Chem Lab – Heat of Combustion of Magnesium

Heat of Combustion of Magnesium Background The students were tending(p) full instructions on how to experimentally determine the atomic number 1 of response (? Hrxn) for the combustion of magnesium ribbon, using Hesss Law. Data Collection reaction 1 Reaction 2 (MgO) (Mg) footrace 1 Trial 2 Trial 1 Trial 2 Volume of 1. 00 M HCl 50. 0 mL 0. 5 mL 50. 0 mL 0. 5 mL 50. mL 0. 5 mL 50. 0 mL 0. 5 mL Final temperature, t2 28. 9(C 0. 1(C 28. 8(C 0. 1(C 44. 8(C 0. 1(C 44. 4( C 0. 1(C Initial temperature, t1 22. 5(C 0. 1(C 22. 3( C 0. 1(C 21. 9(C 0. 1(C 21. 8( C 0. 1(C raft of solidity 0. 50 g 0. 01g 0. 50 g 0. 01g 0. 25 g 0. 01g 0. 25 g 0. 01g Data Processing Reaction 1 (MgO) Trial 1 Trial 2 wobble in last temperature initial temperature final temperature initial temperature temperature, (t 28. (C 22. 5(C = 6. 4(C 28. 8(C 22. 3(C = 6. 3(C uncertainty of temperature 0. 1(C + 0. 1(C = 0. 2(C dubiousness of temperature 0. 1(C + 0. 1(C = 0. 2(C Change in temperature = 6. (C 0. 2(C Change in temperature = 6. 3(C 0. 2(C Heat of HCl Mass of 1. 0 M HCl pic specific heat of HCl pic shift in Mass of 1. 0 M HCl pic specific heat of HCl pic convince in solving, q temperature temperature To find mass of 1. 0 M HCl Density of 1. M HCl pic masses To find mass of 1. 0 M HCl Density of 1. 0M HCl pic volume of 1. 0M HCl of 1. 0M HCl 1. 005 pic pic 50. 0 mL = 50. 3 g 1. 005 pic pic 50. 0 mL = 50. 3 g 50. 3 g pic . 00418 pic pic 6. 4(C = 1. 3 kJ 50. g pic . 00418 pic pic 6. 3(C = 1. 3 kJ % incredulity of Heat (0. 5mL ? 50 mL) + (0. 2(C ? 6. 4(C) % perplexity of Heat (0. 5mL ? 50 mL) + (0. 2(C ? 6. 3(C) pic 100% = 4% pic 100% = 4% dubiety of Heat 4% of 1. 3 kJ = 0. 5 kJ doubtfulness of Heat 4% of 1. kJ = 0. 5 kJ Heat of HCl = 1. 3 kJ 0. 5 kJ Heat of HCl = 1. 3 kJ 0. 5 kJ atomic number 1 revision,Enthalpy change of reaction = -heat of HCl solution Enthalpy change of r eaction = -heat of HCl solution (H Enthalpy of MgO = -1. kJ 0. 5 kJ Enthalpy of MgO = -1. 3 kJ 0. 5 kJ Moles of MgO Mass of MgO ? jettyear mass of MgO Mass of MgO ? counterspyar mass of MgO 0. 50 g MgO ? 40. 30pic = 0. 0120 mol 0. 50 g MgO ? 40. 30pic = 0. 0120 mol % unbelief of moles (0. 01g ? 0. 0g) pic 100% = 2% % Uncertainty of moles (0. 01g ? 0. 50g) pic 100% = 2% Uncertainty of moles 2% of 0. 0120 mol = 0. 0002 mol Uncertainty of moles 2% of 0. 0120 mol = 0. 0002 mol Moles of MgO = 0. 0120 mol 0. 0002 mol Moles of MgO = 0. 0120 mol 0. 0002 mol Molar atomic number 1 Enthalpy of MgO ? moles of MgO Enthalpy of MgO ? oles of MgO change, (H/mol -1. 3 kJ ? 0. 0120 mol = -110 pic -1. 3 kJ ? 0. 0120 mol = -110 pic % Uncertainty (0. 5 kJ ? 1. 3 kJ) + (0. 0002 mol ? 0. 0120 mol) % Uncertainty (0. 5 kJ ? 1. 3 kJ) + (0. 0002 mol ? 0. 