Calorimetry and Hess’s Law Purpose

The view of this lab is to individualize the enthalpy of reaction for the burning of one respect of magnesium in oxygen. Although the reaction is exothermic, the ∆HRXN conquer be individualized by using calorimetry and then using Hess’s Law to discuss the axioms composed to let-go the acceptance needed. Part A Volume of frigid introduce 49. 9 mL Temperature of frigid introduce (in a cup) 23. 50 C Volume of hot introduce 49. 9 mL Temperature of hot introduce (in a cup) 550 C Calculations Mass of frigid introduce 49. 9 g Tf from the graph by extrapolation 34. 90 C ∆THW for hot introduce -20. 1 ∆TCW for frigid introduce 11. 4 qHW for hot introduce -4196. 5 J qcw for frigid introduce 2380. 1 J qCal for the cup 1816. 4 J Ccup for the cup 159. 3 J Part B Description of sample Metal fizzed when dissolved in HCl Volume of HCl 100 mL Initial Temperature 220 C Mass of Mg 0. 1485 g Calculations Tf from graph 50 C Mass of HCl 100 g ∆TCW for HCl -2092 J qHCl for key -204. 4 J qCal for cup -2296. 4 J qRXN -47594 J ∆HRXN for Mg - NET REACTION: 2HCl(aq) + Mg(s)>MgCl2(aq) + H2(g) Part C Description of sample - Volume of HCl 100 mL Temperature of HCl 220 C Mass of MgO 0. 5052 g Calculations Tf from graph 240 C ∆TCW for HCl 1. 50 C qHCl for HCl 627. 6 J qCal for cup 61. 32 J qRXN 608. 92 J ∆HRXN for Mgo 55469 J/mol Net Equation: 2HCl(aq) + MgO(s)>MgCl2(aq) + H2O(l) Conclusion In this exemplification, we had to experience the fever talents of the calorimeter cup using two trials of hot and frigid introduce. When we obtained the axioms succeeding 10 minutes of recording 30-second intervals of the calorimeter cup latitude, we created a outoutsequence graph to demonstration the bear outline. Read this chemistry exercise examination. With the bear outline, we could likeness out the decisive latitude and delta H in the way. Delay the equation we could experience the fever of reaction for hot introduce q HW = m c DTHW and using qCW = m c DTCW we could experience the fever of reaction for frigid introduce. By using |qHW| = |qCW |+ qCal, we can experience the fever of reaction of the cup and unfold that by the substitute in latitude to experience the fever talents. Succeeding placing Mg into HCl and then the similar subject delay MgO, we could experience the fever of key of HCl delay q CW = m c DTHCl. When we institute the estimates of DHRXN for B and C we can use Hess's Law, which is demonstrationn in the calculations minority. All the axioms is in the axioms minority of the rumor. The percent blunder of Mg was environing 30%. The explicit estimate of Mg was 601200 J/mol and the exemplification we obtained was 420611 J/mol. There could own been ethnical blunder in appoint to obtain the results that could own accounted for the 30% blunder, although this is not so violent. Also, the fever of structure we used was MgO(s) for the explicit estimate, although in the exemplification it was a gas. This could own so accounted for some blunders. References: “ Calorimetry and Hess’s Law. ” Laboratory Manual. Publishing, 2012, pp. 168-177.