Chemistry: The Central Science (13th Edition)

Published by Prentice Hall
ISBN 10: 0321910419
ISBN 13: 978-0-32191-041-7

Chapter 5 - Thermochemistry - Exercises - Page 206: 5.55b


-44.42 kJ/mol

Work Step by Step

In part a we found that the NaOH dissolving releases 7.219 kJ of heat. We need to find the molar mass of 6.5g of NaOH. Na is 22.99 g/mol O is 16 g/mol H is 1 g/mol NaOH is 39.99 g/mol Therefore, 6.5 g is : (6.5g) * (1mol/39.99g) = 0.1625 mol Since 7.219kJ was released, that makes it exothermic and turns 7.219kJ to -7.219kJ. Then we divide the the heat released by the molar mass to find the kJ/mol : (-7.219kJ) / (0.1625mol) = -44.42 kJ/mol
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