50% can be entered as .50 or 50%.) 4.5: Empirical and Molecular Formulas - Chemistry LibreTexts So, for example, you could be referring to a molecule of benzene. Fe can be Fe+3 or Fe+5), so in this case the oxidation number/charge of the mercury needs to be specified. By using our site, you agree to our. From this information, we can calculate the empirical formula of the original compound. Ans: Mass of aluminium \( = 1.08\,{\text{g}}\) Mass of oxygen \(0.96\,{\text{g}}\) Number of moles \( = {\text{mass}}/{\text{atomic}}\,{\text{mass}}\) No. The molecular formula represents the total number of elements present whereas the empirical formula represents the smallest ratio between the individual atoms. Direct link to Cole B's post Oxygen-16 use to be the b, Posted 6 years ago. Finding the empirical and molecular formula is basically the reverse process used to calculate mass percent or mass percentage . why do we use empirical formula ? Empirical Formula Calculator - ChemicalAid And we see that that's actually integer multiples of the subscripts of the empirical formula). Molecular Formula = n ( Empirical formula) therefore n = Molecular Formula Empirical Formula The calculation depends on the information provided. Mass of Mg = 0.297 g. Mass of magnesium oxide = mass of Mg + mass of O. An empirical formula can be calculated through chemical stoichiometry. Thanks. m/n = M with n = numer of moles; m = mass in grams (g); and M = molecular mass of the compound in grams/moles. It is determined using data from experiments and therefore empirical. Direct link to Greg L's post Why do we assume that the, Posted 8 years ago. Empirical Formula Calculator - ezcalc.me 3.5: Empirical Formulas from Analysis - Chemistry LibreTexts Why can't the percents be saying that we have a mole ratio just over 3:1? Much of the information regarding the composition of compounds came from the elemental analysis of inorganic materials. I.e. Thanks to all authors for creating a page that has been read 69,883 times. Any compounds chemical formula can be defined using one of two types of formulas: molecular formulas and empirical formulas. Could anybody please explain? 2 / 1.5 = 1.33. An empirical formula represents the simplest whole-number ratio of various atoms present in a compound. Therefore, your atomic ratio of whole numbers is. conventions that do give more information, but you might say, well, I actually want to know more about the actual particular Try 2. know, I from empirical evidence I now believe this, this the grams will cancel out and we're just going to be left with a certain number of moles. This is how many moles When I paused the video, I didn't look at moles, but just used the fraction of the weight divided by the atomic mass to get the relative amount of each, which came out to close to the same answer (a 2.1 to 1 ratio of Cl to Hg). 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Thus, H2O is composed of two atoms of hydrogen and 1 atom of oxygen. Next, divide each elements gram atoms by the smallest weight to find the atomic ratio, then convert it to whole numbers. Benzene, for example, has the molecular formula \({{\text{C}}_6}{{\text{H}}_6}.\) This means that one molecule of benzene is made up of six carbon atoms and six hydrogen atoms. Worked example: Determining an empirical formula from percent Percentages can be entered as decimals or percentages (i.e. To determine the molecular formula, enter the appropriate value for the molar mass. Sign up for wikiHow's weekly email newsletter. Direct link to daisyanam2's post So there are 2 Cl for eve, Posted 9 years ago. This means a 100-gram sample contains: What if the weight of the unknown compound is 500 g/mol? Direct link to RogerP's post Here is an