Transcript Chemical Reactions

Chem G
Review
 Chemistry is the study of matter and the changes it
undergoes.
 Matter is anything that has mass &
volume
 Changes can be
 Physical: melting, freezing, evaporating
 Chemical: neutralization, combustion
Chemical Reactions
 Chemical reactions are in the form of:
Reactant + Reactant  Product + Product
What other symbols are included in a
chemical reaction? (page 206)
Write the following chemical
reactions:
 Sulfur burns in oxygen to form sulfur
dioxide.
 Sodium metal and water form sodium
hydroxide and hydrogen gas
Why H2?

Diatomic elements: HONCl BrIF
 These elements are never found alone.
Always in combination with other
atom even if just another of its own
kind.
 Example:
oxygen = O2
Types of Chemical Reactions
 Combination (synthesis) Reactions
 Two or more substances combine to
form a single substance
 Example: SO3 + H2O  H2SO4
 Calcium
oxide and water form
calcium hydroxide
Types of Chemical Reactions
 Decomposition reactions
 A single compound is broken into
two or more compounds
 Example:
 Calcium carbonate is heated and
decomposes into calcium oxide and
carbon dioxide
Types of Chemical Reactions
 Single-Replacement (displacement)
 One element replaces another in a
compound
 Example: Mg + ZnCl2  Zn + MgCl2

Calcium oxide reacts with aluminum metal
Types of Chemical Reactions
 Double Replacement (displacement)
Reactions
 An exchange of the positive and negative
ions in each compound
 Example: MgCl2 + Li2O  MgO +
LiCl
 Barium chloride and potassium
fluoride form the compounds barium
fluoride and potassium chloride
Types of Chemical Reactions
 Combustion Reactions
 What do you remember about this type of reaction?
 _________ + __________ _________ + _________
Chemical Reaction of Solutions
 Solution - two or more substances
physically combined that appear
uniform throughout.
 Solutions are composed of:
solvent - substance into which the
solutes are dissolved
solutes - substances being
dissolved.
Solvent/ Solute combinations
 Solids
 solid/solid
alloys (Ni and Pt into Au)
 liquid/solid
amalgam fillings (Hg into Ag)
 gas/solid
CO into Pt or Pd
Solvent/ Solute combinations
 Liquids
 solid/liquid
Kool Aid (sugar into water)
 liquid/liquid
paint in paint thinner
 gas/liquid
carbon dioxide into pop
Solvent/ Solute Combinations
 Gases
 solid/gas
Food odors into the air
 liquid/gas
perfume into the air
 gas/gas
oxygen into the air
The Solubility Rules for Water
 1. All common salts of lithium, sodium, potassium, and




ammonium are soluble.
2. All common salts of nitrates, acetates, chlorates, and
perchlorates are soluble.
3. All common salts of chlorides, bromides, and iodides
are soluble, EXCEPT for those of Ag, Pb(II), and Hg(I).
4. All common salts of sulfates are soluble, EXCEPT for
those of Pb(II), Ca, Sr, and Ba.
5. All common salts of carbonates, phosphates,
hydroxides and sulfide are insoluble, EXCEPT for those
listed in rule 1.
Sample Compounds
 lithium chloride
_____
 iron (III) phosphate _____
 magnesium chloride _____
 ammonium sulfate _____
 sodium carbonate _____
Sample Compounds
 lithium chlorate
 _S(1)or(2)_
 iron (III) phosphate  _I(5)_
 _S(3)_
 magnesium
chloride
 _S(1)or(4)_
 ammonium sulfate  _S(1)or(5)_
 sodium carbonate
Sample Compounds
Ba(NO3)2 _________
Na3(PO4) _________
BaCl2
Ca(SO4)
Fe(CO3)
_________
_________
_________
Sample Compounds
 Ba(NO3)2
 _soluble (2)
 Li3(PO4)
 _soluble (1)
 BaCl2
 _soluble (3)
 Ca(SO4)
 _insoluble (4)
 Fe(CO3)
 _insoluble (5)
Polar and Non-Polar
Polar molecules have a
definite positive and
negative end. (water,
ionics, alcohols)
Non-polar molecules
have uniform external
charge
General Rule to Solutions
Like solvents dissolve
like solutes,
and unlike solvents
will not.
(Like dissolves like)
Freezing Point Depression
What is the science behind
putting salt on the roads in
the winter?
Polar and Non-Polar
Some molecules are large
enough to have both polar
and non-polar
characteristics. Soap
molecules are an
excellent example of a
bipolar particle
Solubility and Saturation
Is there a limit to the amount of
salt that will dissolve in to a certain
amount of water?
Yes?? No?? Explain
Solubility and Saturation
The solute will continue to
dissolve until the solution is full
of solute:
 Saturated-as much as possible
 Unsaturated -less than possible
 Supersaturated-more than possible
Solubility and Saturation
Dissolving can be aided in
three ways:
 1. ______________
 2. ______________
 3. ______________
General Rule to solubility
 If only a little solute will
dissolve in a lot solvent, the
solute is said to be insoluble.
 If only a lot solute will
dissolve in a little solvent, the
solute is said to be soluble.