For information on South Africa's response to COVID-19 please visit the COVID-19 Corona Virus South African Resource Portal. -Ocimene is a pleasant-smelling hydrocarbon found in the leaves of certain herbs. What is the simplest empirical formula for the compound. It is burned completely under tightly controlled laboratory conditions (i.e. Unsaturated hydrocarbons are hydrocarbons that have double or triple covalent bonds between adjacent carbon atoms.The term "unsaturated" means more hydrogen atoms may be added to the hydrocarbon to make it saturated (i.e. If its molecular mass is 5 8 g r a m. m o l e 1, determine the molecular formula of the hydrocarbon. In combustion analysis, an organic compound containing some combination of the elements C, H, N, and S is combusted, and the masses of the combustion products are recorded. Then using the molality formula, molality = moles of solute/kg of solvent Rearrange and solve for the moles of solute using the grams of lauric acid (make sure you convert from grams to kg). Molecular ion measurements in a mass spectrometer show that the hydrocarbon has a molecular mass of 44 - from the molecular ion peak. Your project is to determine the molecular formula of an unknown hydrocarbon (a compound consisting of only carbon and hydrogen). all products are recoverable, there are no side reactions, etc. Caffeine has the following composition: 49.48% of carbon, 5.19% of hydrogen, 16.48% of oxygen and 28.85% of nitrogen. M+ at m/z = 84 implies an even # of nitrogen M+ peak it is not the base peak, recalculation necessary The compound has the empirical formula CH2O. To find the actual molecular formula, divide 240, the molar mass of the compound, by 79.10 to obtain 3. Your molecular formula may allow you to differentiate. What is its molecular formula? Determine the molecular formula. An unknown, foul-smelling hydrocarbon gives the mass spectrum and infrared spectrum shown. Assuming the Hydrocarbon has no other atoms such as Oxygen or Nitrogen etc. Dividing the gram molecular mass by this value yields the following: Assume 100 g of compound. and. Indoxyl sulfate is also a metabolite of tryptophan derived from dietary protein. (b) Use the IR spectrum to determine the functional group (s), if any. (i) Using the formula DT = Kf x molality to determine the molality. An unknown hydrocarbon has a molecular ion peak at m/z = 84, with a relative intensity of 31.3. Molar mass of carbon is 12 g / m o l and that of hydrogen is 1 g / m o l. Hence there are 43 g 12 g / m o l = 3.58 m o l 3.6 m o l of carbon for every 7.2 g 1 g / m o l = 7.2 m o l of hydrogen. In combustion analysis, an organic compound containing some combination of the elements C, H, N, and S is combusted, and the masses of the combustion products are recorded. If we have 20 moles of the hydrocarbon above, how many moles of water will be produced assuming the reaction goes to completion? Incomplete Combustion of Hydrocarbons. The latter amount is most convenient and would simply involve the use of molar masses instead of atomic and formula masses, as demonstrated Example 3.10.As long as the molecular or empirical formula of the compound in question is known, the percent Add this number back into the chemical formula (CnH2n+1) and append the halogen for the complete chemical formula. Download Acetylene, ethyne, ball-and-stick model, molecular and chemical formula. Popular Answers (1) Identifing an completely unknown only by MS is difficult, even if you have high res and MS/MS data.If you have a high resolution mass spectromter it (Assume that the hydrocarbons are noncyclical and there is no more than one multiple bond.) What is the molecular formula of this substance? Unfortunately, your shopping bag is empty. x = 1 and (x + y/4) = 2. 4. Divide the gram molecular mass by the empirical formula mass. Solution. 2. Convert 10 lbs to grams, divide by the molecular weight of sugar, multiply by avogadro's number, multiply by 12. there is the answer. How many elements of unsaturation are there? Exploiting the uniqueness of the soloMERTM technology for the development of next-generation, super-potent drug modalities for chronic autoimmune inflammation diseases, and beyond - Double & triple bonds are assigned the lowest possible number. 