Global Warming & Climate Change

Global Warming and Climate Change

• Greenhouse gases trap heat in Earth's atmosphere, leading to a warmer temperature than without them. This is known as the greenhouse effect
• Carbon dioxide and methane are examples of common greenhouse gases that maintain a steady temperature on Earth

The Natural Greenhouse Effect

• Solar radiation includes infrared, visible light, and ultraviolet (UV) radiation
• Roughly 30% of solar radiation reaching Earth gets reflected back into space because of the Earth's surface and atmosphere's albedo
• About 22% of incoming solar radiation is absorbed by the atmosphere directly
• The Earth's surface absorbs about 48% of the sun's radiation, resulting in its warming
• Roughly 17% of the absorbed solar radiation is emitted back as thermal infrared radiation
• Solar radiation is emitted back at lower energies, resulting in longer wavelengths within the thermal infrared region of the electromagnetic spectrum
• Only about 12% of thermal radiation passes through the atmosphere into space
• Around 5% of thermal radiation gets absorbed by greenhouse gases in the atmosphere
• Greenhouse gases absorb specific wavelengths of infrared radiation emitted by Earth
• Molecules of greenhouse gases then reradiate thermal radiation to other molecules in the atmosphere, into space, and towards the Earth's surface
• This natural process warms Earth's surface and the troposphere.
• The natural greenhouse effect sustains life on Earth by maintaining a relatively stable average temperature of 15°C

Greenhouse Gases

• Greenhouse gases absorb thermal radiation in the infrared region of the electromagnetic spectrum and come from natural and synthetic sources
• Carbon dioxide (CO2) and methane (CH4) are strong absorbers of infrared radiation

Other Greenhouse Gases and Human Impact

• Other naturally occurring greenhouse gases include water vapor (H2O), nitrous oxide (N2O), and ozone (O3)
• Human activities increase the concentration of naturally occurring greenhouse gases and also introduce synthetic greenhouse gases

Earth's Thermal Balance and Global Warming

• Earth's surface is approximately 32°C warmer with greenhouse gases present
• Carbon dioxide and water vapor most strongly influence the greenhouse effect
• Thermal balance is achieved when the amount of thermal radiation entering the atmosphere equals the amount emitted back into space
• Rising concentrations of greenhouse gases from human activities trap more thermal radiation, creating a thermal imbalance and global warming, known as the enhanced greenhouse effect

Anthropogenic Sources and Atmospheric Residence of Greenhouse Gases

• Carbon dioxide (CO2) sources

  • Combustion in internal combustion engines (5-200 years in atmosphere)
  • Electricity generation in power stations and industries (5-200 years in atmosphere)
  • Deforestation reducing CO2 removal via photosynthesis(5-200 years in atmosphere)

• Methane (CH4) sources

  • Mining, fuel production and usage (12.4 years in atmosphere)
  • Digestion of ruminant animals in intensive livestock farming (12.4 years in atmosphere)

• Nitrous oxide (N2O) sources

  • Natural and synthetic fertilizers, and soil cultivation (120 years in atmosphere)
  • Catalytic converters in vehicles (120 years in atmosphere)

Ocean Acidification

• Ocean acidification results from the absorption of higher levels of atmospheric carbon dioxide by the ocean
• Water exposed to air slowly becomes mildly acidic as atmospheric carbon dioxide dissolves, reacting with water to form carbonic acid (H2CO3): H2O(l) + CO2(g) ⇌ H2CO3(aq)
• Carbonic acid, a weak acid, partially ionizes in water: H2CO3 + H2O ⇌ HCO3- + H3O+
• The hydrogen carbonate ion (HCO3-) can further ionize to form carbonate ions (CO32-): HCO3- + H2O ⇌ CO32- + H3O+
• The pH scale measures acidity based on hydronium ion concentration: pH = -log[H3O+]

pH Calculations

• Hydronium ion concentration: [H3O+] = 10-pH
• pOH calculation: pOH = -log[OH-]
• Relationship between pH and pOH: pH + pOH = 14

pH Impact on Marine Life

• Marine organisms with calcium carbonate exoskeletons and shells are vulnerable to dissolution at low pH
• Decreasing pH reduces available carbonate ions, limiting shell and skeleton formation in marine calcifying organisms

