## Saturday, March 14, 2020

### An experiment to determine the enthalpy changes using Hesss law Essay Example

An experiment to determine the enthalpy changes using Hesss law Essay Example An experiment to determine the enthalpy changes using Hesss law Essay An experiment to determine the enthalpy changes using Hesss law Essay The main idea behind this experiment is to find out the temperature difference between the room temperature and the final temperature. Sodium carbonate, sodium hydrogencarbonate and hydrochloric acid were used in this experiment. Sodium carbonate, also known as soda ash is got from the reaction of carbonic acid and sodium hydroxide while sodium hydrogencarbonate (baking soda) is a salt formed by the partial replacement of hydrogen by sodium.Data Collection1) Temperature change by using 3.3g of sodium hydrogencarbonateMass of the container on which the sample was weighed = 11.48gMass of the container and the crystals = 14.98gMass of the container after the crystals were added = 11.70gMass of the crystals that did not react = 00.20gMass of the crystals that reacted = 03.30gTime (s)Temperature ( Ãƒ ¯Ã‚ ¿Ã‚ ½ C)023.03023.06023.09018.012015.015015.018015.021015.024015.527016.030016.02) Temperature change by using 1.88g of sodium carbonateMass of the container on which the sample was weigh ed = 11.48gMass of the container and the crystals = 13.48gMass of the container after the crystals were added = 13.60gMass of the crystals that did not react = 00.12gMass of the crystals that reacted = 01.88gTime (s)Temperature ( Ãƒ ¯Ã‚ ¿Ã‚ ½ C)023.03023.06023.09029.012030.015030.018030.021030.024029.527029.030029.03) Temperature change by using 5.66g of sodium hydrogencarbonateMass of the container on which the sample was weighed = 11.48gMass of the container and the crystals = 18.48gMass of the container after the crystals were added = 12.82gMass of the crystals that did not react = 01.34gMass of the crystals that reacted = 05.66gTime (s)Temperature ( Ãƒ ¯Ã‚ ¿Ã‚ ½ C)023.03023.06023.09021.012021.015021.018021.021021.024022.527022.030022.04) Temperature change by using 3.85g of sodium carbonateMass of the container on which the sample was weighed = 11.48gMass of the container and the crystals = 15.48gMass of the container after the crystals were added = 11.63gMass of the crystals th at did not react = 00.15gMass of the crystals that reacted = 03.85gTime (s)Temperature ( Ãƒ ¯Ã‚ ¿Ã‚ ½ C)023.03023.06023.09028.512028.515028.518028.521028.524028.027028.030028.0UNCERTAINITIES+/- 0.01g : Digital weighing scale+/- 0.01s : Stop watch+/- 0.05cm3 : Measuring cylinder+/- 0.05Ãƒ ¯Ã‚ ¿Ã‚ ½C : ThermometerOBSERVATIONS- When hydrochloric acid is added to sodium carbonate, some effervescence (bubbles appear) is observed because of the liberation of carbon dioxide gas. It is completely soluble and in the process it starts getting warmer.