example. https://chemed.chem.purdue.edu/genchem/probsolv/stoichiometry/empirical2/ef2.4.html, https://chem.libretexts.org/Courses/University_of_Arkansas_Little_Rock/Chem_1402%3A_General_Chemistry_1_(Kattoum)/Text/2%3A_Atoms%2C_Molecules%2C_and_Ions/5.13%3A_Percent_Composition, http://www.thefreedictionary.com/gram+atom, https://sciencing.com/calculate-theoretical-percent-2826.html, https://www.bbc.com/bitesize/guides/z8d2bk7/revision/4, https://www.cohassetk12.org/cms/lib010/MA01907530/Centricity/Domain/345/Adv%20Chem/Unit%206%20Emp%20form%20and%20Stoich/6.2%20EMPIRICAL%20FORMULA.pdf, http://www.softschools.com/formulas/chemistry/percent_composition_formula/130/, https://sciencing.com/calculate-mass-ratio-8326233.html, https://sccollege.edu/Departments/STEM/Questions/Wiki%20Pages/Empirical%20Formula.aspx, https://www.khanacademy.org/science/chemistry/chemical-reactions-stoichiome/empirical-molecular-formula/v/empirical-molecular-and-structural-formulas, https://sciencing.com/spectrometer-experiments-8080239.html, calculer la formule empirique d'un compos chimique, A compound that is made up of 40.92% Carbon, 4.58% hydrogen, and 54.5% Oxygen would have an empirical formula of C. In a chemistry lab, to find the percentage composition, the compound would be examined through some physical experiments and then quantitative analysis. 6.8: Calculating Empirical Formulas for Compounds The empirical rule can also determine how standard a set of data is. So hopefully this at least begins to appreciate different ways of referring to or representing a molecule. Empirical Formula & Molecular Formula Determination From - YouTube Good question. approximate how many moles because the grams are going to cancel out, and it makes sense that (It seems like C tends to be written first?). That may not satisfy you, you might say, well, OK, but how are these six carbons and six hydrogens actually structured? The molecular formula shows the exact number of different types of atoms present in a molecule of a compound. Molecular and empirical formulas (video) | Khan Academy Direct link to RACHEET's post We are taught in our scho, Posted a month ago. means that you saw data. variant of a structural, it's hard to see this one I just drew, so let me see if I can do a little bit Oh, that's about as good, Multiply , Posted 9 years ago. The simplest formula utilises these whole numbers as subscripts.Empirical Formula \( = {{\text{R}}^*}\) whole number. But just the word "benzene" This is multiplied by 100 percent and divided by the compound's molar mass. weren't able to look at just one molecule, but Direct link to Zhanna Berridge's post Why hydrargyrum"s name is, Posted 8 years ago. The relative amounts of elements could be determined, but so many of these materials had carbon, hydrogen, oxygen, and possibly nitrogen in simple ratios. The ratios hold true on the molar level as well. Thus, H 2 O is composed of two atoms of hydrogen and 1 atom of oxygen. Well, that might be, in that case, it might be useful to move To create this article, volunteer authors worked to edit and improve it over time. Read on! If I have one mole for chlorine, on average on earth the average You essentially are losing information. Note that CaCO3 is an ionic compound. aren't always different if the ratios are actually, also show the actual number of each of those elements that you have in a molecule. Lesson 3: Elemental composition of pure substances. Likewise, 1.0 mole of H2O is composed of 2.0 moles of hydrogen and 1.0 mole of oxygen. We see that one mole of mercury Moles are just the quantity 6.8: Calculating Empirical Formulas for Compounds is shared under a CK-12 license and was authored, remixed, and/or curated by Marisa Alviar-Agnew & Henry Agnew. And the molecular formula each of these do you actually have in a benzene molecule? C=40%, H=6.67%, O=53.3%) of the compound. Mercury forms a compound with chlorine that is 73.9% mercury and 26.1% chlorine by mass. Solution: Step 1: To create this article, volunteer authors worked to edit and improve it over time. Assume a \(100 \: \text{g}\) sample of the compound so that the given percentages can be directly converted into grams. https://chem.libretexts.org/Courses/Eastern_Wyoming_College/EWC%3A_Introductory_Chemistry_(Budhi)/06%3A_Chemical_Composition/6.8%3A_Calculating_Empirical_Formulas_for_Compounds, https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Map%3A_Introductory_Chemistry_(Tro)/06%3A_Chemical_Composition/6.08%3A_Calculating_Empirical_Formulas_for_Compounds, https://openstax.org/books/chemistry-2e/pages/3-2-determining-empirical-and-molecular-formulas, https://sccollege.edu/Departments/STEM/Questions/Wiki%20Pages/Empirical%20Formula.aspx, https://www.chemteam.info/Mole/Emp-formula-given-percent-comp.html, http://chemcollective.org/activities/tutorials/stoich/ef_molecular, https://pressbooks.bccampus.ca/chem1114langaracollege/chapter/3-2-determining-empirical-and-molecular-formulas/, These