Hello everyone today we will discuss about "Mole Concepts" so in this video our focus will be to learn all formulas tips and tricks that will help us in solving numericals. So lets start our discussion with simplified definition of these 3 terms Atomic Mass, Molecular Mass and Molar Mass ATOMIC MASS is mass of 1 atom. The mass of 1 single atom. 2. Molecular Mass - which is mass of a single molecule Next Term is Molar Mass which is Mass of 1 mole in another word it is mass of 6.022 x 10^23 particles so that's what makes it different from Atomic and Molecular Mass Atomic and Molecular Mass is about (mass of 1 particle) while Molar Mass is about Mass of (6.022 x 10^23 particles) Now, these particles can be atoms or molecules. if we're talking about of 6.022 x 10^23 (atoms) then mass we're talking about is "Gram Atomic Mass" and if we talk about 6.022 x 10^ 23 (Molecules) then it'll be (Gram Molecular Mass) So, molar mass has 2 category 1st - Gram Atomic Mass which is abbreviated as GAM and another is Gram Molecular Mass which is abbreviated as GMM Now let's considered an example of Nitrogen You may have noticed that the mass of Nitrogen can be written as 14u and sometimes 14 grams So, what is the difference between these two? so when we are writing 14u in that case we are talking about Atomic Mass mass of 1 atom and when we write 14 gram then we are talking about Gram Atomic Mass which is mass of 1 mole atoms So, it is necessary to make distinction between these two till now you might be aware of some basic atomic masses like carbon has atomic mass 12u nitrogen's atomic mass is 14u oxygen 16u but you might be wondering do we need to learn all 118 elements atomic masses and answer is no. You don't need to. Out of 118 elements, there are 28-30 elements whose atomic mass should be remembered so I am adding those atomic masses here I will suggest you to pause and write it down So, Do we need to cram this list? No, not at all. As you practice the numericals of the mole concept you will gradually learn all these atomic masses and the elements that are not in this list like Thorium, Zicronium, Tungsten you will be given their atomic masses if they come now the next thing is calculating - molecular mass of Water, Calcium Hydroxide and Na2SO4 .10 H2O If you can calculate the molecular mass of these 3 molecules then you can calculate molecular mass of any type let's start with water to get the molecular mass of water we need to add mass of each atom present in this molecule hydrogen's atomic mass is 1 oxygen's atomic mass is 16 so in case of (water), we have (2 hydrogen) and (1 oxygen) so water molecular mass will be 2 x 1 + 16 and it will be equal to 18 and because we're talking about molecular mass so we will write 18u next is calcium hydroxide so initially it is important to understand its structure (Calcium Hydroxide) has (1 Calcium) atom and (2 Hydroxide) ions the mass of calcium is 40 so we will write 40 and (hydroxide) ion will be (16 + 1) and because we have 2 (hydroxide) ions so we will write 2 (16 + 1) and on calculation. we will get 74u now Na2SO4. 10 H2O Contains 2 (Sodium) 1( Sulphur) 4 (oxygen) and 10 (Water) molecule sodium has atomic mass 23. Sulphur's mass is 32 oxygen 16 and water 18 so its molecular mass will be (2 x 23 + 32 + 4 X 16 ) + 10 x 18 so, you can calculate it by yourself what is the result. put it in the comments section so basically you need to understand molecular structure if you are saying Na2SO4 10H2O it means we have 10 (H2O) molecule and not 10 (H2) and 1 (O) molecule in case of water - mass can be written as 18u or 18g when it's 18u - it is molecular mass and when it is 18g - then it is gram molecular mass Now let's see relation between 1 mole - molar mass - molar volume 1 mole as we know it is 6.022 x 10^23 particles In case of (atom) one mole will be 6.022 x 10^23 (atoms) and this mass is called Gram Atomic Mass next is molecule. in case of (molecule) 1 mole = 6.022 x 10^23 (molecules) and this mass is called Gram Molecular Mass Now relation between mole and molar volume this relation is used for gaseous particle in case of gases 1 mole = 6.022 x 10^23 (gaseous particle) and and the (volume of these particles) is always equal to 22.4 litre and this volume is called Molar volume as we know gas volume changes with changing pressure and temperature So, 1 mole = 22.4 L at Standard pressure and temperature condition (STP condition) and STP condition mean pressure should be (1 atmosphere) and temperature should be (273 Kelvin) No matter which gas we are talking about Carbon Dioxide , Ammonia, Sulphur Dioxide, Sulphur trioxide 1 mole is always 22.4 L at STP condition So, here we have 4 formulas that will help you solve any kind of mole concept numericals Now, let's understand each formula one by one first one is for Atomic Substance so In case of atomic substance the formula for (number of moles) is number of moles = given mass / gram atomic mass in short form we