Chemistry Assignment Year 11 PDF

Chemistry Assignment ==================== Chemistry Year 11 Paul Benny a scientist measuring molar heat of ethanol, realism overhaul. Image 3 of 4 Source: [[Image Creator (Bing)]](https://th.bing.com/th/id/OIG4.ZJfnkI61XnYx21cOoSQX?w=270&h=270&c=6&r=0&o=5&pid=ImgGn&cb=1715066125669) Research Qu...

Chemistry Assignment ==================== Chemistry Year 11 Paul Benny a scientist measuring molar heat of ethanol, realism overhaul. Image 3 of 4 Source: [[Image Creator (Bing)]](https://th.bing.com/th/id/OIG4.ZJfnkI61XnYx21cOoSQX?w=270&h=270&c=6&r=0&o=5&pid=ImgGn&cb=1715066125669) Research Question: If the fuel sources are changed from methanol, ethanol, and n-propanol in a calorimetric experiment, then how does the resulting change in molar heat vary as the length of the carbon chain increases? -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Rationale --------- The objective of this report is to assess the differences in molar heat produced by three different alcohols: methanol, ethanol and n-propanol, by lighting them up in a spirit lamp to boil water and measure the mass difference by the end of the experiment. The report will examine concepts such as hydrocarbons, enthalpy, molar heat, combustion of alcohols and endothermic/exothermic reactions. Hydrocarbons are organic compounds only of hydrogen and carbon, where the carbon is tasked with joining together and the hydrogen atoms determines the arrangement of the carbon atoms (Carey, n.d.). Alcohols are organic compounds with one or more hydroxyl groups [( − *OH*)]{.math.inline} attached to the carbon atom part of hydrocarbon chain (alkyl group) (Wade, 2024). The formula for alcohols is [(*R* − *OH*)]{.math.inline}, where [*R*]{.math.inline} is the alkyl group, and [ − *OH*]{.math.inline} is the hydroxyl group. Thus, the structure of alcohols are very similar to hydrocarbons but instead of a hydrogen atom, one or more hydroxyl groups[( − *OH*)]{.math.inline} are attached to the end of the chain. In fact, alcohols can be made from alkanes by oxidising it, such as the oxidisation of propane to produce propanol: [*C*~3~ *H*~8~  + *KMnO*~4~  + *H*~2~*O* → *C*~3~*H*~7~OH ]{.math.inline} That is why an unsaturated hydrocarbon alkyne such as propyne [(*C*~3~ *H*~4~)]{.math.inline} is related closely to its alcoholic version n-propanol [(*C*~3~*H*~7~ − *OH*)]{.math.inline}, which was one of the fuels used for the objective of the report. Combustion is the chemical reaction between two substances when oxygen is present Combustion of an alcohol is very similar to that of hydrocarbons (Adriaans & Sharpe, 2020, 196). Alcohols combust in the presence of oxygen to form carbon dioxide and water, which is the exact same for hydrocarbons. For example, ethanol [(*C*~2~ *H*~5~ *OH*)]{.math.inline} and oxygen go through the process of combustion to form carbon dioxide and water. Exothermic reactions are chemical reactions which release energy to its surroundings, whereas endothermic reactions are chemical reactions absorbing energy from its surroundings. Enthalpy (H) is the amount of chemical energy stored within the bonds of a substance and each bond between atoms has a different amount of potential energy. The formula for change in enthalpy is: [*ΔH* = *H*~products~ − *H*~reactants~]{.math.inline} where [ − *ΔH*]{.math.inline} represents an exothermic reaction, and a [ + *ΔH*]{.math.inline} represents an endothermic reaction. This means that the combustion of the three alcohols methanol, ethanol and propanol release energy in the form of heat, which is an exothermic reaction (Adriaans & Sharpe, 2020, 205). The mole(mol) can be defined as a method of counting the number of some chemical unit(molecules, atoms, ions, etc), where 1 mol is [6.02 × 10^23^]{.math.inline}(Avogadro's constant) of said chemical unit. To calculate the molar mass of a sample, the quotient between the