Chemical vs physical properties

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Chemical vs physical properties
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Elements and compounds can be described by their
chemical and physical properties

• Physical property characteristic of a substance
  you can observe (using your senses) without
  changing it into something else
• State of matter (solid, liquid, gas)
• Melting, freezing, boiling point
• Magnetism
• Density
• Color
• Shape
• Malleability
• Solubility
• Specific heat

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• Chemical properties properties of an element or
  compound in a chemical reaction
• pH
• Reactivity
• Flammability/Combustion
• Rusting
• Bond

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• Practice on Identifying Chemical and Physical
  Properties
• Water boils at 100 degrees Celsius.
• Diamonds are capable of cutting glass.
• Water can be separated by electrolysis into
  hydrogen and oxygen.
• Sugar is capable of dissolving in water.
• Vinegar will react with baking soda.
• Yeast acts on sugar to form carbon dioxide and
  ethanol.
• Wood is flammable.
• Aluminum has a low density.
• Ammonia is a gas at room temperature.
• Bromine has a red color.

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• Which of the following conclusions can be drawn
  from the information shown?
• Most types of matter heat up at the same rate
• Most types of matter cool at the same rate
• It takes less energy to heat 1g of silver than 1g
  of gold
• It takes more energy to heat 1g of water than 1g
  of copper

Material Specific Heat
Aluminum 0.899
Copper 0.387
Gold 0.129
Silver 0.234
Water 4.182
Wood 0.176
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• Magnesium melts at 650C. If a 100g sample of
  magnesium melts at 650C, then a 75g sample would
  melt at
• 325C
• 650C
• 487.5C
• 162.5C

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• Chemical change atoms are rearranged, I have
  different substances at the end of a chemical
  reaction/change
• Change in color
• Formation of precipitate (LL?S)
• Formation of a gas
• Creation of light
• Burning
• Change in temperature (exothermic, endothermic)

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Changes can be physical or chemical

• Physical changes do not rearrange atoms, I have
  the same substance I started with. I can reverse
  a physical change
• Change in shape
• Change in phase
• Dissolving
• Reversable

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• Practice on Identifying Chemical and Physical
  Changes
• Dry ice, solid carbon dioxide, is sublimed at
  room temperature.
• Salt is dissolved in water.
• Iron rusts in a damp environment.
• Gasoline burns in the presence of oxygen.
• Hydrogen peroxide decomposes to water and oxygen.
  

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Combustion reacting with oxygenfrequently
producting CO2 water

• C3OH O2 ? CO2 H2O heat
• 2Mg O2 ? 2MgO Heat
• ______________________________________
• 2H2 O2 ? 2H2O heat
• NH4 NO2 ? N2O H2O

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Compounds or molecules are represented using a
chemical formula

• 4CO2
• Subscripts (little number) tell you the number of
  atoms in the 1 molecule of the compound
• Coefficients (big number out front) tell you how
  many molecules
• (no number means the number is 1!)

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Calculate the number of atoms of each element

• AgMnO4
• AlBO2
• CH3OH
• BaSi2O5

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Calculate the total number of atoms of each
element

• 2AgMnO4
• 6AlBO2
• 7CH3OH
• 2BaSi2O5
• KNO3

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Conservation of Mass

• Mass on the reactant side of the equation equals
  the mass on the product side of the equation
• Number and type of atoms on the reactant side of
  the equation equals the number and type of atoms
  on the product side of the equation.
• Reactants
  Products

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• To check for balance, multiply coefficient x
  subscript
• __H2 __O2 ? __H2O
• A. 1, 1, 1
• B. 2, 1, 2
• C. 2, 1, 2
• D. 2, 2, 2
• __K __B2O3 ? __K2O __B
• A. 3, 2, 3, 2
• B. 6, 1, 3, 2
• C. 6, 2, 3, 2
• 3, 2, 2, 2
• To balance an equation its cool to change
  coefficients, do not change subscripts.dont
  mess w/the little people (youll change the
  molecules identity!)

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• Calculate the mass of the product of 6.40 g of
  magnesium with 1.32 g of oxygen .
• Calculate the mass of the zinc that reacts with
  4.11 g of hydrochloric acid to form 9.1 g of zinc
  chloride and 3.97 g of hydrogen gas.
• During the combustion of 5.00 g of Butane in the
  presence of oxygen, 4.01 g of carbon dioxide and
  3.55 g of water is given off. How much oxygen was
  needed to totally combust the butane?

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Review..
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Compound

• Made when two or more elements combine during a
  chemical reaction
• Examples
• Water
• Salt
• Sugar
• Chemical Change

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Compounds are formed or separated through
chemical reactions

• What is evidence that a chemical reaction is
  happening again?
• Fire, Combustion, Explosion
• A new color appears/disappears
• Temperature change
• Production of Gas, gas bubbles
• Production of Precipitates

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Mixture

• Combines 2 or more substances without producing a
  chemical reaction
• NOT the same throughout - heterogeneous
• Can be separated easily
• Examples
• Soil
• Fruit salad
• Physical Change

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Solution

• A type of MIXTURE that IS the same throughout
• - homogenous
• Solute- substance being dissolved
• Solvent- substance doing the dissolving
• Examples
• Salt water
• Lemonade
• Physical Change

Salt Solute
Water Solvent
Salt Water Solution