Unit B:

Chapter 1: 1.1 Products of Combustion Reactions


combustion reactions:

  • occur in the presence of oxygen

  • produce an oxide and water

  • emit energy


ex. Hydrocarbon Combustion

  • cellular respiration, burning of fuel, etc.

  • CH4 (g) + 2 O2 (g) > CO2 (g) + 2 H2O (g)


practice balancing reactions*


oxides of carbon:

  • burning carbon compounds or anything with biomass or hydrocarbons result in carbon dioxide

  • some natural forms of CO2 production are forest Fires, weathering of rocks, volcanic eruptions, cellular respiration, etc

  • CO2 is important in the carbon cycle and as a greenhouse gas

    • contributes to climate change


carbon monoxide:

  • common product of combustion

  • produced when O2 is limited

  • very dangerous since it is colourless and odourless


oxides of sulfur:

  • found when coal, crude oil, or tar are burned

  • found in natural gas as sour gas (hydrogen sulfide)

  • sour gas needs to be “sweetened“ meaning the hydrogen sulfide needs to be removed otherwise it is toxic


oxides of nitrogen:

  • nitrogen occupies 78% of the gases in our atmosphere

  • always present whenever any fuel is combusted

  • if the combustion temp reaches 650 degree celsius, nitrogen activates and forms Nitric oxide and nitrogen dioxide

  • common sources are combustion of fuels in cars/furnaces and fossil fuel power plants


natural sources of SO2 (sulfur dioxide):

  • hot springs

  • volcanic outgassing


vs human-made:

  • emissions from:

    • coal-fired power plants

    • refining crude oil/oil sands

    • automobiles


natural sources of NO2 (nitrogen dioxide):

  • forest fires


vs human-made:

  • fossil fuel power plants

  • industrial/domestic furnaces

  • burning of crops

  • automobiles


metals and metal oxides

  • some metals, like mercury and lead, may combine with oxygen to produce metal oxides (through combustion)


1.2

empirical definitions:

  • the description of a substances response to tests performed during an experiment


acid:

  • pH lower than 7

  • sour taste

  • turns blue litmus to red

  • reacts with metals and forms H2 (g) - bubbles

  • electrolytes


base:

  • pH higher than 7

  • bitter taste

  • turns red litmus to blue

  • electrolytes


neutral:

  • pH of 7

  • no taste

  • no effect on litmus

  • both electrolytic and non-electrolytic


arrhenius’ theory

  • acids form aqueous solutions that contain H+ (aq) and an anion

  • bases for aqueous solutions that contains a cation and OH- (aq)

  • neutral electrolytes are those that conduct electricity but do not produce H+ (aq) or OH- (aq) ions


MODIFIED arrhenius theory

  • includes the existence of the H3O+ (aq) hydronium ion in an acid

  • research done by Bronsted and Lowry


acid-base reactions

  • hydrogen is reffered to as a proton

  • a proton is transferred from an acid to a base, during an acid-base reaction

  • the products formed are called a conjugate acid and conjugate base


proton hopping:

  • in an acid-base rxn:

    • a collision between a water molecule and the acid resulted in a transfer of a H= ion to the water molecule to produce the hydronium ion, H3O+

    • followed by a collision of the hydronium ion with the base, resulting in the transfer of the H+ to the base

    • this is described as proton hopping from an acid to the base


acid deposition:

  • emissions that are from human sources are anthropogenic

    • from combustion of energy sources

  • there emission combine with water to form acid rain = acidic deposition

  • rain is acidic due to natural and human sources

    • the degree of acidity can be measure using pH


pH and the pH scale

  • concentration of acids can be represented using a pH scale

  • a pH of 7 is considered neutral

  • pH less than 7 is acidic

  • pH greater than 7 is basic


1.3

what is acid deposition?

  • the process by which acids are chemically formed in the atmosphere and then deposited to the Earth

  • wet deposition:

    • acid precipitation (rain, snow, hail)

    • condensation from acid fog

  • dry deposition:

    • acid dust from dry air


what causes acid deposition?

  • acids in the atmosphere are formed primarily from the production and emission of gases into the atmosphere

  • these gases are oxides of carbon, sulfur, and nitrogen and if released into the atmosphere, these emissions are called anthropogenic emissions


note:

  • the higher levels of oxides of carbon, sulfur, and nitrogen released in the atmosphere, the higher the concentration of hydronium ions in the moisture of the atmosphere

    • DIRECT relationship

  • as the levels of oxides increase, the concentration of hydronium increases, so the pH of moisture decreases (becomes more acidic)

    • INVERSE relationship


effects of acidic deposition:

  1. acid deposition may react chemically with other substances in water

    • pH of most bodies of water in Alberta is above 7.0 and as high as 8.3

    • slightly basic and contains carbonate ions

    • when acid deposition occurs into the waters, the carbonate ions will chemically react with the hydronium ions (from acid deposition) and form a neutralization reation

  2. pH due to the basic waters of Alberta

    • soils have high potential for neutralizing acidic deposition

    • buffering: the neutralization of acids by bases that prevents any change in the pH of a soil or lake

    • effects of acid deposition on metals and other structures:

      • corrosion, rust

      • dissolving of marble and limestone

    • effects o plant life:

      • can convert nutrients that plants need into an insoluble form

  3. leaching

    • releasing of harmful metal ions into the soil

    • destructive to plant growth and toxic to animals through biomagnification

      • when an organism cannot remove a harmful substance such as mercury from its body, its concentration is higher than the environment

      • when that organism is consumed by another organism, the larger organism eats multiples and ends up with a high concentration of mercury


1.4

qualitative data:

  • data concerning the properties, characteristics, or attributes of a substance


quantitative data:

  • data involving a measurement and a numerical magnitude of a substance


titration:

  • a technique for determining the concentration of a substance by adding a measure quantity that it is known to react with until an endpoint is reached

  • equipment used:

    • burette, erlenmeyer flask, pipette, stand

  • goal is to determine the volume of the standard solution required to reach endpoint


standard solution:

  • known concentration solution (in burette) titrated with unknown solution (in flask)


indicator:

  • helps determine when pH change has occurred


endpoint:

  • when the colour change occurs


buffering:

  • net effect of a buffer is to maintain the pH at a relatively constant level


1.5

electrostatic precipitator:

  • uses electric fields to collect fly ash (small particles of sand and other unburned material that remains after coal is combusted)


scrubber:

  • used to remove a gas from a mixture


catalytic converter:

  • used to remove NO gas and CO gas and hydrocarbons from vehicle exhaust


liming:

  • neutralize acid in soil or water by adding base


what happens if we don’t remove NO2?

  • it collects in the troposphere and makes photochemical smog

  • VOCS (volatile organic compounds) can react with this to make PAN (peroxyacetyl nitrate) a respiratory irritant


Chapter 2: 2.1

single bonds: saturated

  • end with ane

double bonds & triple bonds: unsaturated

  • end with ene (double) and yne (triple)


benzene:

  • component to gasoline and restricted in age because it is

    • carcinogenic

    • concerns with leaching if split in water or soil

    • cleaned up with remediation

  • ring structure making it stable


PAHs - polycyclic aromatic hydrocarbons

  • produced by incomplete combustion of oils from foods and from diesel emissions

  • can interact with DNA and potentially cause mutations


synthetic organic molecules:

  • human-made organic compound


functional group:

  • an arrangement of single atoms or groups of atoms, other than carbon or hydrogen, attached to an organic molecule


halogenated hydrocarbons:

  • group 17 in the periodic table

  • a hydrocarbon that has one or more hydrogen atoms replaced by atoms of chlorine, fluorine, bromine, or iodine


CFC’s and ozone:

  • non-flammable and non-toxic

  • used in air-conditioners and refrigerators

  • destroy the ozone later


free radicals:

  • can have damaging effects on our bodies

  • chemicals have an unpaired electron in the valence shell

  • react easily with other substances to fill this shell

  • exposure to radiation may result in the production of oxygen-containing free radicals and DNA affecting the function of body cells


2.2

alcohols:

  • organic molecule that contain a hydroxyl functional group

  • soluble in water

  • polar molecules

  • ex. methanol: found in solvents and fuels, will cause blindness or be fatal

  • ex. glycol found in solvents

  • ex. isopropanol found in disinfectants

  • ex. ethanol found in solvents, fuels, alcoholic beverages


carboxylic acids:

  • a carbonyl functional group is formed by the joining of an oxygen atom to a hydrocarbon by a double bond

  • a carboxylic acid is a functional group formed by the joining of a single C atom to a single O atom with a double bond and a hydroxyl group OH (or alcohol) with a single bond

  • carboxyl groups have the carbonyl group and the hydroxyl group

  • ex. vinegar, citrus fruits, vitamic C


esters:

  • alcohols and carboxylic acids react to form esters

  • esterification is the process of creating an ester by removing the H from the alcohol and the OH from the hydroxyl group in the carboxylic acid


polyesters:

  • a polymer of many ester functional groups

  • created from the reaction of many alcohols and carboxylic acids forming long chains or filaments


2.3

VOCs

  • off gassing

    • an important environmental concern

    • the release of volatile organic compounds from building materials such as paints, lumber, flooring, etc

  • to reduce exposure:

    • use materials that do not contain it

    • avoid direct contact

    • work in ventilated areas


pesticides:

  • a substance that is used to kill fungi, insects, animals or plants considered pests

  • considerations when using pesticides:

    • specificity:

      • like a target: the range of organisms affected by the pesticide

      • broad spectrum pesticide: a chemical substance that can control the population of a large variety of organisms

      • toxicity: the ability to cause damage to living tissue

        • LD50 is the dosage of a chemical substance that kills 50% of the population tested within a specified time

        • LC50 is the concentration of a chemical substance in air or water that kills 50% the population tested within a specified time


drift: the transfer of the pesticide by wind or air currents from the location where it was sprayed


grasshopper effect: the transport of pesticides that result from the evaporation in warmer climates and condensation in colder climates


persistence: the resistance of a chemical substance being broken don by biological or chemical means


water quality:

  • can be affected by acid deposition, persistent organic compounds, and the leaching of metal ions, fertilizers or organic matter

  • can result in algal blooms

    • leaching of fertilizers and organic matter, rich in nitrogen and phosphorus

    • BOD is a measure of amount of oxygen required for the decomposition of organic matter

    • high levels of organic matter (high BOD) demostarte a large reduction in dissolved oxygen concentration