0.466 mol H x 1g H/1 mol H = 0.466 g H. 0.233 mol C x 12g C/1 mol C = 2.80 g H. 0.466g H + 2.80g C = 3.27g. The observations were recorded in a table. Example 3: Spiro[2.2]pentane. So the formula is three times the empirical formula, or C 15 H 15 N 3. We should have oxygen as a limiting reagent and hydrocarbons as an excess reagent. Olefinic hydrocarbons (olefins): Unsaturated hydrocarbon compounds with the general formula CnH2n containing at least one carbon-to-carbon double-bond. A saturated molecule contains only single bonds and no rings. 13 What is the empirical formula of benzene? Example: 14.42 g / 0.0377 mol = 382.49 g/mol. Then divide the grams of gas by the moles of gas present to yield molecular weight. For example-The molecular formula of Butane is \({{\rm{C}}_4}{{\rm{H}}_{10}}\) and is the smallest hydrocarbon alkane that has isomers. ular formula, Mu=the molecular weight of the unknown mixture. Suggested Solution: Using the general equation and applying volume ratio, we have. This same approach may be taken considering a pair of molecules, a dozen molecules, or a mole of molecules, etc. In a hydrocarbon, the percentage of carbon and hydrogen are 8 5. A 0.30g of an unknown organic compound X gave 0.733g of carbon dioxide and 0.30g of water in a combustion analysis.Determine the empirical formula. A hydrocarbon is a compound comprised of carbon and hydrogen atoms. An unknown hydrocarbon is found to contain 85.7% carbon and an atomic mass of 84.0 g/mol. What is its molecular formula? When treated with rhodium during catalytic Example #3: A 0.2500 g sample of a compound known to contain carbon, hydrogen and oxygen undergoes complete combustion to produce 0.3664 g of CO 2 and 0.1500 g of H 2 O. This chemistry video tutorial explains how to find the empirical formula and molecular formula using combustion analysis. and Suggested Solution: Using the general equation and applying volume ratio, we have CxHy (g) + (x + y/4) O2 (g) > xCO2 (g) + y/2 H2O (l) 10cm3 20cm3 .10cm3 1mol 2 mol 1 mol Based on the above comparision, we have x = 1 and (x + y/4) = 2 Solving it gives y = 4 A hydrocarbon is a compound comprised of carbon and hydrogen atoms. The empirical formula is C 5 H 5 N, which has a molar mass of 79.10 g/mol. Used as fuel, for welding, cutting and for carbide lamps and as chemical building block. A doublet is characteristic of a primary amine or and amide derived from ammonia. The kidneys are responsible for 85% of total furosemide total clearance, where about 43% of the drug undergoes renal excretion. determine the mass in grams by treating the percentage values as masses (by mass composition) calculate the mole of each element by mass/molar mass. C2H2, hydrocarbon and simplest alkyne. If you unknown contains broad absorption from 3600-3000, your molecule could have an O-H or N-H stretch. The configuration of an unsaturated carbons include straight chain, such as alkenes and alkynes, as well as branched C1H1. 85.7/12 : 14.3/1 6. 3.The Moody friction factor is impacted by the characteristic of the flow in the pipe. 11 What is the empirical formula of H2O? The Moody friction factor, f, expressed in the previous equations, is a function of the Reynolds number and the roughness of the internal surface of the pipe and is given by Fig. An unknown hydrocarbon has a molecular ion peak at m/e = 84, with a relative intensity of 31.3. On hydrogenation with a palladium catalyst, 2, 6-dimethyloctane is obtained. An unknown hydrocarbon is found to contain 85.7% carbon and an atomic mass of 84.0 g/mol. Example 1. Check the multiplicity of this peak. Solved Examples. Find its empirical formula. When treated with rhodium during catalytic Combustion analysis is used to determine the empirical formula of hydrocarbons (a compound containing only hydrogen and carbon). The paraffin is burned with air, and there is no CO in the combustion products. Transcribed image text: It's on Fire Your project is to determine the molecular formula of an unknown hydrocarbon (a compound consisting only of hydrogen and carbon). C O X 2 C 44 g 12 g 3.30 g x. x = 0.9 g, moles of C = 0.9 12 = 0.075. ( 2 c + 2 + N x H) 2. 