the chemistry of yamil [Music] the word Moll It is a term that groups quantities it is very similar to the word dozen to the word ream to the word thick or to the word even a dozen groups 12 units a dozen markers are 12 markers a ream groups 500 sheets if I have two reams Well I have a thousand sheets a thick group 12 dozen if I have two thick I have 24 dozen of those things especially it is used for pencils and a pair groups two units what do I group? well the word mole is used to group atoms and molecules How many atoms does a mole group? Well a mole groups 6.022 times 10 to the 23 particles those particles can be atoms or they can be molecules this number is known as Avogadro's number and it is Avogadro's constant so we can say that one mole of hydrogen is equivalent to 6.022 times 10 to the 23 atoms of hydrogen one mole of carbon dioxide is equivalent to 6.022 times 10 to the 23 carbon dioxide molecules here So now you can understand when we talk about atoms and when we talk about molecules we are going to say the word atoms when it is about a single element we are going to say the word molecules when it is about several elements or several atoms that in this case we have one carbon atom and two oxygen atoms that is why they form molecules also moles can be ions and other chemical species now let's think about something if we have a dozen pencils and each pencil weighs 10 grams then a dozen is equivalent to 120 grams of those pencils now if we had for example a dozen stones and each stone weighed 300 grams then a dozen of those stones would be equal to multiplying 300 by 12 which would be 3600 grams as we see then it is the same amount of pencils and stones but the pencils do not weigh the same as the stones The same thing happens with moles let's observe let's look at the weight of hydrogen hydrogen weighs approximately one atomic mass unit exactly 1.0794 but magnesium weighs 24.3050 magnesium has a greater atomic weight than hydrogen therefore a mole of Magnesium should have more weight greater mass than a mole of hydrogen just as dozens of stones have greater weight than dozens of pencils that tells us that a mole of any atom for example hydrogen or magnesium is equal to the atomic weight expressed in grams atomic weight expressed in grams so then a mole of Magnesium is equal to 24 grams of Magnesium a mole of Mercury is equal to its atomic weight which is 200.59 grams of mercury the same happens with molecules a mole of a molecule is equal to the molecular weight but expressed in grams remember that the molecular weight of any substance has to do with the sum of the atomic weights of the elements that make up that substance for example a mole of water is equal to the molecular weight of water the molar mass of water when we talk about molecular weight we talk about atomic mass unit but when we talk about molar weight or molar mass we talk about grams so let's say that a mole of water is equal to its molar mass that is the mass of hydrogen plus the mass of oxygen then mass of hydrogen which is equal to 1 times 2 atoms is equal to 2 mass of oxygen which is equal to 16 times one atom is equal to 16 we add these two masses and it will give us 18 we can say that one mole of water is equal to 18 grams of water and so on one mole of sulfuric acid is equal to the molar mass of sulfuric acid which we can find like this the mass of hydrogen is 2 by 1 plus the mass of sulfur is 32 by 1 also and the mass of oxygen is 16 by 4 2 by 1 2 + 32 by 1 32 plus 16 by 4 64 this is equal to 2 + 32 is 34 plus 64 is 98 So one mold has been sulfurized is equivalent to 98 grams of sulfuric acid so far we know two things in a mole there are 6.022 times 10 to the 23 particles whether they are atoms or molecules and in a mole there is the same mass of the atom or the molecule but expressed in grams now let's do calculations converting from moles to grams from moles to atoms and vice versa my the following examples then let's suppose we have these two exercises we are going to convert 0.57 moles of aluminum into grams and 4.3 grams of manganese into moles here it tells us that to convert from moles to grams we are going to multiply by the molar mass in this case it will be the atomic mass of aluminum which is 26.9 and we are going to round it up to have only two significant figures so we are going to say that it is 27 rounded up so we are going to simply multiply by 27 This is going to be equal like this 057 times 27 equals we are going to do it on a calculator 0.57 is multiplied by 27 equals 15.39 15.39 grams of aluminum that easy 0.57 moles of aluminum is equivalent to 15.39 grams of aluminum and 4.3 grams of manganese we simply have to divide them by the molar mass between the molar mass of manganese manganese has a molar mass or an atomic mass of 54.93 But we can round it up to 55 so as not to complicate things, so we say that 4.3 divided by 55 is equal to the following: 4.3 by 55 is equal to 0.078 0 0 78 moles of manganese something to notice here is that when we say moles and we do not put an e s because the symbol for mole is mol and symbols do not have plurals. So you say moles by writing only the word mole. Let's look at other examples. We have five moles of sulfuric acid, let's convert them to grams. Another way to do it is by doing the same procedure but better said, better written, is by placing that 5 moles of sulfuric acid are multiplied by a factor that we call a molar factor. A molar factor is a fraction or a ratio that contains the equivalence of one mole of the substance in grams, so we