Mole (unit) 

• atoms
• molecules
• ions
• electrons
• other particles
• specified groups of such particles

See also chemistry and physics

Put more colloquially, the mole is a convenient way of counting large numbers of particles. The number defined above ("as many elementary entities . . . ") is known as Avogadro's number, and is approximately 6.02 x 10²³. If you are dealing with this many atoms or eggs or artichoke hearts, then you have a mole of atoms or eggs or artichoke hearts. If you have half this number of such entities, then you have half a mole of such entities.

A mole of atoms or molecules is also called a 'gram atom' or 'gram molecule', respectively.

Moles and calculations

Moles are very useful in chemical calculations, as they enable the calculation of yields and other values when dealing with particles of different mass. In this example, moles are used to calculate the mass of CO₂ given off when 1g of ethane is burnt. The formula involved is:

3.5O₂ + C₂H₆ → 2CO₂ + 3H₂O

Here 3.5 moles of oxygen reacts with 1 mole of ethane, to give 2 moles of CO₂ and 3 moles of H₂O. Notice that the amount of moles doesn't need to balance on either side of the equation. This is because a mole doesn't count mass or the number of atoms involved, simply the number of individual particles. In our calculation it is first necessary to work out the number of moles of ethane that has been burnt. The mass of one mole of a substance is defined as being equal to its atomic or molecular mass. The atomic mass of hydrogen is 1g, and the atomic mass of carbon is 12g, so the molecular mass of C₂H₆ is: 2*12 + 6*1 = 30g. One mole of ethane is 30g. The amount burnt was 1g, or 1/30th of a mole. The molecular mass of CO₂ (when the atomic mass of carbon is 12g, and oxygen is 16g) is: 2*16 + 12 = 44g, so one mole of carbon dioxide is 44g. From the formula we know that:

• 1 mole of ethane gives off 2 moles of carbon dioxide.

We also know the masses of a mole of both ethane and carbon dioxide, so:

• 30g of ethane gives off 2*44g carbon dioxide.

It is necessary to multiply the mass of carbon dioxide by two because two moles are produced. However, we also know that just 1/30th of a mole of ethane is burnt was burnt. Again:

• 1/30th of a mole of ethane gives off 2*1/30th of a mole of carbon dioxide.

So finally

• 30*1/30 g ethane gives off 44*2/30 g of carbon dioxide = 2.93g

From "Mol":

A measure of quantity used in chemistry (pronounced "mole"). Weight isn't a very useful unit in chemistry because reactions take place between atoms (two hydrogen atoms and one oxygen atom makes one molecule of water) which have very different weights (one oxygen atom weighs almost 16 times as much as a hydrogen atom). The numbers of atoms in a reaction is also quite useless, because they are simply too large. Just one milliliter of water contains over 30,000,000,000,000 billion molecules.

1 Mol = 6.02214*10²³ parts. (This number is called Avogadro's number)

Example: The relative atomic mass of nitrogen is 14u. The rule is "mol times atomic mass equals grams": 1 mol times 14u equals 14 grams

The number of parts in a mol was originally chosen so that 14 grams of nitrogen make up one mol; however, the definition of the mol and the atomic mass unit are currently set such that one mol of carbon, which has a relative atomic mass of 12u, is exactly 12 grams. (This does lead to a small difference, because of Strong interaction)

See also: Mole Day

The events of this war.html">war are given in the following chapter, Constantinople, and with it win an opening to the Mediterranean, Asiatic conquest and the expansion of empire over the great territory, including the immense area of Siberia and the realms in China in 1900 increased the Russian dominion in Asia, giving seaport of Port Arthur. It began to appear as if this whole and Japan. THE RUSSO-JAPAN WAR The danger of this roused Japan to action.html">action. When it became evident in Manchuria, and showed signs of an aggressive movement against 1904, Japan withdrew her minister from St. Petersburg and three attacked the Russian fleets at Chemulpo and Port Arthur and 13th admiral.html">admiral Togo drove back the Russian fleet, its flagship, the admiral. On land the Russians were defeated at the battle.html">battle of the bombarded. Battles followed in rapid succession, with victory for battle on the heights of Nan-Shan and captured the Russian port where was fought one of the great battles of the war, lasting when the armies met in September, and remained face.html">face.html">face to face until decisive action took place, the armies numbering nearly 500,000 second retreat of the Russians. There were no further engagements face for months in a long line south of.

 On wordlookup.net  

All is still licensed under the GNU FDL.
It uses material from the wikipedia.