12 How is an empirical formula like a molecular formula? Consequently, a full combustion analysis problem might look like this: Problem #1: A 1.50 g sample of hydrocarbon undergoes complete combustion to produce 4.40 g of CO 2 and 2.70 g of H 2 O. If the freezing point of "pure" G, tl, is not too much below the freez ing point of G for zero impurity, ilo' then the molecular weight of the unknown is obtained with sufficient accuracy from the following equations: -In N'=A(t/-t! 1 pound is = 453.59 g 453.59 g * 10 pounds http://Leah4sci.com/NMR presents: Proton NMR Practice on Predicting Molecular Structure Using Formula + GraphNeed help with Orgo? ), and the only available source of oxygen is a balloon inflated with pure oxygen gas and attached Carbon : Hydrogen 5. Answer (1 of 5): This is worked out by the ratios of the carbon to the hydrogen. Please answer the following: 1) Calculate the molecular. Home; Services; Gallery; Scientific Publication; Testimonials; News; Online Payment hydrocarbon H in an unknown mixture of hydrocarbons can be de termined by measurement of the lowering of the freezing point of a sample of pure H caused by the addition to it of a given amount of the unknown mixture. The M+1 peak has a relative intensity of 2.06, and the M+2 peak has a relative intensity of 0.08. Several of the problems below include this question and you can go here for a discussion about calculating the molecular formula once you know the empirical formula. Answer (1 of 11): Empirical formula = molecular mass = CH2 Molar mass = 84 g/mol Empirical mass for CH2 = (12 + 2) = 14 Now how many molecules fit into the molar mass of 84? Rule 3: Name each substituent. Answer (1 of 4): There is no such thing as a relative molecular formula, or at least I should say that in 45 years of being a professional chemical engineer, I have never heard that term used. This video shows how to get the formulas for alkanes,m alkenes and alkynes using the general formulas. In this video we want to discuss how to use the combination analysis to determine the molecular fan of a gas hydrocarbon cxhy.The unknown balanced equation of the hydrocarbon combuence in excess oxygency to obtain carbon and water is the following: It should be noted that all carbon in which hydrocarbon is converted into carbon dioxide CO2, Empirical formula and molecular formula calculation Example 8.6 for a hydrocarbon compound On analysis a hydrocarbon was found to consist of 81.8% carbon and 18.2% hydrogen. 7 % and 1 4. Each atom in the empirical formula has its own atomic weight. An unknown hydrocarbon has the molecular formula of C13H14. H present is 6 g. O present is 58 g. Then we can find the moles of each atom by dividing the mass from their molar masses. Guidelines for Naming Branched-Chain Hydrocarbons . This is the first in a series of 3 lessons about the interpretation of electron impact mass spectra. 5. O = 58 g/ 16 gmol -1 = 3.625 mol. Therefore in these 100 grams there are 85.7 g of carbon and 14.3 g of hydrogen. It has the molecular formula C10H16 and a UV absorption maximum at 232 nm. Mass of C = 13.96g CO2 12.01 g C 44.01g CO2 = 3.810 g C Mass of H = 5.72g H2O 2.016 g H 18.02g H2O = 0.6400 g H Mass of O = Mass of compound -Mass of C - Mass of H = (9.52 - 3.810 - 0.6400) g = 5.070 g Look atomic the given formula of the hydrocarbon and find out the (a) number of carbon atoms and (b) number of hydrogen atoms and proceed as follows: (i) If the number of hydrogen atoms is two more than double the number of carbon atoms, the not given hydrocarbons is an alekene. Answer: 17,48 g of CO2 contain 17,48/44 mol = x of CO2. Step 1 = 84/14 = 6 1 : Use this mass, algebra and the masses of carbon and hydrogen to solve for n (see example). An unknown hydrocarbon (A) with a molecular formula C9H16 reacts with H2 and Pd/C to yield B (C9H20). An unknown paraffinic hydrocarbon is defined by the chemical formula C_xH_2x + 2. A 0.2417g sample of a compound composed of C,H,O,Cl only, is burned in oxygen yielding 0.4964g of CO 2 and 0.0846g of H 2 O. For how to calculate the degree of unsaturation, the formula is given as: DU =. Furosemide glucuronide; Route of elimination. I should like to learn what that means. Use a degree-of-freedom analysis to determine how many variables must be specified to determine the flow rates of all components entering and leaving the combustion unit. Isotope abundance At this point it would be useful to reduce the number of possible formulas. Solution: 1a) Determine the grams of carbon in 0.3664 g CO 2 and the grams of hydrogen in 0.1500 g H 2 O. carbon: 0.3664 g x (12.011 g / 44.0098 g) = Main Menu. Indoxyl sulfate (potassium salt) is an agonist for the human aryl hydrocarbon receptor (AHR). Hence the empirical formula of the compound is C H X 2. Answer (1 of 2): Simple. C2H4O2. Combustion of a hydrocarbon with a molar mass of 78.11 g/mol produced 2.6406 g CO 2 and 0.5400 g H 2 O. Approximately 50% of the furosemide load is excreted unchanged in urine, and Answer (1 of 2): Since the emperical formula is given as CH2, in order to find the molecular formula of it you have to use the formula: N(the molar mass of emperical formula) = molar