Exam Review Ch 4 Energy from Combustion Ch 6 Neutralizing the Threat of Acid Rain Chapter 6 Acids Bases and Ocean Acidification 1 Arrhenius Definition of Acids Bases Acids and Bases in Water 1 Acid Anything that reacts with water to form H3O Hydronium ion 1 The hydronium ions are the actual acid molecules 2 Base Anything that reacts with water to form OH Hydroxide ion 1 The hydroxide ions are the actual base molecules 2 Ions 1 Cations Anions 1 Cations positively charged ions ie H3O 1 Groups 1 and 2 2 Anions negatively charged ions ie OH 1 Groups 5 6 and 7 2 Ionization energy and Electron affinity 1 Ionization energy How easily an ion loses an electron 1 Lower IE cation Higher IE anion 2 Electron affinity How easily an ion gains an electron 1 Lower EA cation Higher EA anion 3 Periodic properties and Ion formation 1 Both Ionization energy and Electron affinity increase across a row 2 Acids Ion formation 1 H can t exist alone because it is too reactive so it forms H3O in water 3 Bases Ion formation 1 There is an indirect formation of OH 1 NH4 H2O NH4 OH ie Ammonia takes a proton from water making NH4 as an acid and OH In this case water acts 4 Conjugate Acids Bases 1 Conjugate acid base pair 2 substances whose formulas only differ by an H ion Exam Review Ch 4 Energy from Combustion Ch 6 Neutralizing the Threat of Acid Rain 1 Conjugate acid Formed by a gain of H to base 2 Conjugate base Formed by loss of H from acid 4 Polyatomic Ions Ions with more than one atom 1 Most are Oxygen another element ie SO4 2 which has 48 protons but 50 electrons 1 Found in Water H3O OH HCO3 2 Other important Polyatomic ions Ammonium NH4 Carbonate CO3 2 Bicarbonate 3 Self Dissociation of Water 1 H2O H2O H3O OH 2 For this to happen 1 Temperature must be at 25oC 1 This reaction is constantly happening autohydrolysis in any water ie Water in a water bottle 2 Concentrations of both H3O and OH must be 1 x 10 7 making the total concentration of ions 1 x 10 14 1 This is called the autohydrolysis constant of water also known as Kw 1 x 10 14 1 Kw can be used to find ion concentration or pH 1 See Sample Calculations Exam 2 1 on Blackboard to see how this is done 4 The pH scale 1 Ranges from 1 14 with 1 being most acidic 7 being neutral and 14 being most basic 2 To find pH the product of concentrations of both H3O and OH must be 1 x 10 14 1 Neutral solutions will have concentrations of both H3O and OH at 1 x 10 7 2 Acidic solutions H3O 1 x 10 7 OH 1 x 10 7 3 Basic solutions H3O 1 x 10 7 OH 1 x 10 7 3 pH H3O ie If the concentration of H3O is 1 x 10 5 then pH 1x10 5 so pH 5 5 Acid and Base Strength 1 Strong Acids give up H easily and have 100 dissociation in water 2 Weak Acids don t give up H as easily and have less than 100 dissociation in water 1 The same goes with Strong Weak bases but rather than H the ion being given up is OH Exam Review Ch 4 Energy from Combustion Ch 6 Neutralizing the Threat of Acid Rain 2 Examples 1 Strong Acids HCl HF HBr HI Hydrogen other group 7 elements 2 Weak Acids Formic acid acetic acid and most other organic acids 3 Strong Bases NaOH LiOH KOH RbOH Hydroxide other group 1 elements 4 Weak Bases NH3 and other combinations of ammonia 2 Acid Dissociation Constants 1 Measure of acid strength Ka The bigger the Ka the more hydronium in the acid 1 Strong acids have Ka 1 Weak acids have Ka 1 1 Most organic acids have Ka near 10 5 proving them weak 6 The Acidity of Rain Acid Rain 1 Normal rain is acidic H2CO3 1 CO2 in atmosphere slightly dissolves in water and reacts to produce slightly carbonic acid 1 Acid Rain comes from oxides of sulfur and nitrogen aka SOx and NOx 1 Most found in eastern third of US due to industrialization 2 Normal ocean water is basic 1 This is due to CaCO3 Calcium carbonate 7 Ocean Acidification 1 Lowering of ocean pH from increased atmospheric CO2 2 Carbonate System in the Ocean 1 CO2 dissolves in the ocean and forms carbonic acid bicarbonate 2 H3O from carbonic acid reacts with carbonate already in ocean causing it to dissolve 3 Carbonate is taken from other materials in the ocean dissolved in order to replace the carbonate in step 2 1 This is usually taken from CaCO3 which is what keeps the ocean basic therefore raising acidity 2 See Figure 6 6 on page 251 or lecture notes for diagram 3 Effects of CO2 dissolution in the ocean Exam Review Ch 4 Energy from Combustion Ch 6 Neutralizing the Threat of Acid Rain 1 Eventual dissolving of shells of sea creatures coral and other sea plants dying damage to reefs which will cause the loss of marine life Chapter 4 Energy from Fossil Fuels 1 Electricity Generation 1 Coal powered steam turbine power plant 1 Coal is combusted and boils water in a high pressure system 2 The steam from the water turns the turbine to create electricity 2 Energy Work Heat and Temperature 1 Energy capacity to do work 2 Work movement against a force 3 Heat Energy that flows from a hotter to colder object 4 Temperature Determines direction of heat flow 1 Heat is a consequence of motion Temperature is a measure of heat content 3 1st Law of Thermodynamics Energy conversions 1 Energy cannot be created or destroyed only converted into another type of energy 2 Application of 1st law in Turbines 1 Potential Energy Stored in bonds of fossil fuels 2 Kinetic Energy Motion of steam molecules 3 Mechanical Energy Movement of Turbines 4 Electrical Energy Created by the Turbine 3 Power plants are inefficient 2 Coal 1 Consumption 1 US owns over of the world s coal reserves 1 Coal combustion is more than half all US electricity generation Exam Review Ch 4 Energy from Combustion Ch 6 Neutralizing the Threat of Acid Rain 2 Most coal use is found in Asia 2 Energy content of different types of coal 1 Most energy Anthracite 2 Least energy Wood 3 Oil 1 Distillation and Crude Oil fractions 1 Must be distilled in a distillation tower before use 2 Separated into sections of tower based on amount of carbon atoms in the oil 2 Use 1 1 barrel of oil 42 gallons 1 87 used in transportation and heating 2 Other 13 used in other products ie plastics 3 Peak oil scenarios 4 Energy content 1 peak oil when over half of the crude oil reserves are used up 1 See Sample Calculations Exam 2 3 on Blackboard The Chemistry of …