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Gas laws and global warming

Gas laws

General gas laws: There are 3 main gas laws that describe the chemical and physical properties of gases. In order to understand the gas law equations, one must have an elementary understanding of the following relationships: quantity of gas in numbers of moles (n), volume (V), temperature (T), and pressure (P). The three main gas laws have been derived from observations of the effects on gas volume of changing temperature, pressure, and quantity of gas. Boyle’s law, Charles’ law, and Avogadro’s law are the names of the three main gas laws. Boyle’s law states that at a constant temperature, the volume of a fixed quantity of gas is inversely proportional to the pressure of the gas. This can be mathematically illustrated by the equation; V= (a constant) x 1/P. Charles’ law states that the volume of a fixed quantity of gas is directly proportional to the absolute temperature (in Kelvin) at a constant pressure. The mathematical equation of Charles’ law is V= (a constant) x T. According to this statement, doubling the absolute temperature of a fixed quantity of gas at a constant pressure will result in doubling the volume. Finally, the Avogadro’s law states that at constant temperature and pressure, the volume of a gas is directly proportional to the number of molecules of gas, commonly expressed as moles. Mathematically, this equation looks like, V= (a constant) x n. these three gas laws may be combined to one general gas law, which states that the volume of a quantity of ideal gas is proportional to the number of moles of gas and its absolute temperature and inversely proportional to its pressure. Mathematically, this law is V= (a constant) x nT/P. Because we are using ideal gases, we can designate the proportional constant with an ideal gas constant, R, which gives the ideal gas equation: V= RnT/P. Whereas R= 0.0821. In conclusion, these formulas are the main gas laws for which we compute the relationships between volume, pressure, temperature, and quantity of gas in moles.

The Ozone in the stratosphere

The ozone layer is a layer of gas molecules that reside in the stratosphere and protects living organisms from the damaging ultraviolet (UV) radiation. It is mostly made up of an inorganic molecule with the chemical formula O3. This ozone molecule is created by UV light striking oxygen molecules containing two oxygen atoms (O2); the single oxygen atom (atomic oxygen) then combines with an O2 molecule to create an ozone (O3) molecule. When UV light strikes an ozone molecule, it splits it back into an O2 molecule and an atomic oxygen molecule. The continuing process is called the ozone-oxygen cycle. Chemically, this can be described as, O2 + hv(uv)→ 2O. Whereas hv is the photon (light particle) and uv is ultraviolet radiation. Additionally, the second part of the chemical reaction formula is, O + O2←→ O3 (where as the double sided arrow is representing the reversibility of this process). This can be depicted as in Fig. 1.0.

Fig. 1.0

It is currently understood that the ozone layer in the stratosphere does not cause global warming. The ozone absorbs ultraviolet light from the sun and heats the lower stratosphere. However, this accounts for less than one percent of the total solar energy reaching our atmosphere. Due to humans introducing (i.e. refrigerant, aerosol) chlorofluorocarbons (CFCs) and other emissions into the atmosphere, the ozone layer is depleting, which is resulting in a cooling down of the stratosphere. Therefore, the ozone layer is not responsible for global warming; however, global warming does affect the ozone layer. Furthermore, when CFCs reacts with UV radiation, it produces a Cl-ion (CFC→ Cl), which then reacts with the ozone layer multiple times (first time) (Cl+O3→ClO+O2+e-) (second)(ClO+O3→Cl +2O2). Thus the process continues and may allow one molecule of CFC to destroy 10^5 molecules of O3.

Green house gasses in troposphere

The primary greenhouse gasses (GHG) in the atmosphere are water vapor, carbon dioxide (CO2), methane (CH4), and ozone (O3). GHG are defined as gases that can absorb infrared (IR) radiation, but not radiation in or near the visible spectrum. Since the industrial revolution (1750), the burning of fossil fuels and extensive clearing of native forests has contributed to a 40% increase in the atmospheric concentration of CO2, ranging from 280 ppm (parts per million) to ~400ppm. Ranking the four main GHG by their direct contribution to the greenhouse effect, we have the following: water vapor and clouds (H2O) (36-72% contribution); carbon dioxide (CO2) (9-26%); methane (CH4) (4-9%); and ozone (O3) (3-7%). There are additional GHG that play roles in the greenhouse effect, however, they are found in very small quantities and have short “life spans” (how long it takes for a GHG to leave the atmosphere). Additionally, the Earth naturally gains heat from the solar radiation and loses heat by allowing it to escape back into space. Earth’s surface temperature depends on this balance, and if this balance were to be tipped to one side or the other (blanket effect caused by global warming), then there would be noticeable changes in the global climate. Furthermore, a unit of measurement used to describe the ability of molecules to retain or release energy is referred to as radiative forcing (usually measured in watts/meters squared). If the radiative force is positive, then this tells you that there is a gain of heat, correspondingly, if the number were to be negative, then this would demonstrate a loss in heat. The following chart (Fig 0.1) will compare pre tropospheric CO2 concentrations with current tropospheric CO2 concentrations. Additionally, Fig 0.2 will demonstrate the seven main fossil fuel combustion sources and their contribution percentage, which are the primary sources of rising levels of CO2 in the troposphere.

Fig. 0.1

Gas Pre-1750 tropospheric concentration Recent tropospheric concentration Absolute increase since 1750 Percentage increase since 1750 Increased radiative forcing (W/m2) Carbon dioxide (CO2) 280 ppm 395.4 ppm 115.4 ppm 41.2% 1.88 Methane (CH4) 700 ppb 1893 ppb / 1762 ppb 1193 ppb / 1062 ppb 170.4% / 151.7% 0.49 Nitrous oxide (N2O) 270 ppb 326 ppb / 324 ppb 56 ppb / 54 ppb 20.7% / 20.0% 0.17 Tropospheric ozone (O3) 237 ppb 337 ppb 100 ppb 42% 0.4[51]

Fig. 0.2

Seven main fossil fuel combustion sources Contribution (%) Liquid fuels (e.g., gasoline, fuel oil) 36% Solid fuels (e.g., coal) 35% Gaseous fuels (e.g., natural gas) 20% Cement production 3 % Flaring gas industrially and at wells < 1% Non-fuel hydrocarbons < 1% "International bunker fuels" of transport not included in national inventories 4 %

Conclusion

In conclusion, with this information as well as in the following chart (Fig 0.3), there is a definite correlation between the warming of the climate and the rise in CO2 levels (recently caused by humans). In other words, the greenhouse gasses in the troposphere is the definite cause of global warming, not the ozone in the stratosphere.

Fig. 0.3