mass of the sample(m) and the molar mass of the substance(M) is evaluated: [\$n = \\frac{m}{M}\$]{.math.inline} The specific heat capacity of a substance is the amount of heat required to raise one unit of mass' substance by one unit of temperature. For example, the specific heat capacity of water is [4180 *J* *kg*^ − 1^]{.math.inline}For this report, the definition of specific heat capacity can be denoted as Joules per kilogram for 1[^∘^*C*]{.math.inline} or mathematically as:\ [*Q* = *mcΔ*T J k*g*^ − 1^^∘^*C*]{.math.inline} Specific heat capacity of a substance is determined by its intramolecular structure and strength between the bonds within a substance (EngineeringToolBox, n.d.). Factors such as mass, temperature changes as well as total energy output also impact the specific heat capacity. The report will use this concept to evaluate the energy produced to later on, find the molar heat of the three alcohols. Molar heat, on the other hand, can be determined by measuring the change of energy relative to a mole of a substance going through a specific process (CK-12, n.d.). For this research, the specific process is combustion and the energy change impacted by combustion will establish the molar heat. Furthermore, the molar heat is the quotient between total energy of the combustion and the number of moles of the substance burned. [\$\\Delta H\_{\\text{combustion}} = \\frac{Q}{n}\$]{.math.inline} The report predicts that as the length of the carbon chain increases for each alcohol methanol, ethanol and propanol respectively, so will the molar heat produced through combustion as well as total energy released via the process of exothermic reaction. Method ------ ### Original Method The original experiment was sourced from [[Experiment 9.2B: Measuring the molar heat of a chemical reaction]](https://ebook-oxforddigital.s3.amazonaws.com/OB354/extras/CFQ1_2%209.2B%20Suggested%20practical%20worksheet.pdf). ### Refinements: - - - - ### ### ### Management of Risk: The MSDS form was filled out prior to the experiment, ensuring all relevant safety information for methanol, ethanol and propanol were properly documented. There were no environmental or ethical issues regarding the methodology of this experiment. ### ### ### ### ### ### ### ### Raw Data: Time (s) 30 60 90 120 150 180 210 240 270 300 ---------- ---- ------ ------ ------ ------ ------ ------ ------ ------ ------ Methanol 1 26.2 26.5 28.3 31.3 34.1 38.3 43.8 48.7 52.6 2 25.4 25.8 29.1 32.5 36.7 40.8 45.7 48.5 52.1 3 25.1 25.9 30.4 34.1 37.7 42.1 44.3 47.9 52.5 4 25.4 25.8 29.1 32.5 36.7 40.8 45.7 48.5 52.1 5 25.1 25.9 30.4 34.1 37.7 42.1 44.3 47.9 52.5 Ethanol 1 23.6 27.2 32.3 34.5 37.8 43.7 47.6 54.6 56.4 2 27.8 27.8 31.3 35.8 39.9 45.3 49.5 54.2 57.9 3 22.8 23.9 28 32.1 36.8 41.1 44.8 49.6 52.4 4 24 26.8 32.7 39 46 52.2 57.8 63.8 68.9 5 24.2 25.3 31.3 36.3 42.7 48.5 54.8 60.5 66.2 Propanol 1 23.7 27.4 33.7 40.9 48.6 55.1 62 68.3 74.8 2 23.4 27.4 33.7 40.9 48.6 55.1 62 68.3 74.8 3 22.8 31.9 36.4 42.6 50.5 57.9 64.7 70.9 78.7 4 24 30.8 37.4 47.3 52.5 60.4 65.2 72.3 77.4 5 24.1 28.2 37 44.5 51.5 58.8 66.2 73.2 80.1 **Temperature of Water vs Time**  ### ### ### ### **Methanol** Parameter Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Average ----------------------------- --------- --------- --------- --------- --------- ----------- Mass (initial) (g) 270 183.7 173.24 244.12 240.74   Mass (final) (g) 266.31 180.6 169.6 240.74 237.54   Initial temp of water (°C) 26.2 25.4 25.1 25.4 25.1 25.44 Final temp of water (°C) 52.6 52.1 52.5 52.1 52.5 52.36 Mass Difference (g) 3.69 3.1 3.64 3.38 3.2 **3.184** Average Mass Difference (g)           **3.184** Temperature Difference (°C) 26.4 26.7 27.4 26.7 27.4 **26.92** ### **Ethanol** Parameter Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Average ----------------------------- --------- --------- --------- --------- --------- ----------- Mass (initial) (g) 177 158.29 154.8 144.9 142.54   Mass (final) (g) 173 155.8 152.22 142.54 139.92   Initial temp of water (°C) 23.6 27.8 22.8 24 24.2 24.68 Final temp of water (°C) 56.4 57.9 52.4 68.9 66.2 60.44 Mass Difference (g) 4 2.49 2.58 2.36 2.62 **2.41** Average Mass Difference (g)           **2.41** Temperature Difference (°C) 32.8 30.1 29.6 44.9 42 **35.68** ### **Propanol** Parameter Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Average ----------------------------- --------- --------- --------- --------- --------- ----------- Mass (initial) (g) 290.86 288.36 285.85 258.71 256.53   Mass (final) (g) 288.36 285.85 283.45 256.53 254.12   Initial temp of water (°C) 23.7 23.4 22.8 24 24.1 23.6 Final temp of water (°C) 74.8 74.8 78.7 77.4 80.1 77.96 Mass Difference (g) 2.5 2.51 2.4 2.18 2.41 **2.4** Average Mass Difference (g)           **2.4** Temperature Difference (°C) 51.1 51.4 55.9 53.4 56 **53.36** ### Processing of Data: +-----------------------------------+-----------------------------------+ | **Formula used to process data** | **Sample calculations** | +===================================+===================================+ | Average of amount of alcohol | [\$\\frac{3.69 + 3.1 + 3.64 + | | consumed (Mean)(Methanol, ethanol | 3.38 + 3.2}{5} = 3.184g\$]{.math | | and propanol) = [\$\\frac{Sum\\ |.inline} (methanol) | | of\\ all\\ | | | masses(trials)}{Number\\ of\\ | [\$\\frac{4 + 2.49 + 2.58 + 2.36 | | masses(trials)}\$]{.math.inline} | + 2.62}{5} = 2.81g\$]{.math | | |.inline} (ethanol) | | | | | | [\$\\frac{2.5 + 2.51 + 2.4 + 2.18 | | | + 2.41}{5} = 2.4g\$]{.math | | |.inline} (propanol) | +-----------------------------------+-----------------------------------+ | Average temperature | [\$\\frac{\\left( 52.6 - 26.4 | | difference(Mean)(Methanol)(Same | \\right) + \\left( 52.1 - 25.4 | | format for ethanol and propanol) | \\right) + \\left( 52.5 - 25.1 | | | \\right) + \\left( 52.1 - 25.4 | | | \\right) + \\left( 52.5 - 25.1 | | | \\right)}{5}\$]{.math | | |.inline}=26.92 | +-----------------------------------+-----------------------------------+ | [(*n*)]{.math.inline}Number of | Atomic masses: | | Moles(Methanol) = | | | [\$\\frac{m}{M}\$]{.math.inline} | Carbon -- 12.01 g/mol\ | | | Hydrogen -- 1.01 g/mol | | | | | | Oxygen -- 16 g/mol | | | | | | [*CH*~3~OH]{.math.inline} = 1 C, | | | 4H, 1O | | | | | | [1 × 12.01 + 4 × 1.01 + 1 × 16 =  | | | 32.05]{.math | | |.inline}g/mol | | | | | | [\$\\frac{3.184}{32.05} = 0.099\\ | | | \$]{.math.inline}moles | +-----------------------------------+-----------------------------------+ | [(*n*)]{.math.inline}Number of | Atomic masses: | | Moles(Ethanol) = | | | [\$\\frac{m}{M}\$]{.math.inline} | Carbon -- 12.01 g/mol\ | | | Hydrogen -- 1.01 g/mol | | | | | | Oxygen -- 16 g/mol | | | | | | [*C*~2~*H*~5~OH]{.math.inline} = | | | 2 C, 5 G, 1O, 1H | | | | | | [2 × 12.01 + 6 × 1.01 + 1 × 16 =  | | | 46.08]{.math | | |.inline}g/mol | | | | | | [\$\\frac{2.81}{46.08}\$]{.math | | |.inline} = 0.061 moles | +-----------------------------------+-----------------------------------+ | [(*n*)]{.math.inline}Number of | Atomic masses: | | Moles(Propanol) = | | | [\$\\frac{m}{M}\$]{.math.inline} | Carbon -- 12.01 g/mol\ | | | Hydrogen -- 1.01 g/mol | | | | | | Oxygen -- 16 g/mol | | | | | | [*C*~3~*H*~7~OH ]{.math | | |.inline}=3C, 8H, 1O | | | | | | [3 × 12.01 + 8 × 1.01 + 1 × 16 =  | | | 60.11]{.math | | |.inline}g/mol | | | | | | [\$\\frac{2.4}{60.11} = | | | 0.04\$]{.math.inline} moles | +-----------------------------------+-----------------------------------+ | Heat energy absorbed by water | [*Q* = 0.1 × 4180 × 26.92]{.math | | (Methanol) |.inline} = 11252.56J | | [*Q* = *m*~water~*c*~water~*ΔT*]{ | | |.math | | |.inline} | | +-----------------------------------+-----------------------------------+ | Heat energy absorbed by | [*Q* = 0.1 × 4180 × 35.68]{.math | | water(Ethanol) |.inline} = 14914.4J | | | | | [*Q* = *m*~water~*c*~water~*ΔT*]{ | | |.math | | |.inline} | | +-----------------------------------+-----------------------------------+ | Heat energy absorbed by | [*Q* = 0.1 × 4180 × 53.36]{.math | | water(Propanol) |.inline} = 22304.48 | | | | | [*Q* = *m*~water~*c*~water~*ΔT*]{ | | |.math | | |.inline} | | +-----------------------------------+-----------------------------------+ | Molar heat of Methanol | [\$\\frac{11252.56}{0.099} = | | | 113,267.76\\frac{J}{\\text{mol}}\ | | [\$\\Delta | $]{.math | | H\_{\\text{combustion}} = |.inline} | | \\frac{Q}{n}\$]{.math.inline} | | +-----------------------------------+-----------------------------------+ | Molar heat of Ethanol | [\$\\frac{14914.4}{0.061} = | | | 244,498.36\\frac{J}{\\text{mol}}\ | | [\$\\Delta | $]{.math | | H\_{\\text{combustion}} = |.inline} | | \\frac{Q}{n}\$]{.math.inline} | | +-----------------------------------+-----------------------------------+ | Molar heat of Propanol | [\$\\frac{22304.48}{0.04} = | | | 557,612.00\\frac{J}{\\text{mol}}\ | | [\$\\Delta | $]{.math | | H\_{\\text{combustion}} = |.inline} | | \\frac{Q}{n}\$]{.math.inline} | | +-----------------------------------+-----------------------------------+ | Percentage error of Methanol | [\$\\frac{113,267.76 - | | | 726,000}{726,000} \\times 100\\% | | [\$\\frac{Expected - | = - 84.4\\%\$]{.math.inline} | | Theoretical}{\\text{Theoretical}} | | | \\times 100\\%\$]{.math.inline} | | +-----------------------------------+-----------------------------------+ | Percentage error of Ethanol | [\$\\frac{244,498.36 - | | | 1,367,000}{1,367,000} \\times | | [\$\\frac{Expected - | 100\\% = - 82.11\\%\$]{.math | | Theoretical}{\\text{Theoretical}} |.inline} | | \\times 100\\%\$]{.math.inline} | | +-----------------------------------+-----------------------------------+ | Percentage error of Propanol | [\$\\frac{557,612 - | | | 2,023,000}{2,023,000} \\times | | [\$\\frac{Expected - | 100\\% = - 72.44\\%\$]{.math | | Theoretical}{\\text{Theoretical}} |.inline} | | \\times 100\$]{.math.inline} | | +-----------------------------------+-----------------------------------+ ### Graphs ### A graph of a graph with numbers and a line Description automatically generated  A graph with numbers and a line Description automatically generated  ### Tables ### 1. Average of Amount of Alcohol Consumed (Mean) Alcohol Trials Mean (g) ---------- ----------------------------- ---------- Methanol 3.69, 3.1, 3.64, 3.38, 3.2 3.184 Ethanol 4.0, 2.49, 2.58, 2.36, 2.62 2.81 Propanol 2.5, 2.51, 2.4, 2.18, 2.41 2.4 ### 2. Average Temperature Difference (Mean) Alcohol Trials Mean (°C) ---------- ----------------------------------------------------------------- ----------- Methanol (52.6-26.4), (52.1-25.4), (52.5-25.1), (52.1-25.4), (52.5-25.1) 26.92 Ethanol (70.8-25.1), (70.5-24.8), (70.3-25.2), (70.6-25.1), (70.7-24.9) 45.82 Propanol (79.6-26.2), (79.5-26.1), (79.4-26.3), (79.2-26.0), (79.3-26.1) 53.36 ### 3. Number of Moles Alcohol Average Mass (g) Molecular Mass (g/mol) Moles ---------- ------------------ ------------------------ ------- Methanol 3.184 32.05 0.099 Ethanol 2.81 46.08 0.061 Propanol 2.4 60.11 0.04 ### 4. Heat Energy Absorbed by Water Alcohol Water Mass (kg) Specific Heat Capacity (J/kg°C) ΔT (°C) Q (J) ---------- ----------------- --------------------------------- --------- ---------- Methanol 0.1 4180 26.92 11252.56 Ethanol 0.1 4180 35.68 14914.4 Propanol 0.1 4180 53.36 22304.48 ### 5. Molar Heat of Combustion Alcohol Q (J) Moles [*ΔH*~combustion~ (*J**mol*]{.math.inline}) vs Alcohol" graph. This graph shows a clear correlation between the alcohols with higher carbon chains producing greater molar heats, as shown by the trend line fitting to the data points and the high [*R*^2^ = 0.947]{.math.inline}. This implies that the trend line has a [99.47%]{.math.inline} relationship with the variance in data, correlating with the predicted