place here below mole of sulfuric acid and above we place grams of theoretical acid, if you notice, we have here moles that are multiplying or as a numerator and moles also that are as a denominator and therefore they cancel out and simply above we put the equivalence of a mole of sulfuric acid which is 98 grams of sulfuric acid as we saw previously remember that to know this number we multiply the mass of hydrogen by two plus the mass of sulfur plus the mass of oxygen by 4 the mass of hydrogen by 2 gives us 2 plus the mass of sulfur gives us 32 plus the mass of oxygen which is 16 by 4 gives us 64 and this gives us 98 from there this 98 comes out then we simply now go to do the respective multiplication 5 by 98 we do it here if you want in a calculator 5 by 98 is equal to 490 will be grams of sulfuric acid and that's it and now how about they say that we have 342 grams of carbon dioxide and that we have to convert them into moles So first we have to get the molar mass of carbon dioxide remember that the molar mass of carbon dioxide is obtained by adding the mass of carbon which is 12 + the mass of oxygen which is 16 by 2 the mass of carbon is 12 plus the mass of oxygen is 16 times 2 or 32 this total gives us 44 then we are going to multiply by that molar factor we say that the grams of carbon dioxide as they are here in the numerator go here also in the denominator so that they can be cancelled and as we are going to convert to moles we place moles of CO2 above as we know that in a CO2 mold there are 44 grams of CO2 we do the operation first canceling the grams of CO2 with the grams of CO2 and we have a division 342 between 44 so 342 between 44 is equal to 7.77 and the answer is 7.77 moles of CO2 now we are going to convert from moles to atoms and from atoms to moles or also from moles to molecules and from molecules to moles now to convert from moles to particles remember that particles can be atoms or molecules we simply multiply by Avogadro's number and to convert from particles to moles we divide by Avogadro's number let's look at several exercises so you can see how apply this for example we have 4.8 moles of calcium to convert them into calcium atoms we simply have to multiply by Avogadro's number or 6.022 times 10 to the 23 we do that in the calculator as follows 4.8 times 6.022 and we are going to use the exponential key that here in my calculator is a little erased saying exponential already with that with only the e we already have by 10 and we simply place 23 we have to place exponential by 1-0 no Simply exponential 23 and we give it the same that tells us that there are 2.89 times 10 to the 24 we must not forget the little number that appears here 10 to the 24 so that we take it into account let's see if it is seen here more or less you can see then there it is 2.8 or 2.9 rounded by 10 to the 24 this is equal to 2.9 times 10 to the 24 and since we are talking about calcium they are atoms I'll put in atoms like at of calcium and we already have the answer there now how about we convert 2.35 times 10 to the 24 atoms of copper to convert from atoms to moles we simply have to divide by the lawyer number So we're going to do this like this 2.35 times 10 to the 24 divided by 6.022 times 10 to the 23 let's do it quickly on a calculator like this 2.35 exponential 24 divided by 6.022 exponential 23 equals 3.9 moles of copper 3.9 moles of copper is the answer and there So we have How to convert from moles to particles and from particles to moles this applies can be with atoms like copper or like sulfur or like hydrogen it can also be applied with molecules like carbon dioxide water sulfuric acid and other molecules let's just apply this and we're not going to have any problems Now what happens if it tells us to convert from grams atoms it can be simple we just do what we did from grams to moles and then convert from moles to atoms simple how do we do it let's suppose we have 24 grams of Magnesium and we are going to convert them to atoms So magnesium we already said that it weighs 24.3 grams So we are going to say that to convert to moles we simply divide by the molar mass That is we write the mass here 24.3 grams of Magnesium are in a mole of Magnesium and then to convert from moles to atoms Because here we are going to cancel grams of Magnesium with grams of Magnesium from moles to atoms we simply have to multiply by Avogadro's number which we already know that in a mole of magnesium there is Avogadro's number or 6.022 by 10 to the 23 atoms of Magnesium So we are going to have moles of Magnesium and moles of Magnesium canceled simplified What operation are we going to do we are going to do 24 by 1 which gives us the same by 6.022 by 10 to the 23 and we divide it by 24.3 by 1 that we are going to ignore the numbers 1 so that the operation does not get tangled up and in the calculator it would be as follows 24 by Avogadro's number which is 6.022 exponential 23 between 24.3 this is equal to 5.94 times 10 to the 23 5.94 which can also be rounded to 95 5.95 times 10 to the 23 atoms of Magnesium and there we arrive So at the end of this video we can do the same if they ask us for atoms to grams we do the opposite we go from atoms to moles and from moles to grams if you liked this video please subscribe to the Channel and if you want to tell us something about the video if you thought it was excellent or you thought it was very bad leave me a comment please share this video if it was useful to you I am Yamil Córdoba Join the Channel to support our growth and see you next time bye [Music]