The alkali metals are so called because reaction with water forms alkalies i. Potassium imparts a lavender colour to a flame, and its vapour is green. Potash mine at Esterhazy, Sask. The waste liquors from certain saltworks may contain up to 40 grams per litre of potassium chloride and are used as a source of potassium. K Most potassium is present in igneous rocks, shale, and sediment in minerals such as muscovite and orthoclase feldspar that are insoluble in water; this makes potassium difficult to obtain. Molten KCl is continuously fed into a packed distillation column while sodium vapour is passed up through the column. Efforts to devise a scheme for commercial electrolytic production of potassium have been unsuccessful because there are few salt additives that can reduce the melting point of potassium chloride to temperatures where electrolysis is efficient. There is little commercial demand for potassium metal itself, and most of it is converted by direct combustion in dry air to potassium superoxide, KO2, which is used in respiratory equipment because it liberates oxygen and removes carbon dioxide and water vapour. It also can be formed by oxidation of potassium amalgam with dry air or oxygen. The metal is also used as an alloy with sodium as a liquid metallic heat-transfer medium.
READ MORE Properties, occurrence, and uses Potassium metal is soft and white with a silvery lustre, has a low melting point , and is a good conductor of heat and electricity. Potassium imparts a lavender colour to a flame, and its vapour is green. Potash mine at Esterhazy, Sask.
Radiometric dating is a means of determining the “age” of a mineral specimen by determining the relative amounts present of certain radioactive elements. By “age” we mean the elapsed time from when the mineral specimen was formed. , is equal to the amount of potassium in the sample, divided by the sum of potassium in the sample plus.
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(K/Ar) Potassium Argon Dating Techniques I
Departures from this assumption are quite common, particularly in areas of complex geological history, but such departures can provide useful information that is of value in elucidating thermal histories. A deficiency of 40 Ar in a sample of a known age can indicate a full or partial melt in the thermal history of the area. Reliability in the dating of a geological feature is increased by sampling disparate areas which have been subjected to slightly different thermal histories.
May 09, · To clarify, potassium has an advantage over carbon 14 in dating fossils because it has a very long half-life. It is not used to date fossils directly, but rather by dating associated rocks. If the types of rocks in which potassium occurs are not found in the strata in which the fossils are found, it can be used to date the strata above and Status: Resolved.
How accurate are carbon-dating methods? All methods of radioactive dating rely on three assumptions that may not necessarily be true: Rate of Decay It is assumed that the rate of decay has remained constant over time. This assumption is backed by numerous scientific studies and is relatively sound. However, conditions may have been different in the past and could have influenced the rate of decay or formation of radioactive elements.
Evolutionists assume that the rate of cosmic bombardment of the atmosphere has always remained constant and that the rate of decay has remained constant. Thus radioactive dating relies purely on assumptions.
Potassium, Chemical Element
Potassium—argon dating[ edit ] Decay scheme Potassium is especially important in potassium—argon K—Ar dating. Argon is a gas that does not ordinarily combine with other elements. So, when a mineral forms — whether from molten rock , or from substances dissolved in water — it will be initially argon-free, even if there is some argon in the liquid. However, if the mineral contains any potassium, then decay of the 40K isotope present will create fresh argon that will remain locked up in the mineral.
Potassium decays with a half-life of million years, meaning that half of the 40 K atoms are gone after that span of time. Its decay yields argon and calcium in a ratio of 11 to Its decay yields argon and calcium in a ratio of 11 to
These are K-Ar data obtained on glauconite, a potassium-bearing clay mineral that forms in some marine sediment. Woodmorappe fails to mention, however, that these data were obtained as part of a controlled experiment to test, on samples of known age, the applicability of the K-Ar method to glauconite and to illite, another clay mineral. He also neglects to mention that most of the 89 K-Ar ages reported in their study agree very well with the expected ages. Evernden and others 43 found that these clay minerals are extremely susceptible to argon loss when heated even slightly, such as occurs when sedimentary rocks are deeply buried.
As a result, glauconite is used for dating only with extreme caution. The ages from the Coast Range batholith in Alaska Table 2 are referenced by Woodmorappe to a report by Lanphere and others Whereas Lanphere and his colleagues referred to these two K-Ar ages of and million years, the ages are actually from another report and were obtained from samples collected at two localities in Canada, not Alaska.