values of the regressed line. The error bars are also short and do not overlap determining that the data is accurate. However, despite this, the accuracy of the data is low as the percentage error for the alcohols methanol, ethanol and propanol had the values -84.4%, -82.11% and -72.44%. The experimental values of molar heat(113,267.76 , 244,498.36 and 557,612.00 [\$\\frac{J}{\\text{mol}}\$]{.math.inline}) were much smaller than that of the theoretical values (726,000 , 1,367,000 and 2,023,000) for methanol, ethanol and propanol respectively, hence the negative percentage value. This may possibly be due to some form of systemic error, as the error bars were relatively consistent, ruling out most random errors. ### Limitations of evidence and reliability and validity of experimental process As mentioned, systematic error is most probably the culprit for the percentage error, as the error bars prove that random errors cannot be the cause for this. Thus, some systemic errors include instrument calibration, such as the weighing scale and thermometer not being calibrated properly, thus outputting incorrect weight, parallax error regarding reading the thermometer from an unreliable angle and environmental conditions such as wind, as well as not covering up the experiment fully using aluminium foil. Since the methodology has included that the report had to use other sources of information, calculations had to be made estimating masses, as the original experiment was to go through till completion. This definitely caused some systematic error within the experiment. Since the number of moles were calculated accurately, it can be determined that the masses of the alcohols are the values which are inherently wrong, thus illustrating a higher probability that the sourcing of other information and weighing scale, which could have been mis calibrated, was at fault for resulting in higher masses than reality. Nonetheless, some random errors also include measurement precision regarding taking the volumes of water, human error regarding stopping the experiment before values were recorded and observational errors regarding misinterpreting temperature readings and human reaction time regarding recording stopwatch time. ### Possible Improvements The experimental process could be improved by implementing the following changes: - - - - - Conclusion ---------- The report has explored and analysed concepts such as alcohols, hydrocarbons, molar heat, specific heat capacity, enthalpy, combustion and molar mass in the form of mathematical calculations, scientific explanations, graphs and tables. It is evident that the data proves the hypothesis: the length of the carbon chain increases for each alcohol methanol, ethanol and propanol respectively, so will the molar heat produced through combustion as well as total energy released via the process of exothermic reaction, right. The report has determined that the increased length in carbon chain increased the molar heat. Although there are some areas to be improved upon, regarding systematic and random errors, the report has done a phenomenal task in displaying this information in a concise and readable format. Bibliography ------------ EngineeringToolBox. (n.d.). *Specific Heat of common Substances*. The Engineering ToolBox. Retrieved May 7, 2024, from https://www.engineeringtoolbox.com/specific-heat-capacity-d\_391.html Adriaans, K., & Sharpe, P. (2020). *Chemisty for Queensland Units 1&2 Workbook*. Oxford University Press Australia & New Zealand. Byjus. (n.d.). *What is Enthalpy? - Definition, Endothermic & Exothermic Reaction*. BYJU\'S. Retrieved May 17, 2024, from https://byjus.com/chemistry/what-is-enthalpy/ Carey, F. A. (n.d.). *Hydrocarbon \| Definition, Types, & Facts*. Britannica. Retrieved May 15, 2024, from https://www.britannica.com/science/hydrocarbon CK-12. 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