can write it as n = m / GAM Next one is for molecule here, no of moles = (given mass) / (gram molecular mass) and in short form it is written as n = m / GMM and if we talk about gaseous substance then it will be number of moles = (volume at STP conditions in L) / 22.4 L and in short form it is written as n = V / 22.4 liters in case you are given number of particles like (number of atoms) (number of molecules) or (number of ions) then use this formula (number of moles) = (number of particles) / (Avogadro number) in this case Avogadro Number is nothing but 6.022 x 10^23 particle so in short we will write it as n = N / Na Now you will learn how to use this formula so let's do some numericals our first question is to calculate (number of moles) in 392g of H2SO4 in this question we want to calculate (number of moles) and we're dealing with (molecular substance) So, we'll us n = m / GMM here given mass is 392g So, first of all - calculate Gram Molecular Mass So, Gram Molecular Mass of H2SO4 will be 2 x 1 + 32 + 4 x 16 and on calculating it we will get 98 g so, we know m and GMM. We will put it here and calculate (number of moles) Next question - calculate (number of moles) in 44.8 liters of carbon dioxide at STP so we will use n = (V at STP) / 22.4 now given volume at (STP condition) = 44.8 L So, just put it here and calculate (number of moles) so that's how we convert (grams to moles ) (litre to moles) in some question, we need to convert (moles to grams) and (moles to litres) in that case, same formula will be used. So, let's understand formula. n = m / GMM if you are given (moles) and you want to calculate (mass of the substance) m is given here and we know how to calculate Gram Molecular Mass you can put their values, then you can calculate the mass of the substance now next question calculate (number of atoms) of the (constituent element) in 53 gram of Na2CO3 in this question, we have to find out that how many (sodium atom) (carbon atom) (oxygen atom) are in 53 g of Na2CO3 So, we've to find out number of moles of all in this question Step 1 - Calculate (number of moles) Step 2 - use it to calculate (number of molecules) in Na2CO3 Next step use Number of Na2CO3 (molecule) to calculate (number of atoms) so let's calculate number of moles given mass is 53g on calculation you will get (gram molecular mass) = 106g so, n = m / GMM m = 53 and GMM = 106 so, on putting it. we'll get 0.5 and we know that 1 mole = 6.022 x 10^23 molecules So, 0.5 mole = 0.5 x 6.022 x 10^23 molecules so, we'll get 3.011 x 10^23 molecules Now, next step in 1 molecule of (Na2CO3), there are 2 (Na atoms) (1 carbon atom) and (3 oxygen atom) so in (1 molecule) of Na2CO3, we have (2 Na atom) but here, we've 3.011 x 10^23 molecules So, Na atom = 2 x (3.011 x 10^23 ) 1 Na2CO3 molecule have 1 carbon atom So, (3.011 x 10^23 ) molecules will have (3.011 x 10^23 ) carbon atoms Similarly, 1 Na2CO3 molecule has 3 Oxygen Atoms So, Na2CO3 = 3.011 x 10^23 molecules So, Oxygen Atom = 3 x (3.011 x 10^23) so here, we calculated (number of molecules) and (number of atoms) from (mass) Now, next question calculate the (number of moles) present in 350 cm3 of carbon dioxide gas at 273 Kelvin and 2 Atmosphere so in this question we have been given the volume and we have to calculate the moles then which formula will be used here? n = (V at STP )/22.4 L But in this question, volume at STP condition is not given STP condition is pressure is equal to 1 atmosphere and temperature is equal to 273 K In the question pressure is 2 atmosphere and temperature 273 K so first of all we need to calculate volume in STP conditions so in order to do so. we need this table P1 = 2 atmosphere V1 = 350 cm3 and T1 = 273K P2 = 1 atm and T2 =273K and our aim is to calculate V2 To find this we have a formula that is "ideal gas equation" which is ( P1V1) / T1 = (P2V2) / T2 Here, we know P1, V1, T1, P2 and T2 we will put it in the formula and calculate V2 so, on calculation V2 = 700 cm3 So, in the formula Volume should be at STP and also in Liters so, our fist work is to convert 770 cm3 in liters so it will be (700/1000) L = 0.7 L Now use this formula and calculate (number of moles) so type of numericals we are doing here will help you to solve any type of mole concepts numericals so let's proceed to the next type of question calculating mass of (one atom) or mass of (one molecule) so we have a question calculate mass of an atom of silver so we can do it within two steps we know that mass of 6.022 x10^ 23 atoms is equal to gram atomic mass of silver in case gram atomic mass is 108 gram so using unitary method mass of one silver atom will be 108 / (6.022 x 10^23) now the rest part is maths so solve it and let us know what is the answer or you can check your answer in the comments section if you think there's something missing let us know in the comments section we can discuss it there and also you can ask your doubts and don't forget to subscribe like share and comment