University:
College
Course:
College Computer Science
Academic year:

2024
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375

Pages:

23
Author:

Mariya H.

Unit 18A Mariya Hussain (Group 3) 27th October 2023 10632164 Assignment 18A Demonstrate accurate measurement of enthalpy changes and assess the quality of the results. Name of experiment 1: Measurement of enthalpy changes- Solution of anhydrous sodium carbonate Introduction: Calorimetry is the process by which heat is transferred in a chemical or physical process this can be measured using a calorimeter (Clark 2010). Diagram below is a basic calorimeter set up, styrofoam cup system is dissolved in the water The enthalpy change of solution is known as, the enthalpy change when 1 mole of an ionic substance dissolves in water to give a solution of infinite dilution (Clark 2010). Heat transferred by a reaction can be used to determine the change in enthalpy of a reaction (Clark 2010). In endothermic reactions, energy enters from the surroundings and in exothermic reactions, energy exits to the surroundings (Clark 2010). Aim: To determine the enthalpy change in kJ/mol for anhydrous sodium carbonate by dissolving into water. Hypothesis: Anhydrous sodium carbonate dissolved in water is an exothermic reaction Prediction: When anhydrous sodium carbonate dissolved in water the temperature of the water will increase Risk assessment: Hazards Risks Personal protective equipment (PPE) Precautions Anhydrous sodium carbonate Eye irritation Skin irritathion Wear suitable cloth Gloves, lab coat goggles Avoid Contact with eyes, Skin & Clothing Glass wear-broken glass Harmful if inhaled Cut-resistant gloves lab coat wash hands after hardling Don't handle with bare honds use cut-to resistant glovel handle Spillage of water Deep Cuts & lacerat -ons Puncture wound. goggles clean up after spillage. Slips, trips & Falls. Gloves, labcoat or apren Make sure it's dried Assignment 18A Demonstrate accurate measurement of enthalpy changes and assess the quality of the results. Variables: Independent Variable: Temperature Dependent Variable: Temperature . Control Variable: Same amount of water and same amount of anhydrous sodium carbonate Apparatus: Polystryrene cup 5g amount of anhydrous sodium carbonate 50ml amount of water Thermometer Measuring cylinder Weighing scale Weighing boat Stirring rod Stopwatch Material: • Anhydrous Sodium carbonate Method: 1. Weigh out 5g of anhydrous sodium carbonate using the weighing boat 2. Measure 50ml of water using the measuring cylinder and pour into the polystyrene cup. 3. Record the initial temperature of the water 4. Add the 5g of anhydrous sodium carbonate into the polystyrene cup and measure the temperature change, whilst stirring the mixture every 30 seconds. 5. Thoroughly clean out and dry the calorimeter and repeat the test. 6. Repeat the above process and collate the results in an appropriate table. Exp4 Calculations Repeat 1: Q=MCAT Q=B0x4.18 x 4 = 886836J C= 4.18 n = Mass Mr =5.09 106 △H=836 M= 50g. = 0.05 moles. 0.05 AT=4°C =16,720701 Repeat 2: Q=MCAT Q=50x4.18 x 43 = 898.75 H=2=898.7 A 0.04 M=509 n. mass = 435=0.04molel 106 Mr C=4.18 At = 4.3°C =22467.5 Assignment 18A Demonstrate accurate measurement of enthalpy changes and assess the quality the results. Results Measurements taken: Mass (g): Repeat 1: Empty weighing boat: 1.07 Repeat 2: 1.05 Average: 1.06 Weighing boat with anhydrous sodium carbonate: 6.07 5.02 5.01 Anhydrous Sodium Carbonate final mass: 5.00 4.50 5.06 Beaker filled with Water mass: 50 50 50 1cm³ = 1 gram Analogue Temp Temperature taken: Temperature (°C) Repeat 1: Repeat 2: Average: Initial temperature of the beaker and water: 23 22.9 22.95 Final temperature of the Beaker (water + Sodium 27 27.2 271 carbonate): Temperature Change: 4 4-3 Digital thermometer Measurements taken (°C, Seconds, g) Repeat 1: Repeat 2: Average: Initial Temperature water 22.1 22 22.0 Final temperature 26.6 26.5 26.5 Water + Na₂CO₃ Temperature change 45 4.5 4.5 Mass of empty weighing boat 1.07 1.05 1.06 Weighing boat with Na₂CO₃ 6.07 5.02 5.01 Mass of Na₂CO, 5.00 4.50 5.06 Time taken 30 30 30 Calculations Average: Q=mc AT m=50g C=418 OT=4.5°C n= mass Mr = 5.06=0.05moler. (Round to 35F). 