Demo Time KI Decomposition of Hydrogen Peroxide 2H2O2  2H2O + O2 + HEAT!

Follow Up Questions Answer on a sheet of notebook paper: Describe what happened in this demonstration. Was this an endothermic or exothermic reaction? What was the catalyst in this reaction? What 2 products caused the dramatic “smoke”? 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: Describe what happened in this demonstration. What is a precipitate? 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 Tastes bitter feels slippery Turns red litmus paper blue 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 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 Put the litmus in the NaOH and in a baking soda solution. Then add the 2 together to do the neutralization and then test again.

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. Organic chemistry

Forming Polymers

Carbon Structures Polymers are mainly composed of various configurations of Carbon (C) & Hydrogen (H) Butane C4h10 (lighter fluid) BENZENE C6H6 (crude oil)

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)