Chemistry and the Environment Chapter 1: Acid Deposition Chapter 1: Acid Deposition Chapter 2: The Chemical Legacy of Human Activity Chapter 2: The Chemical Legacy of Human Activity

Acid Deposition 1.1 Products of Combustion Reaction 1.1 Products of Combustion Reaction 1.2 Chemistry of Acids and Bases 1.2 Chemistry of Acids and Bases 1.3 Impact of Acid Deposition on Ecosystems 1.3 Impact of Acid Deposition on Ecosystems 1.4 Quantifying Acid Deposition and Monitoring its Effects 1.4 Quantifying Acid Deposition and Monitoring its Effects 1.5 Learning From Acid Deposition 1.5 Learning From Acid Deposition

1.1 Products of Combustion Reactions A combustion reaction is a chemical reaction that takes place in the presence of oxygen and results in the release of energy A combustion reaction is a chemical reaction that takes place in the presence of oxygen and results in the release of energycombustion reactioncombustion reaction Combustion reactions involve a fuel (often a hydrocarbon) and emissions Combustion reactions involve a fuel (often a hydrocarbon) and emissions hydrocarbon Combustion reactions must be balanced Combustion reactions must be balancedbalanced

1.1 Products of Combustion Reactions Incomplete combustion of hydrocarbons can result in the formation of carbon monoxide Incomplete combustion of hydrocarbons can result in the formation of carbon monoxide Impurities in the fuel can cause the release of Impurities in the fuel can cause the release of 1.Oxides of Sulfur (sour gas) SO x sour gassour gas 2.Oxides of Nitrogen NO x Nitrogen 3.Metals and Metal Oxides 4.Particulate Matter

1.2 Chemistry of Acids and Bases Solutions are homogeneous mixtures with a solute and a solvent Solutions are homogeneous mixtures with a solute and a solvent Aqueous solutions have water as the solvent Aqueous solutions have water as the solvent Solutes can be ionic or molecular Solutes can be ionic or molecular Ionic solutes dissociate in water Ionic solutes dissociate in water Ionic solutes are electrolytic Ionic solutes are electrolyticelectrolytic Molecular solutes dissolve in water if they are polar Molecular solutes dissolve in water if they are polar The concentration of a solution is the amount of solute in a volume of solution (usually expressed in mol/L) The concentration of a solution is the amount of solute in a volume of solution (usually expressed in mol/L)

1.2 Chemistry of Acids and Bases Acids are aqueous solutions that have the following empirical properties Acids are aqueous solutions that have the following empirical properties 1.Electrolytic 2.Corrosive 3.Turns blue litmus red 4.Reacts with active metals to produce hydrogen gas 5.Neutralized by bases 6.Taste sour

1.2 Chemistry of Acids and Bases Bases are aqueous solutions that have the following empirical properties: Bases are aqueous solutions that have the following empirical properties: 1.Electrolytic 2.Corrosive 3.Turns re litmus blue 4.Feels slippery 5.Neutralized by acids 6.Taste bitter

1.2 Chemistry of Acids and Bases Theoretical properties of acids Theoretical properties of acids Arrhenius: acids are molecular solutes that ionize to form H + (aq) Arrhenius: acids are molecular solutes that ionize to form H + (aq) Modified Arrhenius: acids react with water to form hydronium ions H 3 O + (aq) Modified Arrhenius: acids react with water to form hydronium ions H 3 O + (aq) Bronsted-Lowry: acids are molecular solutes that donate protons (H + ) to another substance in a chemical reaction…examples Bronsted-Lowry: acids are molecular solutes that donate protons (H + ) to another substance in a chemical reaction…examplesexamples

1.2 Chemistry of Acids and Bases Theoretical properties of bases Theoretical properties of bases Arrhenius: bases are solutes that ionize to form OH - (aq) Arrhenius: bases are solutes that ionize to form OH - (aq) Modified Arrhenius: bases react with water to form OH - (aq) Modified Arrhenius: bases react with water to form OH - (aq) Bronsted-Lowry: bases are molecular solutes that accept protons (H + ) from another substance in a chemical reaction…examples Bronsted-Lowry: bases are molecular solutes that accept protons (H + ) from another substance in a chemical reaction…examplesexamples

1.2 Chemistry of Acids and Bases Acid deposition is the result of emissions reacting with water to make acidic solutions Acid deposition is the result of emissions reacting with water to make acidic solutionsreacting Anthropogenic emissions are due to human activity Anthropogenic emissions are due to human activityhuman activityhuman activity Acid rain is any form of precipitation containing excess of dissolved acids such that the pH is less than 5.6 Acid rain is any form of precipitation containing excess of dissolved acids such that the pH is less than 5.6pH