106 Q=50x4.18x4.5 =940.55 HQ= 940.5=11,810/1 0.05 Assignment 18A Demonstrate accurate measurement of enthalpy changes and assess the quality of the results. Aim: Name of experiment 2: Measurement of enthalpy changes- Solution of ammonium chloride To determine the enthalpy change in kJ/mol for ammonium chloride by dissolving into water Hypothesis: Ammonium chloride dissolved in water is an endothermic reaction Prediction: When ammonium chloride dissolved in water the temperature of the water will decrease Risk assessment: Hazards Risks Personal protective equipment (PPE) Precautions harmful Ammonium chloride - Irritation, Possible Goggles, Gloves eve damage wear impermeable gloves, wash hands after hardiing Headache confusion Glass wear-broken glass Deep cuts & lacerations, ure wounds. Punct Cut-resistant gloves, lab focu goggless Spillage of water Variables: Slips, trips & falls. Gloves, lab Lout or apron. Independent Variable: Temperature Dependent Variable: Temperature Don 'thandie with bare hands use uut resistant gloves Cleanupafter Spillage make sure it's dried! Q=mCAT Control Variable: Same amount of water and same amount of ammonium chloride Apparatus: • Polystryrene cup . Stirring rod Exp2: Average: M=509 Sg amount of Ammonium chloride 50ml amount of water Thermometer Measuring cylinder Weighing scale Weighing boat Stopwatch Material: Ammonium chloride C=4.18 Q-50x4.18×7.5 AT=7.5°C. = 1567.5J △H=Q=1567.5=16854.8 0.093 (1dp) n=mass Mr 4.985 = 0.093mol 6535mol (3SF) KJmal -1 Assignment 18A Demonstrate accurate measurement of enthalpy changes and assess the quality of the results. Water Method: 1. Weigh out 5g of ammonium chloride using the weighing boat and measuring scale 2. Measure 50ml of water using the measuring cylinder and pour into the polystyrene cup. 3. Record the initial temperature of the water 4. Add the 5g of ammonium chloride into the polystyrene cup and measure the temperature change, whilst stirring the mixture every 30 seconds. 5. Ensure that you record the highest temperature before the calorimeter begins to cool down. 6. Thoroughly clean out and dry the calorimeter and repeat the test. Repeat the above process and collate the results in an appropriate table. Results Measurements. Mass (g): taken: Repeat 1: Repeat 2: Empty weighing boat: 1.06 1.08 Average: 107 Weighing boat with Ammonium chloride: 6.08 6.08 6.05 Ammonium chloride mass: 4.96 S 4-98 Beaker filled with SO 50 50 water: 1cm³ = 1 gram Temperature taken: Temperature (°C) Repeat 1: 23 Repeat 2: 24 17 Average: 23.5 16 Initial of the beaker water: Q=MCAT Final of the beaker water and arnmonium chloride: Temperature Change: Calculations 15 8 R1: m=50g Q=50x4.18x8 C=4.18 = 16725 7 7.5 n=mass = 4.96 -0.093moles 53.5 Mr (Roundto3sf). △H=Q=1672=17978.5 R2: M=50g Q=50x4.18x7 C=4.18 AT=7°C =1,4635 n 0.093 Kmol n=mas) = 59 = 0.093 molel 335 (356). Mr AH = Q=14635 = 15731.2/ned 6.093mol Assignment 18A Demonstrate accurate measurement of enthalpy changes and assess the quality of the results. Aim: Name of experiment 3: Measurement of enthalpy changes - Neutralisation of hydrochloric acid with sodium hydroxide To determine the enthalpy change in kJ/mol for the neutralisation of hydrochloric acid by sodium hydroxide Hypothesis: The neutralisation of hydrochloric acid by sodium hydroxide is an exothermic reaction Prediction: When aqueous hydrochloric acid reacts with aqueous sodium hydroxide the temperature of solution will increase. Risk assessment: Hazards Risks Personal protective equipment (PPE) Precautions Hydrochloric acid Sodium hydroxide eyes. Repeated Severe burns to inhalation of can lead to lung damage. Corrosive to eyes, Skin Respiratory tract infection toeye, nose Saferygtoggles. Chemical resistant suir/labcoat gloves, Avoid Contact with Sking eyes. Avoidinhalation Lab Coat, Goug les Nitrilegloves Avoid contact with skin, eyes & clothing. Permanent Spillage of sodium hydroxide and hydrochloric acid NaOH-Corrosive NaOH-Wear lab HCI-Toxic if breathed in. NaOH-Avoid contact witmeyer, skin 2 Clothing glover, goggles, coat HCI-Labcoat Acid resistant apron. HCI-Avoid inhalation of Vapour. Variables: Independent Variable: Temperature Dependent Variable: Temperature Control Variable: Same volume and strength of HCI and NaOH to be used Apparatus: Polystyrene cup Beaker 250 ml . Pipettes 2 x 25 ml . Thermometer Materials: 50 ml 1M HCI 50 ml 1M NaOH HCl=1.0x25-25-1000=0.025mol NaOH=1×25=25=0.025mol n = cx v 1000 R1: Q= mcAT M=509 C=4.18 AT-5-1 Q=50g×4.18x5.1C =1065.95 Assignment 18A Demonstrate accurate measurement of enthalpy changes and assess the quality of the results. Method: 1. Place a clean, dry polystyrene cup inside a beaker. 2. Transfer 25.0 cm³ of 1.0 moldm hydrochloric acid using a pipette into the polystyrene cup. 3. Record the temperature of the solution. 4. Using another pipette, measure 25.0 cm³ of the sodium hydroxide solution and add into the cup containing the HCL 5. Record the maximum temperature reached of the reaction in an appropriate table. 6. Repeat the test Results Measurements taken: Volume (ml) Hydrochloric acid: Sodium hydroxide: Temperature taken: Initial temperature of HCI: Q=MCOT Initial temperature of NaOH: Repeat 1: Repeat 2: Average: 25 24 24-5 25 26 25.5 Temperature (°C) Repeat 1: Repeat 2: Average: 21 2) Γ 21.05 212 21.1 21.05 Final Temperature HCI + NaOH: 26-2 261 26.1 Temperature Change: 5-1 5 5.05 5 Calculations 5 R2: M=309 = 1,045 Q=80gx4.18x5 J C=4-18 4T=5°C Average: m=50g C=4.18 AT=5.05°C Moles of NaOH & HCl = 0.025mol 41°=Q=671,045=41,800 피하기 n=cxv=1x25 11000 = 0.025mol 0.025 G=50x4.18x5.05 = 1055-45J △H= Q = 1055.455 n 0-025 mol KJMol -1 - 42,218 -1