CHY 102 Lecture Notes - Lecture 23: Calorimetry, Sodium Hydroxide, Thermometer
Document Summary
Constant v calorimetry yielded ru recall: ru = qv. Constant p calorimetry yields rh recall: rh = qp. Measure temp changes for aqueous reactions & calculate heat. 50. 0 ml of 1. 00 m hcl are added to 50. 0 ml of 1. 00 m naoh in a calorimeter. Cs,h20 = 4. 184 j g-1 k-1, h2o = 1. 00 g/ml. T = (27. 5-21. 0) c = 6. 5 c = 6. 5 k mh2o = h2ovh2o = (1. 00 g/ml)(100 ml) = 100 g. Hrxn = -(100 g)(4. 18 j/g/k)(6. 5 k) = -2. 7 kj. Moles hcl = (50. 0 10-3 l) (1. 00 mol/l) = 50. 0 10-3 mol. Hrxn = (-2. 7 kj)/(50 10-3 mol) = -54 kj/mol. If a reaction is carried out in a series of steps, rh is the sum of all the rh"s of the individual steps. Consequence of h being a state function. Tabulated rh can be used to calculate the rh of a reaction that does not appear in the table.
