Science 11

• Molar Mass:

  • Defined as the mass of one mole of atoms, molecules, or formula units of a substance
  • Numerically equal to the atomic mass, molecular mass, or formula mass of a substance
  • Expressed in gram per mole (g/mol)
• Using Avogadro’s number and the molar mass, one can calculate the mass in grams of one carbon-12 atom

  • Relationship: 1 mol = 6.022 x 10^23 C-12 atoms = 12 g C-12
  • Conversion factors: 1 mol C-12 atoms = 6.022 x 10^23 C-12 atoms = 12 g C-12
• Determining Significant Figures:

  • Rules for Multiplication and Division
  • Rules for Addition and Subtraction
• • 0.024 mol Na2CO3 x 6.022 x 10^23 formula units Na2CO3 / 1 mol Na2CO3 = 1.4 x 10^22 formula units Na2CO3
• Sample problem:

  • Calculate the number of moles and formula units in 2.5 g of soda ash (Na2CO3)
  • Given: mass of Na2CO3 = 2.5 g
  • Find: moles of Na2CO3 = ?, formula units of Na2CO3 = ?
  • Calculate the formula mass of Na2CO3:
  • Na: 2 moles, 22.99 amu, product = 45.98
  • C: 1 mole, 12.01 amu, product = 12.01
  • O: 3 moles, 16.00 amu, product = 48.00
  • Total = 105.99 g/mol
  • Find the moles of Na2CO3:
  • 2.5 g Na2CO3 x 1 mol Na2CO3 / 105.99 g Na2CO3 = 0.024 mol Na2CO3
  • Find the formula units of Na2CO3:
• Determine the molar mass of K3PO4:

  • K: 3 moles, 39.10 amu, total mass = 117.3 g/mol
  • P: 1 mole, 30.97 amu, total mass = 30.97 g/mol
  • O: 4 moles, 16.00 amu, total mass = 64.00 g/mol
  • K3PO4 molar mass = 212.27 g/mol
  • Final answer: 212.3 g/mol
• Stoichiometry is about measuring the amounts of elements and compounds involved in a reaction
• When N2O5 is heated, it decomposes to form 4 NO2 and O2
• When 4.3 moles of N2O5 are used:

  • 8.6 moles of NO2 can be produced
  • 2.2 moles of O2 can be produced
• When 2.00 moles of O2 are used:

  • 6 moles of H2O are produced
• When 15 moles of H2O are produced:

  • 10 moles of NO are produced
• When 5.17 grams of Fe(C5H5)2 are used:

  • 0.0278 moles of Fe(C5H5)2 are produced
• When 23.9 grams of H2O are reacted:

  • 0.442 moles of Al2O3 are produced
• When 2.20 moles of NH3 are used:

  • 59.5 grams of H2O are produced
• When 0.3 moles of H2O are produced:

  • 8 grams of O2 are required
• When 210 grams of NO2 are produced:

  • 2.28 moles of N2O5 were used
• When 75.0 grams of O2 are produced:

  • 506.3 grams of N2O5 are needed
• When 3.45 grams of Al are reacted:

  • 17.0 grams of AlCl3 are produced
• When 12 grams of O2 are used:

  • 30.01 grams of NO are produced
• Chemical Thermodynamics deals with the transformation of energy involved in a chemical reaction
• Fusion and fission are mentioned
• Endothermic reactions: Products contain a greater amount of energy than the reactants
• Exothermic reactions: Products contain a lesser amount of energy than the reactants
• Enthalpy Change: Amount of heat evolved or absorbed in a reaction
• Nonrenewable resources take too long to replace or cannot be replaced at all
• Renewable resources can be made again by nature or by people in a practical amount of time
• Fossil fuels:

  • Coal:
  • A sedimentary rock composed predominantly of solid organic materials with a greater or lesser proportion of mineral matter
  • Has the largest reserve and is often the cheapest of the fuel options
  • Obtained by mining (strip and subsurface)
  • Burned in power stations to make electricity and a source of heat
  • Advantages:
  • Abundant
  • Lower capital investment
  • High load factor
  • Can be made clean
  • Disadvantages:
  • Nonrenewable
  • Transporting is costly
  • SOx and NOx
  • Health risks
  • Oil/Petroleum:
  • Dark liquid fossil fuel formed by hydrocarbons
• • Mainly used in transportation as fuel for cars, trucks, boats, and other forms of transportation
  • Advantages:
  • Easy to handle, store and transport
  • Easier to extract than coal
  • Technology and infrastructures are established
  • Disadvantages:
  • Requires refining
  • May affect natural habitats
  • Emits CO2
  • Harnessing poses spill threat
  • Natural Gas:
  • Classified as hydrocarbons (C & H)
  • Located above coal and oil deposits
  • Colorless, shapeless, and odorless in its pure form
  • Advantages:
  • Abundant
  • Burns efficiently
  • Cleanest of all fossil fuels
  • Compressed Natural Gas (CNG)
• • Disadvantages:
  • Nonrenewable
  • Emits CO2
  • Potent greenhouse gas
  • Long distance pipelines
  • Potential explosive
• Nuclear Energy:

  • Nuclear power plants harness energy through Nuclear Fission
  • Requires much higher temperature but produces much more energy per amount
  • Uses Uranium-235 and a bombardment of neutron
  • How is electricity produced?
  • Advantages
  • Disadvantages
  • Chernobyl Incident
  • Bataan Nuclear Power Plant
• • Limitless
  • Disadvantages:
  • Small land area
  • Health hazards
  • Lot of water
  • High construction cost
  • Long distance transmission
  • Earthquake
  • Biomass:
  • Biological material derived from living or recently living organisms
  • Advantages:
  • Renewable and nonpolluting
  • Clean surroundings
  • Healthy disposal of waste
  • Disadvantages:
  • Cheap
  • Small scale application
  • Large scale application
  • Low efficiency
  • Corrosive to engine materials
  • Not applicable in several locations
  • Wind:
  • Result of heating of earth’s surface due to solar energy
  • Advantages:
  • No air pollutants
• Renewable Resources:

  • Hydroelectric Power:
  • Electricity generated using the energy of moving water
  • The first hydroelectric power plant was built at Niagara Falls in 1879
  • Provides almost one-fifth of the world's electricity
  • Advantages:
  • Renewable
  • Clean
  • Flexible
  • Irrigation
  • Disadvantages:
  • Change ecosystem
  • Expensive
  • Drought
  • Relocation of communities
  • Geothermal Energy:
  • Heat from the Earth’s crust
  • The world’s first geothermal power plant was constructed in 1904 in Larderello, Italy
  • Advantages:
  • Less air pollution (CO)
  • Zero carbon emission
  • Simple and reliable
• • Free and abundant
  • Cost-effective
  • Land used can be maximized
  • Disadvantages:
  • Noise pollution
  • Not constant
  • High initial cost
  • Impact on wildlife (birds and bats)
  • Solar Energy:
  • Radiant light and heat from the sun harnessed using a range of technologies
  • Produces less than one-tenth of one percent of global energy demand
  • Advantages:
  • Renewable
  • Safe
  • Little maintenance
  • No noise pollution
  • Disadvantages:
  • Expensive (silicon)
  • Availability
  • Efficiency is low
  • Requires inverter for AC production
  • Requires energy storage
  • Large area for solar power stations
• Detergents are synthetic, water-soluble cleansing agents with wetting and emulsifying properties
• Detergents contain sodium salts of strong acids derived from petroleum and coal
• The cleansing power of detergent is better than soap and water alone because:

  • Detergent is not prepared from fats and oil
  • Detergent is not inactivated by hard water
• Detergents have two essential components with a polar head and a nonpolar tail
• To increase the cleaning ability of water, the surface tension must be reduced using a surfactant
• Surfactants have the ability to form micelles which trap dirt and hold grease
• Trapped grease or dirt is a salt composed of sodium or potassium ions paired with long hydrocarbon chain fatty acids