1.2 Chemistry of Acids and Bases pH is a common way to represent the concentration of H 3 O + (aq) in a solution pH is a common way to represent the concentration of H 3 O + (aq) in a solution pH pH = -log[H 3 O + ] pH = -log[H 3 O + ] One pH unit is equivalent to a tenfold change in the concentration of H 3 O + (aq) One pH unit is equivalent to a tenfold change in the concentration of H 3 O + (aq) An indicator is a chemical whose colour changes at different pH levels An indicator is a chemical whose colour changes at different pH levels The pH of a solution can be estimated using multiple indicators The pH of a solution can be estimated using multiple indicators

1.3 Impact of Acid Deposition on Ecosystems Acid deposition can affect ecosystems around the globe due to: Acid deposition can affect ecosystems around the globe due to: 1.Wind patterns (jet stream) jet streamjet stream 2.Lake acidification (relatively low buffering capacity) 3.Soil acidification (variable buffering capacity) variable 4.Nutrient and metal leaching (biogeochemical cycles) biogeochemical cyclesbiogeochemical cycles 5.Biomagnification Biomagnification 6.Abiotic effects, biotic effects and declining biodiversity

1.4 Quantifying Acid Deposition Qualitative analysis: recording observable properties of a system Qualitative analysis: recording observable properties of a system Qualitative analysis Qualitative analysis Quantitative analysis: measuring using a numerical value Quantitative analysis: measuring using a numerical value Titration is a method of measuring the concentration of a solution Titration is a method of measuring the concentration of a solution Titration In a titration, the titrant is added to the sample until a chemical reaction is complete In a titration, the titrant is added to the sample until a chemical reaction is complete The volume and concentration of one substance is used to determine the concentration of the other The volume and concentration of one substance is used to determine the concentration of the other

1.4 Quantifying Acid Deposition A titration curve is a graph to represent a titration A titration curve is a graph to represent a titrationtitration curvetitration curve A titration curve can determine the buffering capacity of a solution A titration curve can determine the buffering capacity of a solutionbuffering capacitybuffering capacity A strong acid reacts completely with water to form hydronium ions A strong acid reacts completely with water to form hydronium ions A weak acid reacts incompletely with water to form hydronium ions A weak acid reacts incompletely with water to form hydronium ions Two acids of the same concentration can have different pH levels Two acids of the same concentration can have different pH levels

1.5 Learning From Acid Deposition The effects of acid deposition on ecosystems can be minimized by: The effects of acid deposition on ecosystems can be minimized by: 1.Reducing emissions: cleaner fuels, scrubbing SO X from coal fired plants, catalytic converters removing NO X from vehicle exhaust, and reducing combustion cleanerscrubbingcatalytic convertersreducing combustioncleanerscrubbingcatalytic convertersreducing combustion 2.Recovering from acid deposition: liming acidified lakes and soil liming Reducing NO X can help reduce photochemical smog and the effects of VOC’s Reducing NO X can help reduce photochemical smog and the effects of VOC’sphotochemical smogVOC’sphotochemical smogVOC’s

The Chemical Legacy of Human Activity 2.1 Organic Compounds 2.1 Organic Compounds 2.2 Alcohols, Carboxylic Acids and Esters 2.2 Alcohols, Carboxylic Acids and Esters 2.3 Understanding Exposure 2.3 Understanding Exposure

2.1 Organic Compounds Organic Chemistry: the study of compounds composed of carbon Organic Chemistry: the study of compounds composed of carbon Organic Chemistry Organic Chemistry Hydrocarbons: organic compounds made of only carbon and hydrogen atoms Hydrocarbons: organic compounds made of only carbon and hydrogen atoms Hydrocarbons Saturated Hydrocarbons: hydrocarbons that have single bonds between carbon atoms (alkanes) Saturated Hydrocarbons: hydrocarbons that have single bonds between carbon atoms (alkanes) Unsaturated Hydrocarbons: hydrocarbons that have one or more double bonds between carbon atoms (alkenes) Unsaturated Hydrocarbons: hydrocarbons that have one or more double bonds between carbon atoms (alkenes)

2.1 Organic Compounds Hydrocarbons are named based on the number of carbon atoms they possess and whether the chain saturated or not Hydrocarbons are named based on the number of carbon atoms they possess and whether the chain saturated or not Rules for naming alkanes Rules for naming alkanesalkanes Rules for naming alkenes Rules for naming alkenesalkenes Aromatic hydrocarbons have a benzene ring in the molecular structure Aromatic hydrocarbons have a benzene ring in the molecular structurebenzene Benzene demonstrates a unique chemical bonding arrangement called resonance Benzene demonstrates a unique chemical bonding arrangement called resonance

