CH 302 - Exam 3 Review Facts

Boron

• usually forms only three covalent bonds (contrary to the octet rule)

• found in boric acid which is used to kill ants

• found in borax which is used as detergent

nitrogen

• can assume many oxidation states (from -3 to +5)

• found in explosives, fertilizers, and as an oxide in laughing gas, Viagra, smog, and preservatives

• made with the Haber process from H2 and N2 at low temperatures

carbon

• has three allotropes

  • C60 - forms interesting tubular + spherical structure

  • Graphite - sp2 hybrodized

  • Diamond - sp3 hybrodized

  • CO3- - inorganic form of carbon that is an essential partof the cycle involving greenhouse gas

  • CO2 - a diprotic acid

  • CaCO3 - limestone

phosphorous

• found in soaps, toothpaste, fertilizer, and pesticides

• Is extracted from Ca3(PO4)2 rock

• Phosphate is the backbone of nucleic acids like DNA

• Phosphates cause algae to bloom which means their use is discouraged for environmental reasons

halides

• have small radii, high ionozation energy, high electronegativity, and form -1 anions

• oxides and hydrides are acidic

fluoride

• F- inserts instead of OH- in tooth enamel to protect from decay

Chlorine

• manufactured as Cl2, a strong oxidizing agent

• used in disinfection and sanitation

• used to make PVC tubing

noble gases

• inert with 2 or 8 electrons in filled shells

• specialty uses include Cryogens (He), inert gases (Ar), and lights (Ne)

Wet Method

• produces H3PO4 (phosphoic acid)

Claus Process

a two step oxidation produces elemental sulfur from H2S, which is contaminant in natural gas, methane

Contact Process

A four step oxidation process that produces H2SO4 from elemental sulfur, S

claus + contact processes

combine to produce H2SO4 through a series of oxidation and acid/base reactions

Sulfuric acid

• is the most manufactured chemical in the world

• about half of all sulfuric acid is used to solubilize phosphate in rocks by the wet method (the solubilized phosphate is used in fertilizers)

• it is also a strong oxidizing agent and a strong dehydration agent

Batteries (aka voltaic/galvanic cells)

• Delta G is negative

• K is greater than 1

• E is positive

• Reduction occurs at the cathode

• Oxidation occurs at he anode

• e- flow Anode to Cathode

• The sign of the cathode is positive

• the sign of the anode is negative

Electrolytic cells

• Delta G is positive

• K is less than 1

• E is negative

• Reduction occurs at the cathode

• oxidation occurs at the anode

• e- flow anode to cathode

• the sign of the cathode is negative

• the sign of the anode is positive

Nernst equation theory

• Q < 1 means more reactants (E>E knot)

• Q = 1 means equal ratio of products to reactants (E=E knot)

• Q >1 means more products (E<E knot)

• Q = K means the system is at equilibrium (E=0)

What is the value of a Faraday?

9.65 × 10^4 C

aluminum

• lightest metal commonly used in commercial applications

• obtained from the energy intensive Bayer Process (bauxite rocks —> aluminum oxide) and the Hall Process (aluminum oxide —> aluminum)

• the oxite forms ruby, sapphire, and topaz gemstones

alkali metals

• have large radii, low ionzation energy, low electronegativity, and form +1 cations

• oxides and hydrides are basic

• metal displacement reaction with water: M + H2O —> M^+n + OH- + H2

• react vigorously in water (coinage metals [Cu, Ag, Au, Pt] do not)

beryllium

• forms covalent bonds because of its small size and ability to attract electrons

calcium

• in building materials from concrete to teeth

Mg2+

• in chlorophyll

  • makes the molecule more rigid to permit electron transport for photosynthesis instead of energy loss through vibrations

Group 1 Metals

• react in cold water (explode)

Group 2 metals:

• React in hot water

Transition metals

• react in acid

Coinage metals

• do not react

displacement reactions of metals

• most reactive metals are in the lower right corner (Li is the strongest reducing agent)

• least reactive metals are in the top right corner (Au is the weakest reducing agent)

• General displacement reaction: M1 + M2X —> M2 + M1X — metal 1 is more active and replaces metal 2

What are the demands of a modern battery?

• small

• cheap

• high power

• long life

• reversible

• environmentally safe

how are secondary batteries built with consideration?

• minimize liquid or gas production, so contents of the reaction are contained in the battery casing for recharging

What is wrong with lithium-ion batteries?

• they catch on fire — ex) they’re not allowed as commercial cargo on places

Li-ion batter parts

From left to right

• Cathode (+)

• Electrolyte (contains everything)

• Lithium-metal oxide

• porus seperator

• lithium ion + lithium-carbon (graphite)

• anode (-)

battery design

• modern batteries are made with solids and pastes rather than liquids and gases to avoid losses of material

• primary batteries are single use. Rechargeable = secondary batteries are environmentally superior and convenient

• inefficient batteries produce heat, not work. Controlling heat dissipation is important practically and for safety

• Lightweight batteries use less dense, higher charge density materials (like lithium)

Primary Batteries

• disposed of after one cycle

• famous batteries include:

  • common alkaline battery (ex: Duracell) — used in household appliances

  • Zn-C battery — used in hearing aids

Secondary barreries

• reversible (reusable/rechargeable)

• built with consideration

• famous batteries include:

  • Lithium-ion batteries — used in electronics and electric cars

  • lead-acid batteries — used in gas-powered vehicles, recharged by an alternator

  • NIMH (replacing NiCd [know both]) — used in household appliances

rust in the real world

• Rust is made from the oxidation of iron in the presence of water and air for a long period of time

• Fe + H2O + O2 —> Fe(OH)2 + Fe(OH)3

• Rusting can be prevented by adding metals that are easier to oxidize through specific processes:

  • Galvanization with Zn

  • Sacrificial electrodes with Mg, Al

  • Stainless steel with Cr and V added through Fe

  • Waxes and coating