The hardness of minerals is measured on the Mohs Hardness Scale. Reference minerals are used with which any other mineral can be compared. The softest reference mineral is talc (from which talcum powder is produced) and the hardest is diamond. The scale compares the hardness of a given mineral by seeing the effect of scratching it …
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Category:Chemistry
A Quiz Based Upon the CE Mock Chemistry…
The Name’s Bond, Chemical Bond…
Sean (not Connery) mentioned bonds in one of his comments so I thought I would try to explain. It is a little beyond our official syllabus but perhaps you will find it interesting nonetheless…
Useful Products From Air…
The general consensus on the Internet is that oxygen is fractionally less then 21% of dry air. I normally teach 20% because that is one fifth (which is pleasing) and allows a whole percent for argon. Consensus again puts argon at about 0.9% with carbon dioxide occupying a steadily increasing value just below 0.04%. Nitrogen …
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Crude Oil…
Crude oil is one of the three main fossil fuels (along with natural gas and coal) – it is also known as petroleum. It is formed from millions of microscopic plants and animals that have been buried in sediment and subjected to high temperatures and pressure for a long time. It consists of a mixture …
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Gypsum…
Calcium sulphate, commonly known as gypsum, is a soft mineral formed when calcium hydroxide (lime) reacts with sulphuric acid. It is moderately soluble but unlike most other salts it is more soluble in cold water than in hot water. Its chemical formula is CaSO4.2H2O – as it has two molecules of water associated with it in its …
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Cadbury’s Creme Egg…
There is a great channel on YouTube called the Periodic Table of Videos. They are led by the crazy-haired chemistry professor Sir Martyn Poliakoff at Nottingham University. They started out attempting to make a video about every element on the Periodic Table. They have since branched out into all manner of delightful demonstrations. Inspired by …
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Lime…
There is a group of compounds containing the metal element calcium that includes the word “lime” in their common name. They can be neatly demonstrated through the limestone cycle. Limestone (marble, chalk) has the chemical name calcium carbonate. When it is heated it decomposes (like all carbonates) releasing carbon dioxide and leaving calcium oxide behind. Calcium oxide is …
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Soda…
There is a group of compounds based around the element sodium whose common names all include the word soda. There are lots of other sodium compounds such as sodium chloride that don’t get soda in their name – although glass made with sodium oxide is called soda glass. Sodium bicarbonate is a soluble, white compound with …
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Breaking The Bonds…
An endothermic reaction is one that gets colder as it proceeds; unlike an exothermic reaction which releases heat as it progresses. It all depends upon the bonds between the atoms in the reactants and the products. The first thing to say is that during a chemical reaction, exactly the same atoms appear in the products …
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