Chemical Equation of Sulfuric Acid and Calcium Carbonate

• Balanced Chemical Equation: CaCO3 + H2SO4 → CaSO4 + H2O + CO2
• Ionic Equation: CaCO3(s) + 2H+ → Ca2+ + H2O + CO2

Photochemical Smog

• Nitrogen oxides form in high-temperature engines and furnaces

Formation of Nitrogen Oxides

• Nitrogen's triple bond makes it stable, requiring energy to form new compounds
• Energy for nitrogen conversion comes from both natural phenomena and human activities

Natural Sources of Nitrogen Oxide

• Lightning
• Volcanic activity
• Bushfires

Anthropogenic Sources of Nitrogen Oxide

• Internal combustion engines
• Jet engines
• Industrial kilns and furnaces

Reaction for Nitric Oxide (NO) formation

• N2(g) + O2(g) → 2NO(g)

Reaction for Nitrogen Dioxide (NO2) formation

• 2NO(g) + O2(g) → 2NO2(g)

Definition of Photochemical Smog

• It is a combination of primary pollutants released by human activities or formed through reactions between primary pollutants and atmospheric molecules

Primary Pollutants

• Substances released directly into the atmosphere from human activities like combustion
  • Eg - NO (nitric oxide)
  • CO (carbon monoxide)
  • CO2 (carbon dioxide)
  • SO2 (sulphur dioxide)
  • unburnt hydrocarbons.

Secondary Pollutants

• Formed via reactions of primary pollutants with O2 or H2O via sunlight.
  • Eg - NO2 (nitrogen dioxide)
  • O3 (ozone)
  • SO3 (sulphur trioxide)
  • peroxyacetyl nitrates (PANs)
• Ozone is desirable in the stratosphere, not in the troposphere

Conditions Necessary for Photochemical Smog Formation

• High concentration of pollutants (densely populated, industrialised cities, with pollutant concentrations periodically changing throughout the day)
• Sunlight (reactions are initiated by UV radiation and heat)
• Still air mass (pollution can be dispersed by weather patterns)
• Temperature inversion (warmer air with pollutants gets trapped between cooler, denser air)
• Valley topography (valleys trap air pollutants)

Composition of Smog

• Ozone (O3)
• Nitrogen dioxide (NO2) is responsible for the brown haze

Formation of Secondary Pollutants

• The level of ozone in large cities is an indicator of photochemical smog

Formation of Nitric Oxide

• N2(g) + 02(g) → 2NO(g)

Impact on the Environment

• Increased concentrations of ozone and nitrogen oxides greatly affect the natural and built environments

Negative Effects of Smog

• Humans- Causes irritation in eyes. Oxides of Nitrogen can react with the fluid in the eyes, making them more acidic (nitric acid). Ozone in smog irritates the respiratory system and reduces oxygen diffusion affecting the elderly.
• Enviromental- causes ozone/greenhouse global warming
• Materials- ozone deteriorates rubber by attacking the double bonds in long chain molecules of rubber and other polymers, breaking the chains and forming cross-links between chains

Reaction of Nitrogen Dioxide

• 2NO2 + H2O → HNO3 + HNO2: acid rain which Damages buildings and increases acidity of waterways

Catalytic Converters

• Required by law
• Reduces carbon monoxide and oxides of nitrogen
• Catalytic converters consist of a honeycomb structure that has group metals coated on the surface.
• When in contact, exhaust gases react with the catalyst.

