Can anyone explain what a Mole is?

Question

ok so, i stil dont get what a mole means or is. and what the different conversions between a mole and molarity are and stuff. chemistry has been getting ridiculously confusing.

Answer 1

A mole of something is just Avogadro's Number (6.023 * 10^23) many of it. This is handy because atomic weights are arranged so that a mole of something weighs the same amount in grams as the atomic weight of it. For instance, oxygen gas (O2) has an atomic weight of 32.0, so a mole of oxygen gas weighs 32.0 grams.

Molarity of a solution is just the concentration in moles per litre.

Answer 2

The mole (symbol: mol) is the SI base unit that measures an amount of substance. One mole contains Avogadro's number (approximately 6.022×1023) entities. A mole is much like "a dozen" in that both units can describe any set of elementary objects, although the mole's use is usually limited to measurement of subatomic, atomic, and molecular structures. This is all due to the fact that a mole represents an exceedingly large number of entities.

A mole is the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram (or 12 grams) of carbon-12, where the carbon-12 atoms are unbound, at rest and in their ground state. The number of atoms in 0.012 kilogram of carbon-12 is known as Avogadro's number, and is determined empirically. The currently accepted value is 6.0221415(10)×1023 mol-1 (2002 CODATA).

Molarity (M), on the other hand, denotes the number of moles of a given substance per litre of solution. For instance: 4.0 litres of liquid, containing 2.0 moles of dissolved particles, constitutes a solution of 0.5 M. Such a solution may be described as "0.5 molar." This can be misinterpreted as "0.5 moles of solute per 1.0 liter of solvent", which can be true only if no volume change occurs on adding the solute to the solvent. This is why preparation of a solution of known molarity involves adding an accurately weighed amount of solute to a volumetric flask, adding some solvent to dissolve it, then adding more solvent to fill to the volume mark.

Answer 3

A mole is just a certain number of atoms. Like a dollar is 100 pennies, a mole is 6.02 x 10^23 atoms (atoms are really small, so you have to have a whole bunch of them to make a mole!). A mole of lead will weigh more than a mole of carbon, since each lead atom weighs more than each carbon atom.

Molarity is just how many moles of something are dissolved in a liter of solution. Your piggy bank has 3 dollars in it in pennies - so you know there have to be 300 pennies. If you have a one liter beaker filled with a 3 molar solution, then you know you have 3 moles (or 3 x 6.02x10^23 atoms) in it!

Answer 4

The mole (symbol: mol) is the SI base unit that measures an amount of substance. One mole contains Avogadro's number (approximately 6.022×1023) entities. A mole is much like "a dozen" in that both units can describe any set of elementary objects, although the mole's use is usually limited to measurement of subatomic, atomic, and molecular structures. This is all due to the fact that a mole represents an exceedingly large number of entities.

Answer 5

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Answer 6

Mole = Atomic Mass Unit (AMU) of a MOLECULE expressed in grams

AMU of Carbon (C) molecule = 12
1 mole of carbon = 12 gms

AMU of Oxygen molecule (O2) = 2 x 16 = 32
1 mole of oxygen = 32 gms

AMU of water (H2O) molecule = 1 x 2 + 16 = 18
1 mole of water = 18 gms

Answer 7

A mole is simply a name for a number of things. A pair is two. A dozen is 12. A bakers dozen is 13. Triplets are three. Similarly a mole is 6023 with 20 zeros after it. abbreviated as 6.023 x 10^23.

a mole of donuts is 602,300,000,000,000,000,000,000 donuts. 2 moles of cheeze puffs is 2 x 6.023 x 10^23 cheeze puffs.

For everyday objects, like donuts and cheeze puffs, the term mole can be used but is hard to picture and work with. It is, however, very useful when talking about atoms and molecules because of the huge number of atoms or molecules present in a small amount of matter.

Here's how you use it.

given an amount of mass of a chemical species and the formula for that chemical you can calculate the number of moles of that species (and in turn the number of molecules or atoms) with these equations.

moles = mass of substance / molecular weight of substance
# molecules = moles x 6.023 x 10^23.
example: how many moles and molecules of O2 are present in 8 grams of O2?
well, from the periodic table, the molecular weight of O2 is 32 g/mole
so # moles = 8 grams / (32 g/mole) = 0.25 moles O2
# molecules O2 = .25 * 6.023 x 10^23

concentrations of substances are commonly expressed as molarity or molality or even Normality (in the case of acids and bases).

molarity = moles per liter of solution.
molality = moles per kg solvent
normality = equivalents per liter solution

so say you dissolve 29 grams of NaCl in 1 liter of water.
you would have 29g/ 58g/mole = .5 moles NaCl
you would also have 1 liter water = 1 kg water

molarity is approximately .5 moles/liter = 0.5 molar
(approximately because 29 g NaCl + 1 liter water is slightly bigger than 1 liter. you will understand this later)
molality = 0.5 moles/ kg solvent = 0.5 molal

normality = equivalents per liter and is equal to the number of moles x the number of OH or H groups released per liter of solution. For example HCl has 1 H and equivalents = 1 x moles. H3PO4 (phosphoric acid) has 3 H's per molecule and therefore has 3 x moles H3PO4 equivalents.

example 49 grams phosphoric dissolved in 1 liter of solution has
normality = 3 (equivalents/mole) * 49 g/ (98g/mole) = 1.5 equivalents /liter ie it is 1.5 normal

You can use moles in balanced equations as well eg.
2H2 + 1O2 > 2 H2O
2 moles of hydrogen reacts with 1 mole oxygen to form 2 moles water.

Answer 8

1 mole of a substance contains 6.022 x 10^23 atoms or molecules of that substance. 1 mole of a substance weighs, in grams, the formula mass of the substance. Examples:

1 mole of NH3 has 6.022 x 10^23 molecules and weighs about 17 grams. 1 mole of Cu has 6.022 x 10^23 atoms and weighs about 63.54 grams.

Answer 9

in Greek language mole means a pile of stones in terms of chemistry mole is the concept which contain the same number of entities as there are in carbon-12 isotope

Answer 10

6.0221415 × 10²³ molecules or atoms of a substance is a mole....

Due to different sizes of molecules and atoms
6.0221415 × 10²³ of carbon atoms weighs 12 grams
6.0221415 × 10²³ of oxgen atoms weighs 16 grams

you will find that 12 grams and 16 grams is simply the MOLECULAR NUMBER from your periodic table...

MOLARITY Molarity is the number of moles of solute dissolved in one liter of solution.