SCIENCE 4TH Quarter Reviewer

• Gas - has no definite shape. When we vary their temperature and pressure, their behavior can easily predicted.
• Compressibility - gas has large intermolecular spaces in the midst of them. Greater volume lower pressure-less volume higher pressure. Implies a decrease in volume
• Expansibility - when pressure exerted, gas contracts. When pressure freeds gas expands. Gas expand when heated and contract when cooled. Temperature increased-volume increase.
• Diffusibility - allows gas particles to spread out and fill any container unlike liquid or solid. Ability to spread from higher concentration to lower concentration.
• Liquefaction - gases liquefy when sufficiently cooled.
• Low density - have huge intermolecular spaces large volume
• Kinetic molecular theory -possess negligible mass and volume; move at high speed and straight path in random direction- collide against each other or walls- perfectly elastic; neither attractive nor repulsive force; and velocity changes with temperature   
• Gay-lussac's law - Joseph Louis Gay-Lussac (1778-1850). Pressure and temperature. P1T2=P2T1. Examples are pressure cooker and aerosol spray. Directly proportional
• Charles law - Jacques Alexander-Cesar Charles (Nov 12, 1746- April 7. 1823), french mathematician and physicist. Volume and temperature. V1T2=V2T1. Directly proportional. Examples are tires, helium balloons, pool floats, deo spray bottles
• Ideal gas law - Benoit Paul Émilé Clapeyron (1799-1864), physicist and engineer. Negligible volume, do not have intermolecular forces (attraction or repulsion), and particles move randomly. Discovered in 1834. PV=nRT. R= 0.0821 L•atm/mol•k. Example is airplanes
• Chemical change


  A process that leads to the chemical transformation of one set of chemical substances to another. Change of substance into different substance with different properties. Change occurs when bond broken and/are formed between molecules or atoms. Changes the composition of the original substances. Produce new substances.
• Indicators of chemical change


  • Temperature changes
  • Unexpected color changes
  • Light given off
  • Solid forms if two clear liquids are mixed
  • Bubbles are formed
  • Different smell
  • Energy is released
• Physical change - any change in substance is formed that does not change its chemical makeup. Visible change, no bonds are broken or formed, involve moving molecules around but not changing them. Indicators of physical change are change in state, physical deformation, and change is temporary/reversible
• Reactants - substances that go into a chemical reaction
• Products - produce at the end of the reaction
• Chemical equation - chemist shorthand for chemical reaction, indicating the reactants and products in reaction and the direction
• Jean Beguin - french chemist credit for formulating first chemical equation in 1615
• Reaction arrow - tells which the chemical reaction proceeds
• Types of chemical reaction

  • Combination
  • Decomposition
  • Single displacement
  • Double displacement
  • Combustion
  • Acid base
• Combination


  2 or more reactants combined to form single product
• Decomposition


  1 reactant to produce 2 or more products
• Single displacement


  One element replaces another element from a compound
• Double displacement


  Positive ions (cation) and negative ions (anion) of different compounds exchange places forming two different compounds
• Combustion


  Oxygen combines with hydrocarbon to form water and carbon dioxide (carbon and hydrogen)
• Acid base


  Special kind of double displacement reaction that takes place when an acid and base react with each other forming water and salt
• Balance chemical equation - the number of each type of atom is equal on the two sides of the equation.
• Law of conservation of mass - the total mass of the reactants is equal to the total mass of the product
• Steps in balancing chemical equation

  1. Take notes of elements
  2. Count the number of atoms
  3. Apply the law of conservation of mass to get same number of atoms on each side of the equation. Do not change the subscripts
• Collision theory - explains how collision between reactants molecules may or may not result in a successful chemical reaction
• Effective collision - a. Colliding molecules should process a minimum kinetic energy known as activation energy to start a chemical reaction. b. Reactants molecules should be in correct orientation when they collide
• Factors affecting the rate of chemical reaction

  • Temperature
  • Surface area of reactants
  • Catalyst
  • Concentration of reactants
• Temperature


  Increasing the temperature increases the rate of chemical reaction. The higher the temperature, the higher the kinetic energy of particles, the more they collide.
• Surface area of reactants


  The smaller the size of a particle, the greater the surface area. Increasing the surface area speeds of the rate of reaction by increasing the collision rate.
• Catalyst


  A substance that increases the rate of reaction.
• Inhibitor


  A substance that slows down or inhibits reaction rates.
• Concentration of reactants


  Increasing the concentration of reactants, increases the rate of reaction. The more particles present, the more often they collide.
• Effects of chemical reaction

  1. Acid rain
  2. Formation of ozone layer in the atmosphere
  3. Car airbag
  4. Photochemical smog
  5. Fire control - a. Ordinary combustibles, b. Flammable liquid or gases, c. Electrical equipment and d. Flammable metals
  6. Corrosion control
  7. Food processing and prevention
• Biomolecules - "biological molecule". Substances that are produced by cell and living organisms. Have a wide range of sizes and structures and perform of us array of functions
• Carbohydrates


  Chief source of energy
• Monosaccharides


  Mono means one and saccharide means sugar. Consists of one sugar. Simplest form of sugar and basic unit of carbohydrates. Usually colorless and very soluble in water