molecules can move past one another freely, can flow, can be poured, and assume the shape of their container. Molecules in a liquid are held together by one or more types of attractive forces
• Surface Tension

  The force that causes the molecules on the surface of a liquid to be pushed together and form a layer
• Surface Tension

  • The strength depends on the intermolecular force of attraction
  • It is a force that causes the surface of a liquid to contract
  • The imbalance of forces at the surface of a liquid gives rise to surface tension
• Surface Tension

  • The paper clip remains suspended on the surface of the liquid because of the intermolecular forces attraction
• Intermolecular force of attraction

  The stronger the force, the greater the surface tension
• Temperature

  An increase in temperature decreases surface tension
• Viscosity

  A liquid's resistance to flow that exists between molecules when they move past each other
• Intermolecular force of attraction

  The difference between two liquids' viscosity is a measure of their intermolecular force of attraction
• Intermolecular forces

  The greater the h-bonds, the stronger the IMF, the higher the viscosity
• Temperature

  Heat breaks the intermolecular forces causing the liquid molecules to move faster, allowing freer movement
• Vaporization

  The change of state from liquid to gas
• Evaporation

  When liquid molecules break free from their neighbors and escape into the gas phase
• Vapor pressure

  The pressure exerted by the vapor in equilibrium at a given temperature in a closed system
• Temperature

  Vapor pressure is affected by the temperature in a closed system
• Vaporization process

  Molecules in constant motion collide, and some leave the liquid phase as vapor
• Factors affecting vaporization rate

  • Surface area
  • Temperature
  • Intermolecular forces
• Intermolecular forces

  The weaker the forces, the faster the vaporization
• Substances that evaporate readily are volatile, with weaker intermolecular forces
• Condensation process

  Some vapor molecules lose kinetic energy, are trapped by attractive forces, and return as liquid molecules
• Temperature

  The kinetic energy of liquid molecules depends on temperature
• Temperature

  If temperature increases, vapor molecules increase, and vapor pressure increases
• Intermolecular forces

  Stronger IMF = lower evaporation rate = lower vapor pressure; weaker IMF = higher evaporation rate = higher vapor pressure
• Boiling point

  The temperature at which a substance transitions from liquid to gaseous state, when the vapor pressure equals atmospheric pressure
• Boiling process

  Small bubbles begin to rise as temperature increases, and the heat added equals the heat escaping through evaporation
• Atmospheric pressure

  The lower the pressure, the faster the liquid's vapor pressure equalizes, and the lower the boiling point
• Vapor pressure

  Liquids with high vapor pressure have low boiling points
• Intermolecular forces

  Liquids with weak IMF have high vapor pressure and low boiling points; liquids with strong IMF have low vapor pressure and high boiling points
• The difference between vaporization and boiling is that vaporization is the change from liquid to gas, while boiling is the temperature at which this transition occurs
• Water is a universal solvent with the ability to dissolve a large variety of chemical substances
• Water's unique properties

  Result from the strong intermolecular forces of attraction characterized by the hydrogen bond
• Properties of Water

  • High Boiling Point
  • High Specific Heat
  • High density in Liquid form
  • High Surface Tension
  • High Heat of vaporization
• High Boiling Point

  A consequence of water's strong intermolecular forces of attraction caused by the formation of hydrogen bonds