120 mol) pic 100% = 40% pic 100% = 40% Uncertainty 40% of -110 pic = 40 pic Uncertainty 40% of -110 p ic = 40 pic Molar atomic number 1 change = -110 pic 40 pic Molar enthalpy change = -110 pic 40 pic total zep (molar enthalpy change of Trial 1 + molar enthalpy change of Trial 2) ? enthalpy change ( -110 pic + -110 pic ) ? 2 = -110 pic Uncertainty (40 pic + 40 pic ) ? 2 = 40 pic Average molar enthalpy change = -110 pic 40 pic Reaction 2 (Mg) Trial 1 Trial 2 Change in final temperature initial temperature final temperature initial temperature temperature, (t 44. 8(C 21. 9(C = 22. 9(C 44. 4(C 21. 8(C = 22. (C Uncertainty of temperature 0. 1(C + 0. 1(C = 0. 2(C Uncertainty of temperature 0. 1(C + 0. 1(C = 0. 2(C Change in temperature = 22. 9(C 0. 2(C Change in temperature = 22. 6(C 0. 2(C Heat of HCl Mass of 1. M HCl pic specific heat of HCl pic change in Mass of 1. 0 M HCl pic specific heat of HCl pic change in solution, q temperature temperature To find mass of 1. 0 M HCl Density of 1. 0M HCl pic volume To find m ass of 1. 0 M HCl Density of 1. 0M HCl pic volume of 1. 0M HCl of 1. M HCl 1. 005 pic pic 50. 0 mL = 50. 3 g 1. 005 pic pic 50. 0 mL = 50. 3 g 50. 3 g pic . 00418 pic pic 22. 9(C = 4. 81 kJ 50. 3 g pic . 00418 pic pic 22. 6(C = 4. 75 kJ % Uncertainty of Heat (0. 5mL ? 0 mL) + (0. 2(C ? 22. 9(C) % Uncertainty of Heat (0. 5mL ? 50 mL) + (0. 2(C ? 22. 6(C) pic 100% = 1. 9% pic 100% = 1. 9% Uncertainty of Heat 1. 9% of 4. 81 kJ = 0. 09 kJ Uncertainty of Heat 1. 9% of 4. 75 kJ = 0. 09 kJ Heat of HCl = 4. 81 kJ 0. 09 kJ Heat of HCl = 4. 75 kJ 0. 9 kJ Enthalpy change,Enthalpy change of reaction = -heat of HCl solution Enthalpy change of reaction = -heat of HCl solution (H Enthalpy of Mg = -4. 81 kJ 0. 09 kJ Enthalpy of Mg = -4. 75 kJ 0. 09 kJ Moles of Mg Mass of Mg ? molar mass of Mg Mass of Mg ? molar mass of Mg 0. 25 g ? 24. 30pic = 0. 010 mol 0. 25 g ? 24. 30pic = 0. 10 mol % Uncertainty of moles (0. 01g ? 0. 25g) pic 100% = 4% % Uncertainty of moles (0. 01g ? 0. 25g) pic 100% = 4% Uncertainty of moles 4% of 0. 0100 mol = 0. 0004 mol Uncertainty of moles 4% of 0. 0100 mol = 0. 0004 mol Moles of Mg = 0. 0100 0. 0004 mol Moles of Mg = 0. 0100 0. 0004 mol Molar enthalpy Enthalpy of Mg ? oles of Mg Enthalpy of Mg ? moles of Mg change, (H/mol -4. 81kJ ? 0. 0100 mol = -481 pic -4. 75 kJ ? 0. 0100 mol = 475pic % Uncertainty (0. 09 kJ ? 4. 81 kJ) + (0. 0004 mol ? 0. 0100 % Uncertainty (0. 09 kJ ? 4. 75 kJ) + (0. 0004 mol ? 0. 100 mol) pic 100% = 6% mol) pic 100% = 6% Uncertainty 6% of -481 pic = 29 pic Uncertainty 6% of -475 pic = 29 pic Molar enthalpy change = -481 pic 29 pic Molar enthalpy change = -475 pic 29 pic Average molar (molar enthalpy change of Trial 1 + molar enthalpy change of Trial 2) ? enthalpy change (-481 pic + -475 pic ) ? 2 = -478 pic Uncertainty (29 pic + 29 pic ) ? 2 = 29 pic Average molar enthalpy change = -478 pic 29 pic