Chem. Revision: WHAT IS A MOLE????

Question

I'm revising for a chamistry test but what is the mole of a subtance, what is it used for, and how do I work it out?

Answer 1

A mole is the SI unit of amount of substance.

Think of the word "pair": a pair of gloves, a pair of earrings... The word "pair" tells you that there are two of 'things' under consideration regardless of what they are.

In the same way the word "mole" tells you there is a specific number of 'things' - in this case a very big number of things equal to approximately 6.022 x 10^23 !

Why use this big number? Well it pops up all the time in chemistry and related sciences. One mole has the same magnitude as Avogadro's Number which can be related to other fundamental constants such as the Boltzmann and ideal gas constant. One mole is also the number of C-12 atoms in 0.012 kg of pure carbon.

Answer 2

Think of it this way. If you wanted to compare piles of footballs and table-tennis balls, you'd want to know how many were in each pile, not the weight of the pile. If there were equal numbers, clearly the pile of footballs would weigh more.

Same with molecules. The mole is the quantity of whatever-it-is that contains a certain number of atoms (see other answerers for the actual number). So a mole of hydrogen (H2 = a light molecule) weighs a lot less than a mole of lead sulphate (for instance). The mole is not a fixed mass, therefore, but a different mass for each substance according to its molecular weight.

When things react chemically, it's the numbers of different molecules that matter. That's why the mole is important in chemistry.

Answer 3

Hi. http://www.answers.com/MOLE?cat=health&gwp=13 The site gives an explanation.
From the site "A mole is much like "a dozen" in that both are absolute numbers (having no units) and can describe any type of elementary objects, although the mole's use is usually limited to measurement of subatomic, atomic, and molecular structures."

Answer 4

Safely & Permanently Remove Moles, Warts and Skin Blemishes

Answer 5

a mole or more usually a gram mole is a certain amount of molecules of a material( molecule)

the unit is the molecule weight multiplied with one gram.

Hydrogen H2 has the molecule weight 2, 1mole= 2gram
Oxygen O2 has the molecule weight 16. 1mole=16gram.

The number of molecules are the same.

Answer 6

a mole refers to how many atoms of hydrogen you would need to have one gram. but it is works with other things too. it basically means if the atomic mass of lets say U-238 is 238, then if you have 238 grams of uranium, you have 6.022*10^23, but if you have 4 grams of say He, you also have 6.022*10^23 atoms of helium. it is used in balancing chemical equations.

Answer 7

the mole is a unit that links micro (atoms) to macro (molecules) and vice versa.
instead of dealing with 10^23 atoms of Cl or Na, it is easier to deal with 1 mole of Cl or Na, unless you really feel confident with large numbers and how to sum and multiply them...

Good luck for your revisions and your exam !!

Answer 8

less complicated way fifty six x 2 = 112 sixteen x 3 = forty 8 = one hundred sixty (keep in mind that) fifty six x 2 = 112 112 ____ x 240 = 168 one hundred sixty So its in certainty: mass of two Fe (112) divided by using Mass of Fe2 O3 (one hundred sixty) then prolonged by using 240 tonnes

Answer 9

a mole is a certain amount of molecules 6.023 x 10^23 in an entity

Answer 10

mole:is an amount of substancethat contains as many elementary entities as there are atoms in exactly 12 g of carbon- 12. It contains Avogadro's number,N(6.02x10^23 )of atoms, molecules,or formula units.
No. moles = mass(g)/ molar mass