CHEM 1021 Lecture Notes - Lecture 30: Ethylene Glycol, Heat Capacity, Joule
Document Summary
Chemistry 1021 q=mc t q represents heat m represents mass. Example: find the heat transferred in kj when 550. ml of ethylene glycol (density = 1. 1 g/ml, c = 2. 42. J/gc) cools from 37. 0 c to 25. 0 c. q = (550. 0 ml)(1. 11 g/ml)(2. 42j/gc)(25. 0c-37. 0c) = -17728. 92 j. Divide by 1000 to change to kj = -17. 7 kj. Clicker1: suppose 25. 0 g of aluminum is initially at 300. 2. 35 x 10^3 j = (25. 0 g)(0. 900 j/gk) t (solve for t) Heat transfer and calorimetry: general equation uses the law of conservation of energy! O = sum of all heats in the problems. Coffee-cup calorimeter = constant pressure: measure heat capacity or specific heat capacity, measure heats of reaction if the reaction occurs in solution, measure heats of solution. Coffee-cup calorimeter assumptions: the specific heat capacity for the calorimeter is equal to that of the water, the density of water is 1. 00 g/ml, no heat is transferred between the calorimeter and the room.
