## Mole Concept | What is moleA mole concept or mole refers to the amount of a substance that has the same number of particles, atoms or molecules as the number of atoms present in 12 grams of C-12 atom, which is an isotope of carbon. So, the mole concept generally tells the number of atoms or such particles which are equal in number to the atoms present in the 12 grams of C-12. We can say that C-12 atom is taken as a standard to compare the number of atoms or molecules or particles present in the given amount of a substance. The number of particles present in one mole of any substance = 6.023×10 ^{23} particles of that substance. It can be atoms, molecules or any other particles. For example, 1 mole of iron will contain 6.0222 x 10^{23} atoms of iron, similarly, 1 mole of water will contain 6.0222 x 10^{23} molecules of water. So, we can say that as per the definition of mole, the number of atoms present in 1 mole of iron is equal to the number of atoms of C-12 present in 12 grams of C-12.So, the mole concept was introduced as a convenient method to expressing the number of particles in the given amount of a substance at an atomic or molecular level such as one gram of a pure element which contains a large number of atoms. We can say that mole is just like a measurement that comprises two main parts that include the numerical magnitude and the units to express the magnitude. For example, if the mass of a ball is 2 kg, the magnitude is 2 and the unit is kilogram. Similarly, a mole is used as a unit of measurement for measuring the number of elementary entities like atoms, molecules, etc., just like kg is used for measuring weight, and meter is used for measuring length. Furthermore, The mole concept was ^{23} number of particles just like a pair represents 2 and a dozen represents 12. For example, a boy goes to a shop and ask for Avogadro's number of chocolates then he wants 6.0222 x 10^{23} chocolates. However, it has no practical use in daily life. So, it is introduced to represent quantities related to atoms, molecules, electrons, etc.The number 6.0222 x 10 n = N/N n= number of moles of the substance N= total number of particles in the given sample N The Furthermore, the number of moles of a molecule may not be equal to the number of moles of its constituting elements. For example, one mole of carbon dioxide contains N
Furthermore, the atomic mass unit and mole both are based on the same reference substance C 12, so, the molar mass of a substance in gram is numerically equal to its atomic mass in amu. ## Let us solve some numerical to understand the mole concept## Calculate the number of moles in the following cases;
1 mole of He = 66.0222 x 10 The atomic mass of 1 He atom = 4 u The mass of 6.0222 x 10 1 mole of He = 4 gram or gram atomic mass of He Now, 4 gram of He = 1 mole So, 52 gram of He will contain = � x 52 = 13 moles
6.022 x 10 So, 12.044 x 10
One molecule of N mass of one N atoms = 14 u So, atomic mass of 2 N atoms (one molecule of nitrogen) = 14 u + 14 u = 28 u Now, one mole of Nitrogen gas will contain 6.0222 x 10 So, 1 mole of N So, 0.5 mole of N gas will contain = 0.5 x 28 g = 14 g of N
Mass of one mole of N atoms or 6.022 x 10 So, mass of 0.5 mole of N atoms will be = ½ x 14 g = 7 g
Mass of one mole of O atoms or 6.022 x 10 So, mass of 2 mole of O atoms will be = 2 x 16 = 32 g
The mass of 6.022 x 10 So, mass of 3.011 x 10
Mass of one molecule of Nitrogen is 28 u as there are two N atoms. So, mass of 6.022 x 10
One mole of Na has 6.022 x 10 Mass of one Na atom is 23 u. Mass of 6.022 x 10 Now, 23 g contains 6.022 x 10 Then, 46 g of Na will contain = (6.022 x 10
Atomic mass of one Oxygen atom = 16 u In O If we take mass in grams, then mass of 1 mole or 6.022 x 10 Now, in 32 g we have 6.022 x 10 So, in 8 g of O
1 mole of carbon contains 6.022 x 10 So, 0.1 mole of carbon will contain = (6.022 x 10
Mass of 1 mole of silver (Ag) = gram atomic mass of Ag = 108 g So, mass of 0.5 mole of silver (Ag) = (108/1) x 0.5 = 54 g
Mass of one molecule of sugar = 12 x12 + 1 x 22 +16 x 11 = 144 + 22 + 176 = 342 u One mole of sugar contains 6.022 x 10 Mass of 6.022 x 10 So, mass of 0.5 mole of sugar is = 342 x 0.5 = 171 g ## Mole concept formulasThere are lots of formulas in mole concept that can be used to solve numerical involving mole concept, such as;
Number of moles = given mass in grams/ molar mass in g/mol n = m / M, where m is mass given in grams and M is molar mass
Mass in grams = number of moles x molar mass g/mol m = n x M, where n is number of moles and M is molar mass
Number of atoms or molecules = number of moles x Avogadro's number N = n x N iv) To convert given number of atoms or molecules into moles Number of moles = given number of atoms or molecules / Avogadro's number n = N/ N ## Let us see some |