are the instructions you should follow if the above is true. the likely empirical formula. Direct link to Shahzaib R.'s post I know this maybe a dumb , Posted 6 years ago. for every two hydrogens, for every two hydrogens, and since I already decided to use So water we all know, The mass of each component in one mole of the substance is first calculated using the formula. The LibreTexts libraries arePowered by NICE CXone Expertand are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. table of elements is useful. It is the formula of a compound expressed with the smallest integer subscript. To log in and use all the features of Khan Academy, please enable JavaScript in your browser. There are 7 references cited in this article, which can be found at the bottom of the page. How to calculate empirical formula - Easy to Calculate - What I want to do in Use each element's molar mass to convert the grams of each element to moles. Empirical formulas show the simplest whole-number ratio of atoms in a compound, molecular formulas show the number of each type of atomin a molecule, and structural formulas show how the atoms in a molecule are bonded to each other. The simplest formula of a compound is directly related to its per cent composition. Empirical, molecular, and structural formulas Molecular and empirical formulas Worked example: Determining an empirical formula from percent composition data Worked example: Determining an empirical formula from combustion data Elemental composition of pure substances Science > Class 11 Chemistry (India) > Some basic concepts of chemistry > or comes through experiments. That's why that periodic Direct link to Petrus's post Around 2:40, Sal says tha, Posted 7 years ago. show us that the ratio for every carbon we have a hydrogen. what would the ratio look like if you were given a formula of 3 different elements? you have an oxygen. The steps for determining a compounds empirical formula are as follows: 1st Step: Calculate the mass of each element in grams. To calculate the percent composition, the masses of C, H, and O in a known mass of C 9 H 8 O 4 are needed. 0.36, and I'll just say 0.36 because this is going to be a little bit of an estimation game, Let's just assume it is, or this entire container is 100 grams. Q.1. 3.4: Determing an Empirical and Molecular Formula Likewise, 1.0 mole of H2O is composed of 2.0 moles of hydrogen and 1.0 mole of oxygen. Its molar mass is \(98.96\,{\text{g}}.\) What are its empirical formula and molecular formula?Ans: Step 1) Convert the percentage to grams. type of empirical analysis, you're not going to get exact results, and it's best to assume the simplest ratio that gets you pretty close. So when we multiply this out, On the other hand, if the subscripts do not all share a common factor, the molecular formula is also the empirical formula. You have an oxygen. Chapter # 1 || example 3 & 4 || exercise Q.No. 16 and 17 - YouTube These are not whole numbers so 2 doesnt work. The compound has the empirical formula CH2O. Frequently asked questions related to the simplest formula are listed as follows: Q.1: Define the molecular formula.A: The molecular formula represents the total number of different atoms present in one molecule of the given compound. If we know which elements are present in a molecule and in what ratio, we can calculate the molecule's empirical formula. Thus, H 2 O is composed of two atoms of hydrogen and 1 atom of oxygen. And this is only one Well, it looks like for References. A compound was discovered to contain \(32.65\% \) sulphur, \(65.32\% \) oxygen, and \(2.04\% \) hydrogen. a hydrogen right over there. I'll even say roughly right over there, and I can do the same thing with chlorine. Empirical formulae - Chemistry calculations - BBC Bitesize Since the moles of \(\ce{O}\) is still not a whole number, both moles can be multiplied by 2, while rounding to a whole number. The chemical formula CaOCl2 