What is koh: Definition and 11 Discussions

The Koh-i-Noor ( KOH-in-OOR; from Persian for 'Mountain of Light'), also spelled Kohinoor and Koh-i-Nur, is one of the largest cut diamonds in the world, weighing 105.6 carats (21.12 g). It is part of the Crown Jewels of the United Kingdom. The diamond is currently set in the Crown of Queen Elizabeth The Queen Mother.
There are multiple conflicting legends on the origin of the diamond. However, in the words of Theo Metcalfe there is 'very meager and imperfect' evidence of the early history of the Koh-i-Noor before the 1740s, that can directly tie it to any ancient diamond. There is no record of its original weight, but the earliest attested weight is 186 old carats (191 metric carats or 38.2 g). The first verifiable record of the diamond comes from a history by Muhammad Kazim Marvi of the 1740s Invasion of Northern India. Marvi notes that the Koh-i-Noor as being one of many stones on the Mughal Peacock Throne that Nader Shah looted from Delhi. The diamond then changed hands between various empires in south and west Asia, until being given to Queen Victoria after the British East India Company's annexation of the Punjab in 1849, during the reign of the then eleven-year-old Maharaja of the Sikh Empire Duleep Singh, who ruled under the shadow influence of the Company ally Gulab Singh the 1st Maharaja of Jammu and Kashmir, who had previously possessed the stone.Originally, the stone was of a similar cut to other Mughal-era diamonds, like the Daria-i-Noor, which are now in the Iranian Crown Jewels. In 1851, it went on display at the Great Exhibition in London, but the lackluster cut failed to impress viewers. Prince Albert, husband of Queen Victoria, ordered it to be re-cut as an oval brilliant by Coster Diamonds. By modern standards, the culet (point at the bottom of a gemstone) is unusually broad, giving the impression of a black hole when the stone is viewed head-on; it is nevertheless regarded by gemologists as "full of life".Since arriving in the UK, it has only been worn by female members of the family. Victoria wore the stone in a brooch and a circlet. After she died in 1901, it was set in the Crown of Queen Alexandra. It was transferred to the Crown of Queen Mary in 1911, and finally to the Crown of Queen Elizabeth the Queen Mother in 1937 for her coronation.
Today, the diamond is on public display in the Jewel House at the Tower of London. The governments of India, Iran, Pakistan, Afghanistan, and even the Taliban insurgency have all claimed ownership of the Koh-i-Noor, demanding its return ever since India gained independence from the British Empire in 1947. The British government insists the gem was obtained legally under the terms of the Last Treaty of Lahore and has rejected the claims.

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  1. pmason61

    Conversion from dry KOH to liquid 45% KOH

    Hoping to get my assumptions and math verified here. We have a process that requires 42 lbs of dry flake KOH (90% purity). Looking to find the equivalent volume (liters) of 45% liquid KOH (11.1 molar strength) - being extracted from a 55 gallon drum. 1 liter of liquid KOH has 11.1 x 56...
  2. Asontg

    Potassium Chloride Electrolysis

    Hi everyone, I'm new on this forum, I make potassium soap but there were changes in the regulations in my country (Argentina) and now there's a lot of slow bureaucracy needed to buy chemicals like KOH (the regulations are industry-focused but are affecting small businesses like mine) so...
  3. J

    KOH Solubility: Negative Heat of Solution Explained

    This is a quick question. My textbook lists the heat of solution of KOH as a negative number, and thus the solubility of KOH decreases as temperature is raised. Word for word, my book says "Negative heat of solution: The solute solubility decreases with rising solution temperature". But this...
  4. T

    Reaction of acetic acid (CH3COOH) with potassium hydroxide (KOH)

    Homework Statement Balance the following equation and write the corresponding ionic and net ionic equation (if appropriate): CH_{3}COOH _{(aq)}+ KOH _{(aq)} \rightarrow Homework Equations None as far as I know. The Attempt at a Solution I wrote: CH_{3}COOH _{(aq)}+ KOH...
  5. A

    How to precipitate Al(OH)3 from potassium aluminate in KOH?

    How to precipitate aluminium hydroxide Al(OH)3 from potassium aluminate K2Al2O4 which is dissolved in potassium hydroxide KOH? Are there any seeding agents which could be used? What will be the resulting compound(s) (ions) of the reaction(s)? Alternatively other methods how to make aluminium...
  6. P

    KOH. the structural formula for it

    Is it valid to express KOH in this way (see attached image)? I wasn't sure if structural formulae are applicable to ions. The single bond to me denotes a covalent bond, which isn't applicable to the ionic compound KOH, is it?
  7. S

    [H+] and pH of 100 mM solution of KOH

    Homework Statement What is [H+] and pH for a 100 mM solution of KOH The Attempt at a Solution This seems very simple..its only 2 marks but I don't know what I'm doing wrong. I understand KOH will dissociate into K+ and OH- pOH=-log(OH) ? ph + pOH = 14 p[OH]=-log[100x10^-6?]...
  8. Topher925

    Need help understanding KOH + Al2O3 reaction

    Sorry if this is a dumb question but I'm an ME and am only now starting to get a grip on chemistry. If I have ruby (Cr:Al2O3) in a humidified air environment that contains KOH, my limited chemistry knowledge tells me that the alkali, KOH, will react with the ruby. However, I can't figure out...
  9. O

    Titration of HBrO: Calculating pH of KOH Volumes

    Homework Statement Consider the titration of 20.0mL of a 0.100 M solution of HBrO, a weak acid (Ka=2.5x10-9) with 0.200 M KOH. Calculate the pH of the following volumes of KOH. a. 0.00mL b. 5.00mL c. 10.00mL d. 30.00mL Homework Equations pH=pKa +log [base]/[acid] The Attempt...
  10. L

    Calculating pH Change in C6H5COOH Solution with KOH Addition

    Question: Calculate the change in pH of a 0.400 M C6H5COOH solution when 100.0 ml of a 2.50 M KOH solution is added to 1.000 L of C6H5COOH. For C6H5COOH, Ka = 6.46 X 10^-5. Work Done So Far: We're to determine the change in pH, thus we'll need to find the original pH. Ka = 6.46 X...
  11. N

    Request advice on right application of NaOH or KOH

    I work in a restauant and use KOH and NaOH as degreasers. Will these damage our septic system if I put them down the drain? Would it be better to send them to the landfill? Is one less harmful to the environment than the other? Personally I use them as spareingly as possible but I know...