Chapter 14 Chemical Reactions

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Chapter 14 Chemical Reactions
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Forming New Substances

• ___________ -a process in which one or more
  substances change to make _____________________
  ______________
• The ________ and ________ _________of the new
  substance _______ from those of the original
  substances.
• Examples of chemical changes

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Signs of a Chemical Reaction

• formation of a solid ___________
• _____________- Solid substance that is formed in
  a solution

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Signs of a Chemical Reaction

• A change of properties
• The signs can help you identify a chemical
  reaction, but they do not guarantee a reaction
  took place.
• Ex. Boiling water gives off gas, but this is a
  physical change.
• The most important sign that a chemical change
  took place is the _______________
  ____________________________________.

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Chemical Bond

• _____________ -force that holds two atoms
  together in a molecule. The original bonds must
  _______ and new bonds must be ______.
• Ex 1 H2 and Cl2
• Chlorine gas has a greenish-yellow color
• Hydrogen gas is flammable
• Hydrogen chloride is a nonflammable, colorless
  gas.
• Ex 2 Na and Cl2
• Na is a metal that reacts violently with water
• Cl is a greenish-yellow poisonous gas
• Sodium chloride is a harmless substance that
  almost everyone uses.

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Ch 14.2 Chemical Formulas and Equations

• ______________ - a shorthand way to use
  ________________ and ___________ to represent a
  substance. It shows how many atoms of each kind
  are present in a molecule.

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Chemical Formulas and Equations

• Subscript- number written below and to the right
  of a chemical symbol in a formula.
• If no subscript is present, it means only 1 atom
  of that element is present.
• Ex H2O H O
• C6H12O6 C H O
• CO2 C O

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Writing formulas for Covalent Compounds

• composed of 2 nonmetals
• use prefixes
• if there is only one atom of the first element
• drop the mono- prefix
• change 2nd elements suffix to ide
• Ex CO2
• N2O

Mono- 1 Hexa- 6
Di- 2 Hepta- 7
Tri- 3 Octa- 8
Tetra- 4 Nona- 9
Penta- 5 Deca- 10
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Writing formulas for Ionic Compounds

• composed of a metal and a nonmetal
• put the metal first, nonmetal secondoverall
  charge must be 0.
• charges of the ions will cancel out
• criss-cross rule
• change suffix of nonmetal to ide
• Ex NaCl
• MgCl2

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Chemical Equations

• _______________ - chemical symbols and formulas
  as a shortcut to describe a chemical reaction
• ____________ - the starting materials in a
  chemical reaction
• ____________ -the substance formed from a
  reaction
• Ex C O2 ? CO2
• ?

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How do new substances form in a chemical reaction?

• 1.
• Molecules are always moving
• If molecules bump into each other with enough
  energy, the chemical bonds in the molecules
  break.
• 2.
• 3.

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The Reason Equations Must be Balanced

                                    

• Atoms are never ____ or _______ in a chemical
  reaction
• They are just _____________
• The of atoms in the __________ must __ of
  atoms in the ___________
• This is called balancing the reaction

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Law of Conservation of Mass

• ___________________ -Mass is neither created or
  destroyed in ordinary chemical and physical
  changes

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How to Balance an Equation

• You must use ___________- number placed in front
  of a chemical symbol or formula
• Ex 1 2CO means ____________________________
• Ex 2 2H2O means ___________________________
• Total there are __ hydrogen atoms and __oxygen
  atoms
• Only coefficients are changed when balancing
  equations ________________!!
• ___H2 ___O2 ? ___H2O

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Balancing Chemical Reactions

• ____ Na ____Cl2 ? ____NaCl
• Na Na
• O O
• ____ N2 _____ H2 ? ____ NH3
• N N
• H H

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14.3 Types of Reactions

                               

• _____________- A reaction in which two or more
  substances combine to form one new compound.
• A B AB
• Ex Sodium Chlorine Sodium Chloride

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Synthesis Reaction
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Types of Reactions

• ______________ -A reaction in which a single
  compound breaks down to form two or more simpler
  substances.
• AB A B
• Ex Carbonic Acid Water and carbon Dioxide

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Decomposition Reaction
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Types of Reactions

                                                            

                                                            

                                                            

                                                            

                                                         

• _______________________ - A single element
  replaces another element that is part of a
  compound.
• Products are a new compound and a different
  single element
• Ex
• The more reactive element can displace a less
  reactive element.
• Ex Copper can replace Silver, but the opposite
  cant occur.

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Single Replacement
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Types of Reactions

                                

• _____________________- A reaction in which ions
  from two compounds switch places.
• AB CD AD CB
• EX

• Sodium Chloride Silver Fluoride Sodium
  Fluoride Silver Chloride

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Double Replacement
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14.4 Energy and Rates of Chemical Reactions

                                   

                                   

• ________________________- Reaction in which
  energy is released.
• EXO means __________
• Ex 2Na Cl2 ?2NaCl ________
• ________________________ - Reaction in which
  energy is taken in
• ENDO means __________
• Ex 2H2O _________ ? 2H2 O2

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Law of Conservation of Energy

• _______________________________ - Energy cannot
  be created or destroyed
• Energy can be _____________ from one object to
  another
• _________________ - the speed at which new
  particles form
• __________________ - The smallest amount of
  energy that molecules need to react.

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Factors that Affect Reaction Rate

• _________________ the higher the temperature,
  the faster the reaction rate
• _________________- The higher the concentration
  of reactants, the faster the reaction rate
• ________________ - (amount of exposed surface on
  a substance) The larger the surface area, the
  faster the reaction rate
• ______________- A substance that slows down a
  reaction. Ex Preservatives in food slow down
  bacteria growth.
• ______________- A substance that speeds up a
  reaction without being permanently changed. NOT
  A REACTANT!! Ex Enzymes speed up reactions in
  your body.