- The same thing happens when sodium hydrogencarbonate is added to hydrochloric acid except for the fact it cools down instead of getting warmer.CHEMICALS (QUALITATIVE DATA)1) Hydrochloric acid- It is colorless and odorless. It is a monoprotic acid, that is, it produces 1 hydrogen ion when completely dissolved in water. The molarity of hydrochloric acid used in this experiment is 2M.2) Sodium carbonate- Sodium Carbonate is a white, crystalline com pound soluble in water (absorbing moisture from the air) but insoluble in alcohol. It forms a strongly alkaline water solution. It is also known as soda ash3) Sodium hydrogencarbonate- sodium bicarbonate or sodium hydrogen carbonate, chemical compound, NaHCO3, a white crystalline or granular powder, commonly known as bicarbonate of soda or baking soda. It is soluble in water and very slightly soluble in alcohol.DATA PROCESSING AND PRESENTATIONFinding the enthalpy of reaction for the following equation:2NaHCO3 Na2CO3 + H2O +CO2a) Using 1.88g of sodium carbonate and 3.3g of sodium hydrogencarbonateEnthalpy cycle for the reaction?H12NaHCO3(s) + 2 HCl 2NaCl(aq) +2 CO2(g)+ 2 H2O(l)?H2 ?H3Na2CO3(s) + CO2(g) + H2O + 2 HCL(aq)Heat released during the reaction between HCl and NaHCO3 (Q1)= Mc?TSo, Q1 = 25g * 4.18 * (15-23)Q1 = 25* 4.18 * -8Therefore, Q1 = -836 J= -0.836KJCalculating the number of moles present in 3.3g of NaHCO3Number of moles = mass(g)/ molar massMass (g) = 3.3gMolar mass = 2 3 + 1 + 12 +(16*3)= 23 + 1 + 12 + 48= 84 g/molnumber of moles present in 3.3g of NaHCO3 = 3.3g/ (84g/mol)= 0.039 molesCalculating the amount of energy given out by 1 moleIf 0.039 moles of NaHCO3 give -0.836KJ of energy then1 mole would give out (-0.836/0.039 = -21.44KJ) of energyTherefore, ?H1 = -21.44 KJ/molCalculating ?H3 by the above method, that is, the reaction between Na2CO3 and HClQ2 = Mc?TSo, Q2 = 25 * 4.18 * (30-23)Q2 = 25 * 4.18 * 7Therefore, Q2 = 731.5J= 0.7315KJCalculating the number of moles present in 1.8g of Na2CO3Number of moles = mass (g)/ molar massMass (g) = 1.8gMolar mass = (23 * 2) + 12 +(16*3)= 46 +12 + 48= 106 g/molnumber of moles present in 1.8g of Na2CO3 = 1.8g/ (106g/mol)= 0.018 molesCalculating the amount of energy given out by 1 moleIf 0.018 moles of Na2CO3 give -0.731KJ of energy then1 mole would give out (-0.7315/0.018 = 40.64KJ) of energyTherefore, ?H3 = 40.64 KJ/molIn order to find the enthalpy of reaction for:2NaHCO3 Na2CO3 + H2O+ CO2; we use the Hes ss law which states that 2 ?H1 = ?H2 + ?H3?H2 = 2 ?H1 ?H3so, 2 ?H1 = 2 * -21.44 KJ/mol= -42.88KJ/mol?H3 = 40.64 KJ/molTherefore, ?H2 = -42.88 40.64= -83.52KJ/molb) Calculating the enthalpy change of reaction using 5.66g of sodium hydrogencarbonate, 3.85g of sodium carbonate and 50cmÃƒ ¯Ã‚ ¿Ã‚ ½ of HCl.Enthalpy cycle for the reaction?H12NaHCO3(s) + 2 HCl 2NaCl(aq) +2 CO2(g)+ 2 H2O(l)?H2 ?H3Na2CO3(s) + CO2(g) + H2O + 2 HCL(aq)Heat released during the reaction between HCl and NaHCO3 (Q1)= Mc?TSo, Q1 = 50g * 4.18 * (21.5-23.0)Q1 = 50* 4.18 * 1.5Therefore, Q1 = -331.50 J= -0.3135KJ `Calculating the number of moles present in 5.66g of