There is nothing wrong with these ages; they are consistent with the known geologic relations and represent the crystallization ages of the Canadian samples. The Liberian example Table 2 is from a report by Dalrymple and others These authors studied dikes of basalt that intruded Precambrian crystalline basement rocks and Mesozoic sedimentary rocks in western Liberia.
Carbon, Radiometric Dating
Carbon , Radiometric Dating and Index Fossils Carbon dating is used to determine the age of biological artifacts up to 50, years old. This technique is widely used on recent artifacts, but educators and students alike should note that this technique will not work on older fossils like those of the dinosaurs alleged to be millions of years old. This technique is not restricted to bones; it can also be used on cloth, wood and plant fibers.
Carbon dating has been used successfully on the Dead Sea Scrolls, Minoan ruins and tombs of the pharaohs among other things.
Argon may be incorporated with potassium at time of formation. This is a real problem, but it is easily overcome either by careful selection of the material being dated or by using 40 Ar/ 39 Ar dating instead of K-Ar dating. In the case of the claim about recent lava yielding dates that are millions.
Wujing Zongyao , Four Great Inventions , List of Chinese inventions , and Heilongjiang hand cannon Based on a 9th-century Taoist text, the invention of gunpowder by Chinese alchemists was likely an accidental byproduct from experiments seeking to create elixir of life. In the following centuries various gunpowder weapons such as bombs , fire lances , and the gun appeared in China. A slow match for flame throwing mechanisms using the siphon principle and for fireworks and rockets is mentioned.
However by the Song court was producing hundreds of thousands of fire arrows for their garrisons. The first proto-guns, known as “fire lances”, were first recorded to have been used at the siege of De’an in by Song forces against the Jin. By some fire lances were firing wads of bullets. From the Huolongjing ca. The oldest known depiction of rocket arrows, from the Huolongjing. The right arrow reads ‘fire arrow,’ the middle is an ‘arrow frame in the shape of a dragon,’ and the left is a ‘complete fire arrow.
Considered to be a pseudo-explosive. The top item is a through awl and the bottom one is a hook awl. A fire lance as depicted in the Huolongjing ca.
Go Back Argon-Argon Dating and the Chicxulub Impact In the early s there was an intense controversy about the association of the Chicxulub Crater of the Mexican Yucatan Peninsula with the extinction of the dinosaurs in the period about 65 million years ago. The Cretaceous-Tertiary boundary in the geological age scale was associated with an iridium-rich layer which suggested that the layer was caused by an impact with an extraterrestrial object. Because that time period, commonly referred to as the K-T boundary, was associated with the extinction of vast numbers of animals in the fossil record, much effort was devoted to dating it with potassium-argon and other methods of geochronology.
The time of 65 million years was associated with the K-T boundary from these studies. Other large impact craters such as the Manson crater in Iowa dated to 74 My were examined carefully as candidates for the cause of the extinction, but none were close to the critical time. Chicxulub was not so obvious as a candidate because much of the evidence for it was under the sea.
This dating method is based upon the decay of radioactive potassium to radioactive argon in minerals and rocks; potassium also decays to calcium Thus, the ratio of argon and potassium and radiogenic calcium to potassium in a mineral or rock is a measure of the age of the sample.
The Radiometric Dating Game Radiometric dating methods estimate the age of rocks using calculations based on the decay rates of radioactive elements such as uranium, strontium, and potassium. On the surface, radiometric dating methods appear to give powerful support to the statement that life has existed on the earth for hundreds of millions, even billions, of years. We are told that these methods are accurate to a few percent, and that there are many different methods.
We are told that of all the radiometric dates that are measured, only a few percent are anomalous. This gives us the impression that all but a small percentage of the dates computed by radiometric methods agree with the assumed ages of the rocks in which they are found, and that all of these various methods almost always give ages that agree with each other to within a few percentage points.
Since there doesn’t seem to be any systematic error that could cause so many methods to agree with each other so often, it seems that there is no other rational conclusion than to accept these dates as accurate. However, this causes a problem for those who believe based on the Bible that life has only existed on the earth for a few thousand years, since fossils are found in rocks that are dated to be over million years old by radiometric methods, and some fossils are found in rocks that are dated to be billions of years old.
If these dates are correct, this calls the Biblical account of a recent creation of life into question.