2.1 Organic Compounds Benzene is very stable and is carcinogenic Benzene is very stable and is carcinogeniccarcinogenic Benzene remediation is necessary to remove benzene contamination from soil Benzene remediation is necessary to remove benzene contamination from soilremediation PAH’s are polycyclic aromatic hydrocarbons and are common carcinogens PAH’s are polycyclic aromatic hydrocarbons and are common carcinogenspolycyclic aromatic hydrocarbonspolycyclic aromatic hydrocarbons Halogenated hydrocarbons have one or more halogen added to an alkane, alkene or aromatic hydrocarbon Halogenated hydrocarbons have one or more halogen added to an alkane, alkene or aromatic hydrocarbon Rules for naming halogenated hydrocarbons (p251) Rules for naming halogenated hydrocarbons (p251)halogenated hydrocarbonshalogenated hydrocarbons

2.1 Organic Compounds Chlorofluorocarbons (CFC’s) are linked to ozone depletion Chlorofluorocarbons (CFC’s) are linked to ozone depletion Chlorofluorocarbonsozone depletion Chlorofluorocarbonsozone depletion Other halogenated hydrocarbons are linked to health and environmental problems Other halogenated hydrocarbons are linked to health and environmental problemshalogenated hydrocarbonshalogenated hydrocarbons

2.2 Alcohols, Carboxylic Acids and Esters Alcohols are hydrocarbons with one or more hydroxyl functional groups Alcohols are hydrocarbons with one or more hydroxyl functional groups functional groups functional groups Alcohols are used for cleaning solvents, disinfectants, fuels, production of pharmaceuticals, dessicants Alcohols are used for cleaning solvents, disinfectants, fuels, production of pharmaceuticals, dessicants Rules for naming alcohols (p264) Rules for naming alcohols (p264)naming alcoholsnaming alcohols Carboxylic acids are hydrocarbons with a carboxyl functional group Carboxylic acids are hydrocarbons with a carboxyl functional group

2.2 Alcohols, Carboxylic Acids and Esters Carboxylic acids are weak acids that include ethanoic acid (vinegar), lactic acid and PABA Carboxylic acids are weak acids that include ethanoic acid (vinegar), lactic acid and PABAlactic acidPABAlactic acidPABA Rules for naming carboxylic acids (same as alcohols but use the suffix “oic acid” Rules for naming carboxylic acids (same as alcohols but use the suffix “oic acid” Esters are formed by reacting a carboxylic acid with an alcohol Esters are formed by reacting a carboxylic acid with an alcohol Esters Esters make up common flavours, odours and fats Esters make up common flavours, odours and fatsfats Rules for naming esters (p272) Rules for naming esters (p272)naming estersnaming esters Many plastics are polymers of esters (polyesters) Many plastics are polymers of esters (polyesters)polyesters

2.3 Understanding Exposure Volatile organic compounds (VOC’s) are chemicals that evaporate or sublimate easily during off-gassing and affect indoor air quality Volatile organic compounds (VOC’s) are chemicals that evaporate or sublimate easily during off-gassing and affect indoor air qualityVOCoff-gassing indoor air qualityVOCoff-gassing indoor air quality Off- gassing affects both human and environmental health Off- gassing affects both human and environmental health Using low VOC products can reduce these problems Using low VOC products can reduce these problemslow VOC productslow VOC products Persistent organic pollutants (POP’s) include pesticides: Persistent organic pollutants (POP’s) include pesticides:POP Broad spectrum: low target specificity and will affect many species Broad spectrum: low target specificity and will affect many species Target Specific: affect one or only a few species Target Specific: affect one or only a few species

2.3 Understanding Exposure Pesticides include Pesticides include Insecticides Insecticides Herbicides Herbicides Fungicides Fungicides Others Others The toxicity of a chemical can be determined by LD 50 or LC 50 testing (Note: low LD 50 means high toxicity) The toxicity of a chemical can be determined by LD 50 or LC 50 testing (Note: low LD 50 means high toxicity)LD 50 or LC 50LD 50 or LC 50 The use of pesticides is subject to drift, the grasshopper effect (p286) and persistence The use of pesticides is subject to drift, the grasshopper effect (p286) and persistencethe grasshopper effectpersistencethe grasshopper effectpersistence

2.3 Understanding Exposure Water quality is affected by fertilizers and organic matter Water quality is affected by fertilizers and organic matter Fertilizers contain nutrients that encourage the growth of algae Fertilizers contain nutrients that encourage the growth of algaenutrients Algal blooms can result in the build up of organic matter and eutrophication of a body of water Algal blooms can result in the build up of organic matter and eutrophication of a body of water eutrophication Low dissolved oxygen concentrations can lead to winterkill of Alberta lakes Low dissolved oxygen concentrations can lead to winterkill of Alberta lakeswinterkill Biochemical oxygen demand is a measure of the rate at which dissolved oxygen becomes depleted in a water sample Biochemical oxygen demand is a measure of the rate at which dissolved oxygen becomes depleted in a water sample

2.3 Understanding Exposure Limiting exposure involves: Limiting exposure involves: 1.Bioremediation Bioremediation 2.Biological controls for pests Biological controlsBiological controls 3.Biodegradeable products 4.Monitoring 5.Education (workforce and the general public)