refers to one calcium atom, one oxygen atom, and two chlorine atoms. Leading AI Powered Learning Solution Provider, Fixing Students Behaviour With Data Analytics, Leveraging Intelligence To Deliver Results, Exciting AI Platform, Personalizing Education, Disruptor Award For Maximum Business Impact, Copyright 2023, Embibe. I could have assumed If you want to see the structural formula, you're probably familiar with it or you might be familiar with it. , an unknown compound can be analyzed in the laboratory in order to determine the percentages of each element contained within it. To create this article, volunteer authors worked to edit and improve it over time. Divide the subscript of 8 by the GCF of 8: 8 / 8 = 1, Divide the subscript of 16 by the GCF of 8: 16 / 8 = 2. there is a video on this topic which explains it in detail, i would suggest you to gradually get there. as I go from empirical to molecular to structural formula. 6.7: Mass Percent Composition from a Chemical Formula, 6.9: Calculating Molecular Formulas for Compounds, Identify the "given" information and what the problem is asking you to "find.". If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. c. Divide both moles by the smallest of the results. Molecular formula. 40.92% of the vitamin C is made up of carbon, while the rest is made up of 4.58% hydrogen and 54.5% oxygen. Each of those oxygens in a water molecule are bonded to two hydrogens, are bonded to two hydrogens. How do you depict Benzoic acid as a molecular and empirical formula? the moles we have of chlorine and then that will inform Direct link to Prashanth Jeyabaskaran's post Hydrargyrum is the Latin , Posted 9 years ago. wikiHow is a wiki, similar to Wikipedia, which means that many of our articles are co-written by multiple authors. And so this is going to All tip submissions are carefully reviewed before being published. What does the 2 mean? Enter an optional molar mass to find the molecular formula. Structural formula, which will actually Multiply each of the moles by the smallest whole number that will convert each into a whole number. 27 grams is less than 35.45. The empirical formula is distinct from the molecular formula in that it represents the simplest ratio of atoms involved in the compound. Direct link to dhriti.bhowmick's post I could not exactly under, Posted a year ago. OK, first some corrections. By using our site, you agree to our. The name of this molecule happens to be mercury two chloride, Method 1 Understanding the Basics 1 Know what the empirical formula is. Unless you are in a lab, you will not need to actually do these experiments. Last Updated: December 22, 2022 Well, if it's not drawn, The empirical formula of a chemical compound is the simplest whole number ratio of atoms present in the compound. Let me do water. and I won't go in depth why it's called mercury two chloride, but that's actually what we the case in one molecule, for every six carbons As a small thank you, wed like to offer you a $30 gift card (valid at GoNift.com). And for that, you would wanna go to a structural formula. There are two kinds of percents here: the mass fraction and the mole fraction. Thus C, H and O are in the ratio of 1:2:1 . how to find the molecular formula like when calcium carbonate is equal to caco3. What is the compounds simplest formula?Ans: Step 1) Convert the percentage to grams. And you might be thinking, what does empirical mean? This article has been viewed 69,883 times. So an empirical formula gives you a ratio of the elements in the molecule. Posted 9 years ago. So if we assume 100 grams, That was 73% by mass (not .73%) Hg and 27% by mass (not .27%) Cl. how many moles this is by looking at the average We can also work backwards from molar ratios because if we know the molar amounts of each element in a compound, we can determine the empirical formula. 