mass of compoundin this case, n(14)=70 Therefore, n=5 and thus, molecular formula will be, C5H10 Finally, multiply the ratio by two to get the smallest possible whole number subscripts while still maintaining the correct iron-to-oxygen ratio: 2(Fe1O1.5) =Fe2O3 2 ( Fe 1 O 1.5) = Fe 2 O 3. Add up the atomic masses of the atoms in the empirical formula. Enter the email address you signed up with and we'll email you a reset link. Since we do not know the formula we cannot balance the equation. Rule 1: Find the longest continuous C -chain and assign the root name. From this information, we can calculate the empirical formula of the original compound. Spiro[2.2]pentane is an alkane with two rings, so it is a cyclic alkane, with the general formula of CnH2(n+1-g).Below, we To get the formula of the hydrocarbon, we would need the size of a molecule or the number of basic formula items in a molecule. A periodic table will be required to complete this test. If you are given percent composition, you can directly convert the percentage of each element to grams. What is the molecular formula for this substance? Mass spectrometry therefore not only provides a specific molecular mass value, but it may also establish the molecular formula of an unknown compound. 1 dm3 of hydrocarbon A at 1 atmosphere pressure is shown to have a mass of 2.333g. a. What is the molecular formula for the hydrocarbon? 3. sugar is = C12 H22 O11 the molecular weight or molar mass is 342 g/mols. 2. step 5th:- Find the weight of empirical formula. Check Your Learning. What is the molecular formula of the unknown compound? The empirical formula is Fe 2 O 3. Check the carbonyl region at around 1650-1600 cm-1. 4. 4.finally we can determine the molecular formula for this hydrocarbon is C2H4.For detailed step-by-step discussion on how to determine the molecular formula of an unknown hydrocarbon from fuel analysis, see this Veho! Relative molecular mass of C H X 2 is 12 + 2 1 = 14. divide each mole with the lowest mole and round off to whole number, to give you the empirical formula. C = 36 g/ 12 gmol -1 = 3 mol. Olefins are produced at crude oil refineries and petrochemical plants and are not naturally occurring constituents of 27/18 =1.5 moles of water which is equivalent to 3 moles of H atoms (3g of H atoms) So the ratio of moles C atoms:H atoms = 2:3, so empirical formula = C2H3 and smallest molecular formula = C2H3. Add together the atomic weight of all atoms in the empirical formula. 10 How do you find the empirical formula quizlet? Re: molecular formula of hydrocarbon. to determine the molecular formula, just divide the molecular mass by the empirical mass. 70 14 = 5. Find out the molecular and empirical formula. Step 4th:- Write the empirical formula. 3 % respectively. This 10-question practice test deals with finding the molecular formula of chemical compounds. 5 Significantly more furosemide is excreted in urine following the I.V. the Avogadro's number is, 6.022 X 10^23. If a Lindlar's Test is run on this compound, 1 mole of hydrogen gas is consumed. The molecular formula is the representation of the actual whole number ratio between the elements of the compound. 14 What are the empirical formula and empirical formula mass for p2s5? (Molar mass of empirical formula) n = Molar mass of molecular formula Since the empirical formula of our compound is C 3 H 4 O 3 , it follows that its empirical formula molar mass is: (3 x 12.00g/mol) + (4 x 1.00 g/mol) + (3 x 16.00 g/mol) = 36.00 g/mol + 4.00 g/mol + 48.00 g/mol = 88.00 g/mol. 1. molar mass of NaOH is the sum total of individual elements molar Here is my work: C X a H X b C O X 2 + H X 2 O masses (g) 1.05 3.30 1.35. Stock Vector and explore similar vectors at Adobe Stock. has the molecular formula C3H10. Therefore Empirical Formula = CH2. It is burned completely under tightly controlled laboratory conditions (i.e., all products are recoverable, there are no side reactions, etc. If a KMnO4 test is also done on the unknown compound, CO2 gas bubbles are detected from the reaction vial. Your project is to determine the molecular formula of an unknown hydrocarbon (a compound consisting of only carbon and hydrogen). The answers are 5C, 1N, and 5H. If the unknown mixture contains none of the hydrocarbon H, the lowering of the freezing point will have its greatest Based on the above comparision, we have. Treatment of A with ozone followed by zinc and acetic acid yielded only acetone (C) and malonaldehyde (D). H X 2 O 2 H 18 g 2 g 1.35 g y. y = 0.15 g, moles of H = 