Transcript chemi-unit-part

Demo Time
Decomposition of
Hydrogen Peroxide
KI
2H2O2  2H2O + O2 + HEAT!
Follow Up Questions
Answer on a sheet of notebook paper:
1. Describe what happened in this
demonstration.
2. Was this an endothermic or
exothermic reaction?
3. What was the catalyst in this
reaction?
4. What 2 products caused the
dramatic “smoke”?
5. What type of reaction is this?
Synthesis, decomposition or replacement
Precipitate Reactions
If the ions in 2 solutions combine to
form a solid and that solid is NOT
soluble with the solvent produced a
precipitate will form.
 Example
Fe(NO3)3(aq) + 3 NaOH(aq) 
Fe(OH)3(s) + 3 NaNO3(aq)
Demo Time
Cu(NO3)2(aq) + 2 NaOH(aq) 
Cu(OH)2(s) + 2 NaNO3(aq)
Follow Up Questions
Answer on a sheet of notebook
paper:
1. Describe what happened in
this demonstration.
2. What is a precipitate?
3. What type of reaction is
this?
Synthesis, decomposition or replacement
Balancing Equations
All atoms of
reactants must be
account for after
the reaction!
Acids
Produce H+ ions in H2O
Ex: HCl  H+ + ClProperties:
•Tastes sour
• Corrosive reaction w/metal
• Reacts w/CO32- to make CO2
• Turns blue litmus paper red
Examples of Acids
• HCl – hydrochloric acid
• CH3CO2H – acetic acid (vinegar)
• H2SO4 – sulfuric acid
• Ascorbic Acid – Vitamin C (citrus)
• Fertilizers –
Nitric & Phosphoric Acid
• Lactic Acid
Bases
Produce OH- ions in H2O
Ex: NH3 + H2O  NH4+ + OH-
•Tastes bitter
• feels slippery
• Turns red litmus paper blue
Examples of Bases
•
•
•
•
NaHCO3 – baking soda
household cleaners including:
NH3- ammonia
Drain Cleaner
Strength
The strength of an acid or a base
is based on how well it produces
ions in water.
Strong Acids – HCl & H2SO4
Strong Bases - NaOH
Measuring Strength
pH = Potential Hydrogen
Range of values from 0 to 14 that
describes the concentration of H+
ions in a substance.
Safety
Know the pH (strength) of the
acid or base you are handling.
Everything from 2-12 is in the
safe zone.
Precautions
When working with a strong acid
or base (0-2 or 11-14) be sure to
wear goggles…even if it’s a dilute
solution!
For spillsPour vinegar on a base & sodium
bicarbonate on an
acid…because…
Acid Base Neutralization
Displacement reaction
Acid + Base 
(liquid) water +(solid) salt
Salt = Group 1-2 Metal + a
halogen
Demo Time
NaHCO3 + NaOH  Na2CO3 + H2O
Chemicals Everywhere
Chemistry all around us:
• Beauty products
• Cleaning products
• Food products
• Scents & flavors
• Monitoring the environment
• Containers
• Protection
• Explosives
Materials
We use the following materials on
a regular basis, they are made of
various substances that we’ve been
studying lately:
• Plastics
• Metals
• Alloys
• Ceramics
• Glass
Chemistry Around Us
•
•
•
•
•
•
•
•
•
Beauty products
Cleaning products
Food products
Scents & flavors
Monitoring the environment
Containers
Protection
Explosives
Fuels
Polymers
Large complex molecules made
from smaller molecules joined
together in a repeating pattern
(chain).
They are both naturally
occurring & synthetic.
Forming Polymers
Carbon Structures
Polymers are mainly composed
of various configurations of
Carbon (C) & Hydrogen (H)
Natural Polymers
• Cellulose – cell walls of fruits &
vegetables
• Starches – pasta, bread &
vegetables
• Natural fibers – hair, wool
• Amino Acids  Protein DNA!
Synthetic Polymers
•
•
•
•
Plastics
MANY types (see p.731)
Fibers – carpets, nylon
Chewing gum
Teflon coating
Plastics
Benefits:
• Cheap & easy to make
• Lightweight
• Versatile
• Durable
Problems:
• Disposal
Recycling is cost prohibitive 
Alloys
A mixture of 2 or more
elements at least one of which
is a metal.
Alloys are usually stronger &
more durable than the metals
which they are made from.
They are also less likely to
suffer corrosion from oxidation.
Examples
•
•
•
•
•
Sterling silver – Ag & Cu
Gold – Au &/or Cu
Pewter – Sn, Sb, Cu, Pb*
Brass – Cu, Zn
Steel – Fe, Cr, Ni, C
Ceramics
Hard, crystalline solids made
from heating clay (water &
minerals – Si, AL & O) to very
high temperatures.
Properties
• Water resistant
• Strong building material bricks
• Not conductive of electricity
• Can withstand much higher
temperatures than most
metals
• Brittle & prone to breaking
Uses
•
•
•
•
Containers
Storage
Cookware
Archaeologists use ceramic
sherds for relative dating!
• Home construction – roofs &
floors
• Replace joints – hips, knees,
teeth (dentures)
Glass
Molten sand & limestone can
be shaped and cooled into
waterproof vessels.
Uses
•
•
•
•
Storage
Containers
Windows
Lenses for eyeglasses,
telescopes, microscopes
• Cookware
• Data transmission (optical
fiber)