NaHCO3Number of moles = mass (g)/ molar massMass (g) = 5.66gMolar mass = 23 + 1 + 12 + (16*3)= 23 + 1 + 12 + 48= 84 g/molnumber of moles present in 5.66g of NaHCO3 = 5.66g/ (84g/mol)= 0.0674 molesCalculating the amount of energy given out by 1 moleIf 0.0674 moles of Na2CO3 give -0.3135KJ of energy then1 mole would give out (-0.3135/0.0674 = -4.65KJ) of en ergyTherefore, ?H1 = -4.65 KJ/molCalculating ?H3 by the above method, that is, the reaction between Na2CO3 and HClQ2 = Mc?TSo, Q2 = 50 * 4.18 * (28.5-23)Q2 = 50 * 4.18 * 5.5Therefore, Q2 = 1149.5J= 1.1495KJCalculating the number of moles present in 3.85g of Na2CO3Number of moles = mass (g)/ molar massMass (g) = 3.85gMolar mass = (23 * 2) + 12 + (16*3)= 46 +12 + 48= 106 g/molnumber of moles present in 1.8g of Na2CO3 = 3.85g/ (106g/mol)= 0.036 molesCalculating the amount of energy given out by 1 moleIf 0.036 moles of Na2CO3 give 1.1495KJ of energy then1 mole would give out (1.1495KJ/0.036 = 31.93KJ) of energyTherefore, ?H3 = 31.93KJ/molIn order to find the enthalpy of reaction for:2NaHCO3 Na2CO3 + H2O+ CO2; we use the Hesss law which states that 2 ?H1 = ?H2 + ?H3?H2 = 2 ?H1 ?H3so, 2 ?H1 = 2 * -4.65 KJ/mol= -9.3KJ/mol?H3 = 31.93KJ/molTherefore, ?H2 = -9.3KJ/mol 31.93KJ/mol= -41.23KJ/molc) Error analysisDigital weighing scale: 1) 0.01/3.3 * 100= Ãƒ ¯Ã‚ ¿Ã‚ ½0.3%2) 0.01/5.66 * 100= Ãƒ ¯Ã‚ ¿Ã‚ ½0.18%Stop watch : 0.01/300 * 100= Ãƒ ¯Ã‚ ¿Ã‚ ½ 3.3*10^-3Measuring cylinder : 1) 0.05/25 * 100= Ãƒ ¯Ã‚ ¿Ã‚ ½0.2%2) 0.05/50 * 100= Ãƒ ¯Ã‚ ¿Ã‚ ½0.1%Thermometer : 0.05/23 * 100= Ãƒ ¯Ã‚ ¿Ã‚ ½0.22%Total percentage error = 0.22%+ 0.1% + 3.3*10^-3 + 0.18%+ 0.3%= Ãƒ ¯Ã‚ ¿Ã‚ ½0.8033%Accounting for the error ?H2 = Ãƒ ¯Ã‚ ¿Ã‚ ½ -41.23KJ/mol= Ãƒ ¯Ã‚ ¿Ã‚ ½ -83.52KJ/molConclusionThe reaction between sodium hydrogencarbonate and HCl is endothermic, that is, heat is being absorbed in the reaction and the reaction between sodium carbonate and HCl is exothermic because temperature is given out to the surroundings.Also, in the second part of the experiment when the volume of HCl is increased and also the masses of sodium hydrogencarbonate andsodium carbonate is increased, the temperature difference in the reaction is less than before when the mass were less. The enthalpy of reaction is also decreased in the second part.Evaluation:Reasons for shortcoming in the answers are as follows:1) While t ransferring the HCl from the measuring cylinder to beaker, there is a possibility of leaving out some amount of HCl in the beaker itself.2) An analogue thermometer was used so the temperature may not have been accurate.3) Some systematic errors in the equipment might have led to some slight changes in the readings.Solution to the above problems:1) The first problem stated above is a personal error; So it can only be overcome by practice and improving ones concentration while doing the experiment.2) The second problem could have been overcome by the use of digital thermometer which is more accurate than an analogue thermometer.