10.13: Determining Molecular Formulas - Chemistry LibreTexts For example, if your empirical formula contains 29.3 percent sodium, convert it to 29.3 grams. Q.4: Why do we use the empirical formula?A: Empirical formulas are the most basic notational form. Its empirical formula is CH2O. Why hydrargyrum"s name is mercury in this video? Empirical Rule Calculator The first step in determining the molecular formula of a compound is to calculate the empirical mass from its empirical formula. Empirical, empirical. But if you are still confused, and you like to reason by analogy, think of it this way. Why is Cl called Chloride? atomic mass is 35.45 grams. If you count all the elements' molecular weights together (multiplied by how often the compound contains it), the result should be 500 g/mol. Is it C5H4N2O or..? {\text{F=2}} \times {\text{C}}{{\text{H}}_2}{\text{Cl}} = {{\text{C}}_2}{{\text{H}}_4}{\text{C}}{{\text{l}}_2}.\). In this article, we will study in detail the empirical formula and how to calculate it. of mercury, that's a number. at each of these vertices, and then you say, OK, carbon's gotta have, not gotta, but it's So one, going to write this way, one, two, three, four, five, six carbons in a hexagon just like that. this video is think about the different ways to So if we assume a ratio Empirical, molecular, and structural formulas - Khan Academy It just so happens to be, 2.5 / 1.5 = 1.66. To create this article, volunteer authors worked to edit and improve it over time. Direct link to sharan's post how do you actually calcu, Posted 8 years ago. Research source. Lets say that the assignment asks you to look at a sample of vitamin C. It lists 40.92% Carbon, 4.58% hydrogen 54.5% Oxygenthis is the percent composition. Now, I want to make clear, that empirical formulas and molecular formulas Empirical Formulas. Empirical formula. that's when you would want to go to the molecular formula. The empirical formula is the simplest formula for a compound, defined as the ratio of subscripts of the formula's smallest conceivable an entire number of parts. It is sometimes referred to as the simplest formula. other and what keeps the hydrogens kind of tied to each, or, the hydrogens tied to the This division yields. Direct link to Quinn McLeish's post Because atoms tend to dif, Posted 8 years ago. And there's other naming A double bond is where there are four electrons shared between two atoms. Find the empirical formula of the compound. The easiest definition of empirical formula is that it is the simplest ratio of the number of atoms involved in the compounds formation. This is one variant of So there's multiple ways So pause this video and Multiply them both by 2 so you get a ratio of 2:3. likely empirical formula. up to the empirical formula. \({\text{S=1}}\) \({\text{O=4}}\) \({\text{H=2}}\) Therefore, the empirical formula will become \({{\text{H}}_2}{\text{S}}{{\text{O}}_4}.\), Calculation of Molecular Formulas from the Simplest Formula, Q.3. And the 2 denotes the charge of the cation, because transition metals have multiple oxidation states (which is essentially the charge of the atom within the molecule) (i.e. Thanks to all authors for creating a page that has been read 64,560 times. I know this maybe a dumb question but what are double bonds? Next, divide all the mole numbers by the smallest among them, which is 3.33. Our whole number ratio is therefore Carbon(C): Hydrogen(H): Oxygen(O) =. because early chemists, they can't look, they Each of these lines that I'm drawing, this is a bond, it's a covalent bond, we go into much more depth For. \(32.65{\mkern 1mu} {\rm{g}}/32\,{\mkern 1mu} {\rm{g}}\,{\mkern 1mu} {\rm{mo}}{{\rm{l}}^{ 1}} = 1.0203{\mkern 1mu} \,{\rm{moles}}{\mkern 1mu} \,{\rm{S}}\) \(65.3{\mkern 1mu} {\rm{g}}/16{\mkern 1mu} \,{\rm{g}}{\mkern 1mu} \,{\rm{mo}}{{\rm{l}}^{ 1}} = 4.08{\mkern 1mu} \,{\rm{moles}}\,{\mkern 1mu} {\rm{O}}\) \(2.04{\mkern 1mu} {\rm{g}}/1.008{\mkern 1mu} \,{\rm{g}}{\mkern 1mu} \,{\rm{mo}}{{\rm{l}}^{ 1}} = 2.024{\mkern 1mu} \,{\rm{moles}}{\mkern 1mu} \,{\rm{H}}\) Step 3) Next, take the smallest Answer in moles from the previous step and divide all of the others by it. \(4.07\,{\text{g}}\) of \({\rm{H}}/1{\mkern 1mu} \,{\rm{g}}{\mkern 1mu} \,{\rm{mo}}{{\rm{l}}^{ 1}} = 4.07{\mkern 1mu} \,{\rm{moles}}\) \(24.27\,{\text{g}}\) of \({\rm{C}}/1{\mkern 1mu} 2{\mkern 1mu} \,{\rm{g}}{\mkern 1mu} \,{\rm{mo}}{{\rm{l}}^{ 1}} = 2.02{\mkern 1mu} \,{\rm{moles}}\) \(71.65\,{\text{g}}\) of \({\rm{Cl}}/35.5{\mkern 1mu} \,{\rm{g}}{\mkern 1mu} \,{\rm{mo}}{{\rm{l}}^{ 1}} = 2.02{\mkern 1mu} \,{\rm{moles}}\) Step 