0.15 1 = 0.15. empirical formula C X 0.075 / 0.075 H X 0.15 / 0.075 C H X 2. How many moles of CO 2 and H 2 O are generated ? For example, the empirical formula of a hydrocarbon is CH 2 and its M r is 42. The molecular weight is 194.19 g/mol. We have C:H = x:y and therefore, after dividing through the smaller of the both, a basic formula of CxHy. 1. The table on the right illustrates this important feature, and a double-focusing high-resolution mass spectrometer easily distinguishes ions having these compositions. An unknown paraffinic hydrocarbon is defined by the chemical formula $\mathrm{C}_{x} \mathrm{H}_{2 x+2}$. An unknown hydrocarbon (containing carbon and hydrogen) is found to have a molecular mass of 16 amu. A hydrocarbon of unknown structure (ooh, you're gonna LOVE OCII!!!) It is a process of burning hydrocarbons in the absence of excess oxygen and produces the most oxidized form of carbon which is carbon dioxide as a product. We'll learn how to calculate molecular formula for a compound when you are given its empirical formula and its molar mass. 9 What is the empirical formula of hydrocarbon 79.9 mass Carbon? If there is a difference between the mass of carbon and hydrogen versus the Two sets of hydrocarbons (Set A and Set B) were prepared. Divide the number of moles in each atom by the smallest number among them. 3. B) Reaction with Bromine 1. c=c c=c c formula molecular What is the empirical formula of this compound? All molecular formulas are inherently relative in From this information, we can calculate the empirical formula of the original compound. For example, a molecule has a molecular weight of 180.18 g/mol. 3. (a) Use the mass spectrum to propose a molecular formula. 7.14 : 14.3 7. The molecular formula of a compound is a representation of the number and type of elements present in one molecular unit of the compound. The empirical formula of a chemical compound is a representation of the simplest whole number ratio between the elements comprising the compound. However, to determine its molecular formula, it is necessary to know the molar mass of the compound. Calculate the molecular formula of the hydrocarbon. Go to the shop Go to the shop. This analysis was repeated with the two unknown liquids (unknown A and unknown B). )[l+B(t/-f/)] (7) and (8) Updated on August 01, 2019. mole=given mass/molar mass from this basic formula, given mass =mole*molar mass. 6. has the molecular formula C3H10. If x/y > 4 no hydrocarbon will exist. An unknown hydrocarbon has a molecular ion peak at m/e = 84, with a relative intensity of 31.3. Check out this video on the determination It is found to contain 40.00% carbon, 6.72% hydrogen and Converting to mole ratios. 4. The molecular weight of the unlmown is determined, if necessary, by measuring the lowering of the freezing point of another hydrocarbon, of the same type as the unknown mixture but which is not a component of the unknown mixture, on the addition to this other hydrocarbon of a measured small amount of the unknown. For laminar flow, where Re is < 2,000, there is little mixing of the flowing fluid, and the flow velocity is This step-by-step tutorial shows how to calculate the empirical and molecular formulas for a Rule 2: Assign the suffix based on the type of carbon -carbon bonds . Computational chemistry is a branch of chemistry that uses computer simulation to assist in solving chemical problems. injection than after the tablet or oral solution. The molecular formula is #"C"_3"H"_6"O"_3 Explanation: We must calculate the masses of C, H and O from the masses given. A separate 0.1696g sample of the compound is fused with sodium metal, the products dissolved in water and the chloride quantitatively precipitated with AgNO 3 to yield 0.1891g of AgCl. The M + 1 peak has a relative intensity of 2.06, and the M + 2 peak has a relative intensity of 0.08. The paraffin is burned with air, and there is no CO in the combustion products. Worked example: Determining an empirical formula from combustion data. Solution for 4. It is burned completely under tightly controlled laboratory conditions (Le, all products are recoverable, there are no side reactions, etc. Step 4: Check Masses. The M+1 peak has a relative intensity of 2.06, and the M+2 peak has a relative intensity of 0.08. You start by determining the empirical formula for the compound. Calculate the molecular formula of the hydrocarbon. Hence, the molecular formula of the hydrocarbon is CH 4. Hope the above explanation is useful to you. Do note that this is a