demo time decomposition of hydrogen peroxide ki 2h 2 o 2 2h 2 o + o 2 + heat!

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+ + Cl-

Properties:•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.

PrecautionsWhen 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 spills-Pour 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• DurableProblems:• 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)