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Arsenic was known to be poisonous during the Victorian era. [103] Beginning in about 3000 BC arsenic was mined and added to copper in the alloying of bronze, but the adverse health effects of working with arsenic led to it being abandoned when a viable alternative, tin, was discovered. [104]
The Marsh test treats the sample with sulfuric acid and arsenic-free zinc. Even if there are minute amounts of arsenic present, the zinc reduces the trivalent arsenic (As 3+). Here are the two half-reactions: Oxidation: Zn → Zn 2+ + 2 e − Reduction: As 2 O 3 + 12 e − + 6 H + → 2 As 3− + 3 H 2 O. Overall, we have this reaction:
Arsenic is a common n-type dopant in semiconductor electronic devices. It is also a component of the III–V compound semiconductor gallium arsenide. Arsenic and its compounds, especially the trioxide, are used in the production of pesticides, treated wood products, herbicides, and insecticides. These applications are declining with the ...
James Marsh (2 September 1794 – 21 June 1846) was a British chemist who invented the Marsh test for detecting arsenic. Born in Kent, he was working as a labourer in Woolwich in the late 1810s and early 1820s, before joining the Royal Artillery. [1] He was married to Mary, and had four children, two of whom died in infancy. [2]
The Lower Paleolithic period lasted over 3 million years, during which there many human-like species evolved including toward the end of this period, Homo sapiens.The original divergence between humans and chimpanzees occurred 13 (), however interbreeding continued until as recently as 4 Ma, with the first species clearly belonging to the human (and not chimpanzee) lineage being ...
The program was the first program to put humans into space, with Yuri Gagarin becoming the first man in space on April 12, 1961, aboard the Vostok 1. [79] Gherman Titov became the first person to stay in orbit for a full day on August 7, 1961, aboard the Vostok 2 . [ 80 ]
Artificial satellites and space probes in the 1950s Year Date Origin Name Launch vehicle Status Description Mass 1957 October 4 Soviet Union: Sputnik 1: Sputnik-PS: Success: The first human-made object to orbit Earth. 83.6 kg (183.9 lb) November 3 Soviet Union: Sputnik 2: Sputnik-PS: Success: The first satellite to carry a living animal, a dog ...
Space exploration is the use of astronomy and space technology to explore outer space. [1] While the exploration of space is currently carried out mainly by astronomers with telescopes , its physical exploration is conducted both by uncrewed robotic space probes and human spaceflight .