(unit b) chemistry

• WHMIS Symbols


  • Exploding bomb (for explosion or reactivity hazards)
  • Flame (for fire hazards)
  • Flame over circle (for oxidizing hazards)
  • Gas cylinder (for gases under pressure)
  • Health hazard (may cause or suspected of causing serious health effects)
  • Corrosion (for corrosive damage to metals, as well as skin, eyes)
  • Skull and Crossbones (can cause death or toxicity with short exposure to small amounts)
  • Exclamation mark (may cause less serious health effects or damage the ozone layer)
  • Environment* (may cause damage to the aquatic environment)
  • Biohazardous Infectious Materials (for organisms or toxins that can cause diseases in people or animals)
• The GHS system also defines an Environmental hazards group. This group (and its classes) was not adopted in WHMIS 2015. However, you may see the environmental classes listed on labels and Safety Data Sheets (SDS). Including information about environmental hazards is allowed by WHMIS 2015.
• pH scale


  Allows us to measure degree of acidity
• Ion concentration


  Can be used to approximate pH
• pH scale


  • Acidic
  • Neutral
  • Basic
• Neutral means equal concentrations of hydronium and hydroxide
• For every one number change on the pH scale, there is a 10 fold (10x) difference in the concentration of hydronium ions. This is considered logarithmic.
• Acid-Base Indicators


  Substances that change colour in response to a change in pH
• Acid-Base Indicators at 25°C

  • methyl violet (pH 0.0-1.6, yellow to blue)
  • thymol blue (pH 1.2-2.8, red to yellow)
  • bromyl blue (pH 8.0-9.6, yellow to blue)
  • orange IV (pH 3.1-4.4, red to yellow)
• The more indicators used, the more accurate your estimate of pH will be (a minimum of 3)
• Titrations


  Used to determine the unknown concentration of a solution by adding measured quantities of another solution that is known to react with it until the end point is reached
• Equipment used in titrations

  • Pipette
  • Burette
  • Erlenmeyer flask
  • Indicator
• Steps in a titration

  1. Add the unknown solution and indicator to the Erlenmeyer flask

  2. Record the initial volume of the standardized solution

  3. Slowly titrate the standardized solution into the flask until the endpoint (color change) is reached

  4. Record the final volume of the standardized solution and calculate the volume used
• Buffer


  A substance that resists changes in pH when small amounts of an acid or base are added
• Tums and Rolaids contain carbonate ions which are a great buffer against acids</b>
• Carbonate ion reacts with hydronium ion


  To neutralize the acid and keep the pH the same
• Emissions


  Gaseous pollutants released into the air
• Particulates


  Solid particles released into the air
• Acid deposition


  Includes both wet deposition (acid rain, snow, fog) and dry deposition (gases and particles) with a pH less than 5.6
• Sources of SOx


  • Natural (volcanic eruptions, hot springs)
  • Human-made (burning coal, oil refining)
• Sources of NOx


  • Natural (forest fires)
  • Human-made (burning fossil fuels, high temperature combustion processes)
• In addition to SOx and NOx, other oxides can cause acid deposition, such as CO
• Oil sands


  A naturally occurring mixture of sand, clay or other minerals, water and bitumen, which is a heavy and extremely viscous oil that must be treated before it can be used by refineries
• Sulfur dioxide (SO2) from coal burning and refineries

  Can react with oxygen and water to produce sulfuric acid (H2SO4)
• Nitrogen oxides (NOx) from automobile exhaust

  Can react with water to produce nitric acid (HNO3)
• Effects of acid deposition

  • Changes in soil pH
  • Leaching of nutrients and metal ions into water
  • Death of aquatic populations
  • Defoliation of plants
  • Increased rates of respiratory issues in humans
  • Corrosion of buildings, monuments and statues
• Nutrients available in soil at different pH levels

  • Nitrogen, phosphorus, potassium, sulfur most available in acidic soil
  • Calcium, magnesium, iron, manganese, boron, copper, zinc, molybdenum most available in alkaline soil
• Limestone lake beds have a higher buffering capacity against acid deposition than granite lake beds
• Technologies to reduce emissions

  • Electrostatic precipitators (remove particulates)
  • Scrubbers (remove SOx and NOx)
  • Catalytic converters (reduce NOx, CO, hydrocarbons)
• Liming of lakes with acidic effects can help neutralize the acidity
• Photochemical smog


  A brownish-red haze caused by emissions of NOx and particulates that can cause respiratory issues
• Ozone (O3) formation


  O(g) + O2(g) -> O3(g)
• Tropospheric ozone (ground-level ozone) is bad, while stratospheric ozone (ozone layer) is good
• Organic chemistry


  The study of carbon-containing compounds
• Organic compounds


  Often also contain groups like -OH, -COOH, -NH2, etc.
• Carbon


  • Forms single and double bonds with other elements, such as hydrogen
• Where organic compounds can be found

  • Crude oil
• Things derived from crude oil

  • Gasoline
  • Diesel
  • Lubricating oils
  • Waxes
• Fractional distillation of crude oil

  1. Crude oil is heated

  2. Chemicals in petroleum are separated into different chambers
• The largest molecules are found at the bottom of the fractionating column