To detail the warmth structure of MgO (Magnesium Oxide) using Hess’s Law, which states the warmth among a chemical reaction is stubborn of the track between the moderate and decisive states.
Chemical reactions demand warmth ardor to adequate, denominated an endothermic reaction, or product warmth ardor, and thus denominated an exothermic reaction. The warmth ardor productd by such reactions can be meted using a calorimeter, a ingredient of equipment that can separate the reaction in an insulated container. Using the calorimeter one can then detail the melt and descend in region of the reaction. When this region vary is multigenous by the warmth accommodation, the completionity of warmth needed to instruct the region of a assemblage by one mete, we can mete the vary in converting our moderate components (reactants) to their relative products.
In this trial we achieve mete the completionity of warmth released from 3 reactions (ΔHA ΔHB ΔHC) and apportion the sum of all 3 reactions to detail ΔHT, which achieve yield us the warmth structure of MgO. If Hess’s law holds gentleman and omitting minimal trialal blunder, the track we use to detail ΔHT should feel no behavior on our estimation matching the reliefficient estimation of MgO.
As per lab manual we used a calibrated calorimeter (using a rounded end thermometer so as to not poke a retreat in the calorimeter) to detail the warmths of reaction for Magnesium (Mg) delay Hydrochloric Acid (HCl) and Hydrochloric Acid delay Magnesium Oxide (MgO). Then using matter-of-fact formulas we were efficient to apportion the warmth structure of MgO, which is meted in kJ/Mol. Since twain reactions are in paralyze steep solutions of HCl it was compulsory to comprehend the warmth accommodation of steep, but consequently some warmth would be communicated to the calorimeter whose warmth accommodation was obscure, we had to proceedings a discipline ingredient (x) naturalized upon the inequitefficient warmth of steep using the equation [m(h2o)+X]Cwater+Δwater=-1(m(ice steep)CwaterΔtice steep).
We then proceedingsed the lump (m) of compass region steep and ice steep each in a relative cup and then poured the ice steep into the compass region steep and proceedingsed the region vary. By comprehending (x) we could then apportion the warmth of reaction for Mg delay HCl (ΔHA kJ/mol) and for HCl delay MgO (ΔHB kJ/mol) using the equation q=m(HCl+X)C ΔT where m is the lump of the reactant used delay Mg + X, C is the warmth accommodation of steep (4.184 J/g°C), and ΔT is the completion region vary in each reaction. Using the results of these estimations and Hess’s law we can then detail the warmth structure for MgO.
All lump readings are yieldn in units of grams (g), and all region readings are yieldn in metes Celsius (°C).
Mass of the Calorimeter + Room
Temp Steep (g)48.08
Mass of compass temp steep (g)46.29
Mass of Cal + compass temp steep + ice
Mass of ice steep (g)67.32
Temp of compass temp steep (°C)42.4
Temp of the ice steep (°C)0.1
Final temp. of compass temp steep (°C)17.3
Change in temp of ice steep (°C)17.2
Change of temp of compass temp steep (°C)-25.1
Mass of the calorimeter (g)1.79
Mass of Calorimeter (g)1.79
Mass of Cal + HCl (g)103.55
Mass of HCL (g)101.76
Mass of Mg (g)0.5
Temperature of HCl (°C)20.3
Final region of HCl + Mg (°C)42.0
Change in Region (°C)21.7
Mass of Calorimeter (g)1.79
Mass of Cal + HCl (g)101.76
Mass of HCl (g)99.88
Mass of MgO (g)0.8
Temperature of HCl (°C)20.3
Final region of HCl + MgO (°C)25.8
Change in Region (°C)5.50
Results and Discussion
To apportion X using the equation [m(h2o)+X]Cwater+Δwater=-1(m(ice steep)CwaterΔtice steep) the variefficient X must be separated and doing so we were than efficient to apportion the discipline ingredient:
Based on the estimations of the calorimeter discipline ingredient, X was detaild to be 0.158 g. Then using the equation q=m(HCl+X)C *ΔT, where q is correspondent to the completionity of ardor yieldn off, and than careful the appraise in -kJ/Mol (consequently these are exothermic reactions) we were efficient to detail ΔHA and ΔHB.
qA=(101.76 g + 0.158 g) x 4.184 J/g°C x 21.7°C
qA= 9250 J = 9.250 kJ 9.253602176
qB= m(HCl+X)C xΔT
qB=(101.76 g + 0.158 g) x 4.184 J/g°C x 5.50°C
qB=2350 J = 2.350 kJ
To then apportion the warmth structure of MgO ΔHT, the sum of all the reactions must be detaild including ΔHC, the warmth structure of steep, which is already prerooted to be -285.8 kJ/mol. However to detail the just equation for ΔHT, the stoichiometric equations must chief be balanced:
Therefore the warmth structure of MgO was detaild to be -618.35 kJ/mol. According to the textbook, the reliefficient appraise for ΔHT=-601.8 kJ/mol. To detail the correctness of the estimation we can detail the % blunder:
As far as correctness goes a percent blunder of 2.75% is very agreeable. Consequently the methods of the trial were conducted using a undigested calorimeter I would feel foreseeed the percent blunder to be conspicuous, gorgeous that consequently of it’s fabric it would not feel very eminent competency.
I would foresee that any blunder that might feel occurred happened during the transposition from one cup to another. Consequently the substances were communicated so promptly and importation into recital the calculate of seconds that it took to substitute the thermometer to start proceedingsing basis intermittently it is potential that ardor was either past in the remove or ardor was past antecedently the proceedingsing was actually efficient to start.
In this lab we were efficient to detail the warmth of structure of MgO using a simply constrained calorimeter, which was set-up to be -618.35 kJ/mol.