## Wednesday, February 26, 2020

### Business Submission Assignment Example | Topics and Well Written Essays - 1500 words

Business Submission - Assignment Example In compliance with Principle 1, our organization has several initiatives in place such as a response process to deal with any employee who may have any grievances pertaining to the violation of their human rights. In addition, we view employees as important assets and hence free communication is fully supported by the management giving the employees an opportunity to air any views that they may have. Principle 8 PracticesEver since our invention, we have been operating under the notion of prevailing in concert with the environment rather than be at odds with it. As compared to other data centers globally, our data centers save up to 50% on energy which is a rather big achievement given how very few companies consider this.We encourage employees to take part in environmental responsiveness via implementing practices that target waste reduction, recycling, and reusing. For instance, we host farmersÃ¢â‚¬â„¢ markets and sustainable cooking seminars as a way of setting an example to the e mployees on Ã¢â‚¬Å"going greenÃ¢â‚¬ . Currently, our facilities are powered by renewable energy. We have taken the initiative to invest in renewable energy projects that help us take part in minimizing the impact of carbon dioxide on the rest of the world.Given that we are highly involved in practices that comply with principles 1 and 8 of the Un Global Compact principles, we believe that are capable of endorsing recommendations that will guide other businesses in compliance with these Global Compact Principles.

## Monday, February 10, 2020

### Anything But Lazy Essay Example | Topics and Well Written Essays - 500 words

Anything But Lazy - Essay Example In order to examine the effects of these factors, the author undertook a study which examined how middle school students undertake the "reading task demands of his or her classroom" and how each teacher contributed to the students' reading task / challenge. Using a descriptive case study approach, the author conducted periodic visits, administered questionnaires and conducted comprehension assessments in order to gather primary data. Identifying themes and patterns from an analysis of this data, the author identified "the ways in which each student transacted in the classroom and how the teachers worked with / responded to students around issues of reading and comprehension". The study revealed that as far as students were concerned, their reading / comprehension was influenced by own ability, desire to learn, and more importantly, how the student wanted to be perceived [by his or her peers] as a reader.

## Wednesday, January 22, 2020

### MIC conviction :: Essays Papers

MIC conviction Introduction Three aviation students with similar cases involving Minor in Consumption charges will be discussed. The three students are Mr. Jack Daniels, Mr. Johnnie Walker, and Ms. Brandy Wine. We will look at each student separately and answer questions pertaining to each of their situations. Some of the questions include whether or not the students need to comply with the reporting requirement of 14 CFR Ã‚ § 61.15. What, if any, reports do they have to make on their next medical? We will also discuss Ms. WineÃ¢â‚¬â„¢s situation, whether or not the police stop violated the Fourth Amendment. Mr. Jack Daniels Mr. Daniels was cited for Minor in Consumption of Alcohol, pled guilty, and was sentenced to pay a \$100 fine. Mr. Daniels wants to know what he needs to do to comply with the FAA so that he can remain a pilot. According to 14 CFR Ã‚ §61.15(e), Ã¢â‚¬Å"Each person holding a certificate issued under this part shall provide a written report of each motor vehicle action to the FAA . . . no later than 60 days after the motor vehicle action.Ã¢â‚¬  To determine whether Mr. Daniels must comply with this regulation, a Ã¢â‚¬Å"motor vehicle actionÃ¢â‚¬  must be defined. As per 14 CFR Ã‚ §61.15(c), a motor vehicle action means: (1) A conviction after November 29, 1990, for the violation of any Federal or State statute relating to the operation of a motor vehicle while intoxicated by alcohol or a drug, while impaired by alcohol or a drug, or while under the influence of alcohol or a drug; (2) The cancellation, suspension, or revocation of a license to operate a motor vehicle after November 29, 1990, for a cause related to the operation of a motor vehicle while intoxicated by alcohol or a drug, while impaired by alcohol or a drug, or while under the influence of alcohol or a drug; (3) The denial after November 29, 1990, of an application for a license to operate a motor vehicle for a cause related to the operation of a motor vehicle while intoxicated b alcohol or a drug, while impaired by alcohol or a drug, or while under the influence of alcohol or a drug. Mr. Daniels was not involved with a motor vehicle; therefore, he does not fall under any of these definitions of a motor vehicle action. This means that Mr. Daniels will not have to report to the FAA.