Reaction 1

• CO is oxidised to CO2
• Equation: 2CO + O2 → 2CO2

Reaction 2

• Unburnt hydrocarbons combust to CO2 and water
• Equation: C8H18 + 25/2 O2 →8CO2 + 9H2O

Reaction 3

• NO is reduced to N2.
• Equation: 2NO + 2CO → N2 + 2CO2

Volumetric Analysis and Essential quantities, formulas, and Conversions

• A measure of the amount of the matter is mass (Grams)

• the space a substance occupies is volume (L)

• Density is a mass per unit volume measured in kg per L

• Avogadro's Constant, NA

  • The number of fundamental particles contained in exactly 12 g of carbon 12 is 6.022 × 1023, this number represents Avogadro's constant., Mol-1

• Mole is measuring measurement of the fundamental particles (atoms, ions, molecules, formula unit) in a given mass of material, measured in mol

• Molar Mass is the mass of one mole of a substance, g.mol-1

• M = n×M

• Various conversions between, between units using M

Molar Concentration or molarity

• amount of solute, in mol, present in 1.00 L of solution.

  • Concentration (mol/L)

Mass Concentration

• gram (g)present in 1/L solution

Conversions

• Parts Per Million mg present in 1 kg of solution
• Parts per Billion g micrograms(µg) present in 1 kg of solution.
• M -> g/L -> ppm-> ppb

Chromatography Principles

• Separation, identification, and quantification of components within mixtures based on differential adsorption and solubility
• Techniques are used in analysis, science, pharmaceutical testing, etc.

The Strength of Interactions Between Phases

• Separations happen because of the extent of the interactions between phases
• More strong interactions causes a slower rate
• The polarity, size, and charge of the mixture is important for the interactions
• The attachment of particles onto the surface of the material causes Adsorption.
• The Adsorption chromatography is where the mobile phase move
• Rate depends on strength of the secondary interactions

Normal vs Reverse Phase Chromatography

• Normal Phase chromatography is where the polarity of the stationary phase is greater than that of the mobile phase, meaning more polar components= more bonding= slower rate
• Reverse Phase chromatography is that the polar components bond weakly with the nonpolar phase
• TLC uses either of the above phases and thin layer of absorbent material which separates the components of a mixture

Thin Layer Chromatography

• Solvent moves up the plate, and different rates of movement cause separation
• In normal phase chromatography, more polar components bond more strongly and move more slowly
• In reverse phase chromatography, more polar components bond weakly and move more freely

Rf Retardation Factor

• Rate is measured by a ratio referred to Retardation Factor(RF)
• An Revalue closer to one indicates that the component has travelled to a position close to the
• Used to identify what components are present in the mixture
• Column chromatography uses the same principals to find unknown compounds

Column Chromatography

• Not unlike a burette.
• Contains a absorbent which separates the components elutes, or leaves, the mixtures.
• Not like thin layer chromatography, no RF is generated
• Retention time is the time taken for substance to pass through the column.
• Gas chromatography (GC) works for gas. Has detectors which measure the output, creates peaks.
• Retention time shows qualities of the chemicals in the compounds.

Qualitative And Quantitive Analysis

• -By comparing retntion to known compounds, and peaking, can tell which/what ones are there.

High Pressure Liquid Chromatography

• -for components of high points. High temp gas isn’ to applicable. Components travel and measure to find.

Rate Of Adosportion

• -in chromatography, phase opposite to moblie phase. Polar attracted with a nonpolar will use Polar moblie

Atomic Spectroscopy

• Flame tests and AAS is needed to find elements

Principles of Spectroscopy

• Used for Elements because its unique to each atom. Metals produces different flame colors

Limitations of Flame Tests

• Includes low sensitivity, subjectivity,interference and lack of quantifications

Using Subshell Notation for Electronic Configurations

Electron has 2 in K, 8 on shell

• To right notation for configuration uses shell notations
• The closer to being filled the subshells orbitals are more stable
• Elements in the same group have similar chemical properties
• All radiation elements have wavelengths which determines unique structure

Atomic Spectroscopy and Electromagnetic Radiation

• Uses atomic electromagnetic radiation to deduce
• Energy comes in quantized form
• Spectrum has 3 phases: emission, aborption and lumoniscence.