3) Next, take the smallest answer in moles from the previous step and divide all of the others by it, \(4.07\) moles of \({\text{H}}/2.02 = 2\) \(2.02\) moles of \({\text{C}}/2.02 = 1\) \(2.02\) moles of \({\text{Cl}}/2.02 = 1\) Step 4) Finally, the coefficients calculated in the previous step will become the chemical formulas subscripts. The simplest formula represents the percentage of elements in a compound. Finding empirical formula from given moles - YouTube \({\text{H}} = 2\) \({\text{C}} = 2\) \({\text{Cl}} = 1\) Therefore, the empirical formula of the compound will be \({\text{C}}{{\text{H}}_2}{\text{Cl}}{\text{. To calculate the empirical formula, enter the composition (e.g. one right over here. Use it to try out great new products and services nationwide without paying full pricewine, food delivery, clothing and more. Empirical formula and molecular formula - Quantitative chemistry Still, there is another way of representing compounds by their simple whole-number ratio of different types of atoms present in one compound molecule. 3.2 Determining Empirical and Molecular Formulas - OpenStax The ratios hold true on the molar level as well. Also note that the atomic weights used in this calculation should include at least four significant figures. I only see one, two, three. As ionic compounds generally occur in crystals that vary in number of groups of empirical units, the molecular formula is the empirical formula. The subscripts are whole numbers and represent the mole ratio of the elements in the compound. Direct link to Luke's post Note that CaCO3 is an ion, Posted 6 years ago. Use it to try out great new products and services nationwide without paying full pricewine, food delivery, clothing and more. Next, convert the grams to moles by dividing 29.3 grams by the atomic weight of sodium, which is 22.99 grams, to get 1.274. References. typically going to have four bonds in its stable state, will actually give you some 3D information, will The chemical formula will always be some integer multiple ( n) of the empirical formula (i.e. wikiHow is where trusted research and expert knowledge come together. Direct link to Matt B's post Yes, entirely correct. If you have any doubts related to the article, please reach out to us through the comments section, and we will get back to you as soon as possible. Multiply each of the moles by the smallest whole number that will convert each into a whole number. Glucose has the molecular formula C6H12O6. For example, lets say that we have a compound that is made up of 40.92% carbon. If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. the ratios of the different elements that they had in a molecule. In contrast to molecular formulae, they will not know the total number of atoms in a single molecule. C2H6 (Ethane) has a ratio of 2 to 6. simplified, double bonds occur when atoms share 4 electrons (in single bonds they share 2). So the most obvious way is its name. is 200.59 grams on average, so we could multiply this times one over 200.59 moles per gram. If you're seeing this message, it means we're having trouble loading external resources on our website. terms of empirical formula, in terms of ratios, but see if you can come up with what is likely the empirical formula for our mystery molecule in here, and as a little bit of a hint, a periodic table of Empirical. elements might be useful. This means that you have It is the formula of a compound expressed with the smallest integer subscript. For example, if a compound is 40.92 percent carbon, multiply 40.92 by 12, its atomic mass, to get 3.4. \({\rm{m/atomic mass}}\,{\rm{ = }}\,{\rm{molar quantity }}\left( {\rm{M}} \right)\)3rd Step: Divide the number of moles of each element from the smallest number of moles found in the previous step.\({\rm{Atomic Ratio}}\,{\rm{ = }}\,{\rm{M/least M value }}\left( {\rm{R}} \right)\)4th Step: Converting numbers to whole numbers is as simple as multiplying one by the smallest number, which yields only whole numbers. 29.3 g Na * (1 mol S / 22.99 g Na) = 1.274 mol Na, 41.1 g S * (1 mol S / 32.06 g S) = 1.282 mol S, 29.6 g O * (1 mol O / 16.00 g O) = 1.850 mol O. every one mercury atom, there is roughly two chlorine atoms.