The Ecological Footprint is defined as the area of productive land and water ecosystems required to produce the resources that the population consumes (food, fiber, timber, energy, and space for infrastructure) and assimilate the wastes that the population produces (CO2 is the only waste product currently included), wherever on Earth the land and water is located. It compares actual throughput of renewable resources relative to what is annually renewed. Non-renewable resources are not assessed, as by definition their use is not sustainable.
Ecological footprints and biocapacity are expressed in global hectares (gha). Each unit corresponds to one hectare of biologically productive space with world average productivity. In U.S. Footprint results are often presented in global acres (ga). One U.S. acre is equal to 0.405 hectares.
Humanity is currently consuming renewable resources at a faster rate than ecosystems can regenerate them and continuing to release more CO2 than ecosystems can absorb. In 2007, humanity's Footprint was 18 billion gha, or 2.7 gha per person. However, the Earth's biocapacity was only 11.9 billion gha, or 1.8 gha per person. This represents an ecological overshoot of 50 per cent. Put another way, people used the equivalent of 1.5 planets to support their activities (more developed countries generally make higher demands on the Earth's ecosystems than poorer, less developed countries).
Gas washing bottle or Drechsel bottle provide an inexpensive but effective method for washing or drying gases. The gas enters the bottle through the top of the central vertical tube, the lower end of which is below the surface of the washing medium. To maximize surface area contact of the gas to the liquid, a gas stream is slowly blown into the vessel through the fritted glass tip so that it breaks up the gas into many tiny bubbles. After bubbling through the medium, the gas rises to the top and exits through the side tube. It is named after the German chemist Edmund Drechsel (1843-1897).
The Living Planet Index (LPI) reflects changes in the health of the planet's ecosystems by tracking trends in nearly 8000 populations of vertebrate species. The LPI first calculates the annual rate of change for each species population in the dataset, then calculates the average change across all populations for each year from 1970, when data collection began, to 2007, the latest date for which data is available.
The Global LPI shows a decline of around 30 % from 1970 to 2007, based on 7953 populations of 2544 species of birds, mammals, amphibians, reptiles and fish.
Oil of vitriol is an obsolete name for sulfuric acid (H2SO4). Very old way of making sulfuric acid is by heating green vitriol (FeSO4*7H2O) to decomposition and collecting the acid vapors evolved.
Practical salinity SP is defined on the Practical Salinity Scale of 1978 (PSS-78) in terms of the conductivity ratio K15 which is the electrical conductivity of the sample at temperature t68 = 15 °C and pressure equal to one standard atmosphere, divided by the conductivity of a standard potassium chloride (KCl) solution at the same temperature and pressure. The mass fraction of KCl in the standard solution is 0.0324356 (32.4356 g of KCl in 1 kg of solution). When K15 = 1, the Practical Salinity P S is by definition 35. The conductivity of that reference solution is C(35,1568,0) = 42.914 mS/cm = 4.2914 S/m (Siemens per meter). Note that Practical Salinity is a unit-less quantity. Though sometimes convenient, it is technically incorrect to quote Practical Salinity in "psu". When K15 is not unity, SP and K15 are related by the PSS-78 equation
At a temperature of t68 = 15 °C, Rt is simply K15 and Practical Salinity SP can be determined from the above equation. For temperatures other than t68 = 15 °C, Practical Salinity SP is given by the following function of Rt (k = 0.0162)
Referent electrode is an electrode whose potential is known and completely independent of analyte concentration. Mostly used referent electrodes are calomel and silver/silver chloride electrode.
Table: Dependence of referent electrodes potentials on KCl concentration
Potential vs. SHE / V | |||||
calomel electrode | Ag/AgCl electrode | ||||
t / °C | 0.1 mol dm-3 | 3.5 mol dm-3 | sat. solution | 3.5 mol dm-3 | sat. solution |
15 | 0.3362 | 0.254 | 0.2511 | 0.212 | 0.209 |
20 | 0.3359 | 0.252 | 0.2479 | 0.208 | 0.204 |
25 | 0.3356 | 0.250 | 0.2444 | 0.205 | 0.199 |
30 | 0.3351 | 0.248 | 0.2411 | 0.201 | 0.194 |
35 | 0.3344 | 0.246 | 0.2376 | 0.197 | 0.189 |
Silicon was discovered by Jöns Jacob Berzelius (Sweden) in 1824. The origin of the name comes from the Latin word silicis meaning flint. Amorphous form of silicon is brown powder; crystalline form has grey metallic appearance. Solid form unreactive with oxygen, water and most acids. Dissolves in hot alkali. Silica dust is a moderately toxic acute irritant. Silicon makes up major portion of clay, granite, quartz and sand. Commercial production depends on a reaction between sand (SiO2) and carbon at a temperature of around 2200 °C. Used in glass as silicon dioxide (SiO2). Silicon carbide (SiC) is one of the hardest substances known and used in polishing. Also the crystalline form is used in semiconductors.
Thermite is a stoichiometric powdered mixture of iron(II) oxide and aluminium for the reaction
The reaction is highly exothermic and the increase in temperature (over 2500 °C) is sufficient to melt the iron produced. It has been used for localized welding of steel object (e.g. railway lines) in the thermit process. Thermite is also used in incendiary bombs.
Silver/silver-chloride electrode is by far the most common reference type used today because it is simple, inexpensive, very stable and non-toxic. It is mainly used with saturated potassium chloride electrolyte, but can be used with lower concentrations such as 3.5 mol dm-3 or 1 mol dm-3 potassium chloride. Silver/silver-chloride electrode is a referent electrode based on the following halfreaction
Potential vs. SHE / V | ||
---|---|---|
t / °C | 3.5 mol dm-3 | sat. solution |
15 | 0.212 | 0.209 |
20 | 0.208 | 0.204 |
25 | 0.205 | 0.199 |
30 | 0.201 | 0.194 |
35 | 0.197 | 0.189 |
Winkler’s method was once a common method used to determine the dissolved oxygen concentration by titration. Now rarely used due to the accuracy and low price of oxygen meters.
The water sample is first treated with excess manganese(II) sulfate solution and then with an alkaline solution of potassium iodide. The Mn(OH)2 initially formed reacts with the dissolved oxygen. The amount of MnO(OH)2 formed is determined by reaction with iodide ion in acidic solution. The iodine formed may be titrated against standard thiosulfate solution, using starch as an indicator.
Generalic, Eni. "Haber%2C Fritz." Croatian-English Chemistry Dictionary & Glossary. 29 June 2022. KTF-Split. {Date of access}. <https://glossary.periodni.com>.
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