very important concept when you are in JC1 and will still be tested when you are in JC2. C6H12. An unknown paraffinic hydrocarbon is defined by the chemical formula $\mathrm{C}_{x} \mathrm{H}_{2 x+2}$. A hydrocarbon of unknown structure (ooh, you're gonna LOVE OCII!!!) Look to the largest peak on your mass spectrum that does not include the halogen (molecular ion mass minus halogen mass). So, the empirical formula mass is 17.01 g/mol. The aryl hydrocarbon receptor (AhR) has recently emerged as a pathophysiological regulator of immune-inflammatory conditions and Indoxyl sulfate has been shown to be a ligand for AhR. Example #1: A 1.50 g sample of hydrocarbon undergoes complete combustion to produce 4.40 g Calculate the molecular formula of the hydrocarbon. Given that the molar volume of a gas at S.T.P (ie 25C, 1 atm) is 24 dm3. Solution for 4. 2. Once we know this value, coupled with the empirical formulas, we can easily calculate what the molecular formula is. H = 6 g/ 1 gmol -1 = 6 mol. This video explains the "CnH2n+2" pattern (and its variations) that we see in the molecular formulas of hydrocarbons. Sometimes questions will be about combuing analysis of other organic compounds too! Given relative molecular mass is 42. Empirical formulas can be determined from the percentage composition of a compound. The input values are an indication of the number of hydrogen atoms that should be present for the given compound to be classified as saturated. Therefore, the 5,73 grams contained x times 12 gram of carbon. The mass of the atoms in the empirical formula is 14 42 14 = 3 so you need to multiply the numbers in the empirical formula by 3 The molecular formula of the hydrocarbon is therefore C 3 H 6 . ), and the only available source of oxygen is a balloon inflated with pure METHOD Given an unknown mixture of hydrocarbons of similar type, it is required to determine the amount of a given hydrocarbon H which is in the unknown mixture. Measurement is made of the freezing point of a sample of "pure" H, and also the freezing point of a dilute solution of the unknown mixture in "pure" H. consisting all single bonds). C = 3/3. The ratio is 1.000 mol of iron to 1.500 mol of oxygen (Fe 1 O 1.5 ). Worked example: Determining an empirical formula from combustion data. It uses methods of theoretical chemistry, incorporated into computer programs, to calculate the structures and properties of molecules, groups of molecules, and solids.It is essential because, apart from relatively recent results concerning the hydrogen CO 2 : 0.733g / 44.009 g/mol = 16.66 mmol. Determining The Molecular Formula. Determine the mass in grams of each element in the sample. This division yields. You determine this number by finding the mass of HO (1 hydrogen atom and 1 oxygen atom). Rule 4: Assign a locator number to all substituents. and for H 2 O: 0.30g / 18.015g/mol = 16.66 mmol.. Remembering that the equation for a combustion reaction tells us that we will get 1mol 2 mol 1 mol. Notice that the carbon and oxygen mole numbers are the same, so you know the ratio of these two elements is 1:1 within the compound. Based on the molecular formula, determine whether each of the following is an alkane, alkene, or alkyne. ), and the only available source of oxygen is a balloon inflated with 88/44 =2 moles of CO2 which is equivalent to 2 moles of C atoms ( 2 x 12g C). Next, divide all the mole numbers by the smallest among them, which is 3.33. The paraffin is burned with air, and there is no CO in the combustion products. One way to do this is by looking at the intensity of the isotope peaks in the mass spectrum. Molecular Ion: EI Requirements for the Molecular Ion Must be the highest m/z peak in the spectrum Highest Isotope Cluster Must be an odd-electron ion High mass fragments must be explained must come from logical neutral losses These are necessary but insufficient conditions for molecular ion identification The molecular formula is often the same as an empirical formula or an exact multiple of it. Calculate the empirical formula mass. C x H y (g) + (x + y/4) O 2 (g) > xCO 2 (g) + y/2 H 2 O (l) 10cm 3 20cm 3 .10cm 3. (c) Propose one or more structures for this compound. We have a hint: The hydrocarbon richest of H is CH4. The complete balanced combustion reactions were written down for each of the known chemicals used in this experiment. Calculate the empirical formula by saying 80% of 30(your Mr which is a summation of all atoms' At that are in the Hydrocarbon) and the answer you get is your carbon content.