Download Matter- Types and Changes

Matter
Types…And Changes
CHM 1010
PGCC
Barbara A. Gage
Matter
• Mixture – material with two or more
components with variable composition
• Solution – material with two or more
components homogeneously mixed; can have
variable proportions of the components
• Pure substance – material with a constant
chemical composition
Physical Separation Techniques
•
•
•
•
•
•
•
•
What property is each technique based on?
Dissolving
Evaporating (evaporation)
Filtering (filtration)
Chromatography
Sieving
Subliming (sublimation)
Distilling (distillation)
Extracting (extraction)
CHM 1010
PGCC
Barbara A. Gage
Types of Matter
• Element - the simplest type of substance with
unique physical and chemical properties. It
cannot be broken down into any simpler
substances by physical or chemical means.
• Compound - a substance composed of two or
more elements which are chemically
combined.
Figure 2.19
The distinction between mixtures and compounds.
Silberberg
S
Fe
Physically mixed therefore can be
separated by physical means; in this
case by a magnet.
Allowed to react chemically therefore
cannot be separated by physical
means.
CHM 1010
PGCC
Barbara A. Gage
Types of Matter
• Atom – smallest unit of an element with all
the characteristics of the element
Types of Matter
• Molecule - a structure that consists of two or
more atoms that are chemically bound
together and thus behaves as an independent
unit; smallest characteristic unit of a
compound that retains the properties of the
compound
Figure 2.1
Silberberg
The boxes here contain
submicroscopic views of
particles. Indicate
which box(es) contain
the stated item(s) and
why.
a.only elements
b.one compound
c.mixture of compounds
d.molecules
a.
b.
c.
d.
B, C, E
A (plus an element), D
F
All but E
Element Names and Symbols
• Each element has a name and 1, 2 or 3 letter
abbreviation called a symbol. The first letter
in a symbol MUST be capital and the other(s)
lowercase.
•
•
•
•
hydrogen
carbon
sodium
lead
H
C
Na
Pb
helium He
cobalt
Co
potassium K
mercury Hg
Image from WebElements
Element Names and Symbols
• Number of elements – 117 (#117 has not been
identified but 118 has)
CHM 1010
PGCC
Barbara A. Gage
Chemical Formulas
• Some elements appear in nature bonded to
each other. These are referred to as diatomic
or polyatomic molecules.
H2, O2, N2, F2, Cl2, Br2, I2
C60, S8, P4
• The 2 in O2 is termed a subscript and refers to
the element immediately in front of it.
Chemical Formulas
• CO2 contains 1 atom of carbon and two atoms
of oxygen all chemically linked.
• H2SO4 contains 2 hydrogen, 1 sulfur, and 4
oxygen atoms.
• (NH4)2C2O4 - A subscript outside parentheses
applies to everything within the parentheses;
2 N, 8 H, 2 C, 4 O
Chemical Formulas
• How many atoms of each type are in the
following compounds?
• K2CO3
• Ca3(PO4)2
• C6H4COOHCOC2H5
• AlK(SO4)2.12H2O
Chemical Reaction
• Chemical change = chemical reaction
Changes may be visible:
• color change
• cloudiness (precipitation)
• gas formed (bubbles and/or odor)
• reactant decreases (without dissolving)
• energy is released or absorbed
Chemical Equations
• Chemical changes can be written symbolically.
The symbolic representation is called a
chemical equation.
Carbon reacts with oxygen to form carbon
dioxide.
C + O2  CO2
reactants
products
Chemical Equations
• Reaction arrows can go in either direction:
2 H2 + O2  2 H2O
• Or both directions:
NH4OH
NH3 + H2O
Or…
Chemical Equations
• Because of the Law of Conservation of Matter,
you must account for all atoms in a chemical
change.
Carbon reacts with oxygen to form carbon
monoxide.
C + O2  CO
2 C + O2  2 CO
Equation is now balanced.
coefficient
Chemical Equations
• A sample of propane, C3H8, when ignited with
oxygen produces carbon dioxide and water.
O2 
C3H8
+
CO2 + H2O
C3H8
+ 5 O2  3 CO2 + 4 H2O
Chemical Equations
• Balance the following:
CaCl2 + Na2CO3  NaCl + CaCO3
C3H8O2 + O2  CO2 + H2O
H2SO4
+
KOH  K2SO4 + H2O
Chemical Equations
• If you have information on the states of
matter, that can be added to the equation.
s = solid l = liquid g = gas aq = aqueous
Aqueous silver nitrate reacts with aqueous
potassium chloride to form solid silver
chloride and aqueous potassium nitrate.
AgNO3 (aq) + KCl (aq)  AgCl (s) + KNO3 (aq)
Before
• Write the balanced
chemical equation for
the change in the
boxes and indicate the
reaction type.
After
Balancing Tips…
• Balance polyatomic ions (units) that stay intact
as a single unit.
• Leave hydrogens and oxygens to the last
(oxygen very last).
• Be sure to reduce the coefficients to the
smallest whole numbers.
Types of Reactions
• 1) Combination or Synthesis
• elements or (element + compound) or compounds
------> compound
•
Fe (s) +
S (s) ------> FeS (s)
•
O2 (g) + 2 CO (g) ------> 2 CO2 (g)
•
H2O (l) + SO3 (g) ------> H2SO4 (aq)
Types of Reactions
• 2) Decomposition or Analysis
• compound ------> elements or (element and
compound) or compounds
•
2 HgO (s) -----> 2Hg (l) + O2 (g)
•
2 KBrO3 (s) -----> 2 KBr (s) + 3 O2 (g)
•
CaCO3 (s) ------> CaO (s) + CO2 (g)
Types of Reactions
• 3) Single Replacement
•
element + compound -------->
element + compound
• Cu (s) + 2AgNO3 (aq) ---->2Ag (s) + Cu(NO3)2 (aq)
Types of Reactions
• 4) Double Replacement
compound + compound —> compound +compound
AgNO3 (aq) + NaCl (aq) —> AgCl (s) +NaNO3 (aq)
Double Replacement Rxns:
Solid forming
AgNO3 (aq) + NaCl (aq) —> AgCl (s) +NaNO3 (aq)
Gas-forming
KHCO3 (aq) + HCl (aq) ----> KCl (aq) + CO2 (g) +H2O (l)
Acid-Base
HCl (aq) + KOH (aq) ----> KCl (aq) + H2O (l)
Types of Reactions
• 5) Oxidation-Reduction (redox)
CH4 (g) + 2O2 (g) ----> CO2 (g) + 2H2O (l)
2Mg (s) + O2 (g) -----------> 2MgO (s)
4HCl (aq) + 3FeCl2 (aq) + KMnO4(aq) -->
MnO2(s) + KCl(aq) + 3FeCl3(aq) + 2H2O(l)
Investigation of Chemical Reactions
• Let’s finish the lab by writing the balanced
chemical equations and determining the
types:
• Mg + HCl
• Mg (heat)
• CoCl2 + Na3PO4
• Fe + CuSO4
• KClO3 (heat)
• CuCO3 (heat)