Gold is also weighed in carats. A carat is defined as one fifth of a gram, or 200 milligrams.
Gold is seldom used in a pure form. The metal is too soft. It would bend or break if used pure. Instead, it is used in combination with other metals called alloys. An alloy is a mixture of two or more metals. The mixture has properties different from those of the individual metals.
The amount of gold in an alloy is expressed in carats. Pure gold metal (mixed with no other metal) is said to be 24-carat gold. An alloy that contains 20 parts of gold and 4 parts of silver is 20-carat gold. The "20-carat" designation means the alloy contains 20 parts of gold and 4 parts of something else (silver, in this case).
Gold stored in a national bank can be 24-carat gold. It is never used for any practical purpose. But gold used for any real application is almost always less than 24 carats. It must include other metals that make it stronger and tougher.
Gold ores can also be treated with potassium cyanide (KCN) or some other kind of cyanide. The gold combines with the cyanide to form a new compound, gold cyanate. The gold cyanate is then treated with an active metal, such as zinc. The active metal replaces gold in the compound, leaving pure gold.
Read more: http://www.chemistryexplained.com/elements/C-K/Gold.html#ixzz3IxvW0Qhs
Gold is also weighed in carats. A carat is defined as one fifth of a gram, or 200 milligrams.
Gold is seldom used in a pure form. The metal is too soft. It would bend or break if used pure. Instead, it is used in combination with other metals called alloys. An alloy is a mixture of two or more metals. The mixture has properties different from those of the individual metals.
The amount of gold in an alloy is expressed in carats. Pure gold metal (mixed with no other metal) is said to be 24-carat gold. An alloy that contains 20 parts of gold and 4 parts of silver is 20-carat gold. The "20-carat" designation means the alloy contains 20 parts of gold and 4 parts of something else (silver, in this case).
Gold stored in a national bank can be 24-carat gold. It is never used for any practical purpose. But gold used for any real application is almost always less than 24 carats. It must include other metals that make it stronger and tougher.
Gold ores can also be treated with potassium cyanide (KCN) or some other kind of cyanide. The gold combines with the cyanide to form a new compound, gold cyanate. The gold cyanate is then treated with an active metal, such as zinc. The active metal replaces gold in the compound, leaving pure gold.
Read more: http://www.chemistryexplained.com/elements/C-K/Gold.html#ixzz3IxvW0Qhs
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