1. As always… Lon-Capa assignments Lecture videos Textbook Read
Do text homework

2. Office Hours 3014 Chemistry Annex decoste@illinois.edu
11am-12pm Mondays and Wednesdays (after lecture)
10-11 am Tuesdays and 1-2 pm Thursdays
By appointment; open-door policy

3. Clicker Question
Calculate E for a system that releases 28 J of heat while 63 J of work is done on it.
a) -35 J
b) -91 J
c) 35 J
d) 91 J

4. Clicker Question Use the following data for methanol (CH3OH):
ΔHvaporization = 35.3 kJ/mol at 64.7°C
Determine ΔE (kJ/mol) for methanol vaporizing at 64.7°C.
a) b) c) –35.3 d) e) –38.1

5. Determining Hrxn
Since H = qp, determine the heat given off or required at constant pressure by measuring temperatures. This is termed calorimetry.
Since energy is conserved, we can often determine Hrxn for one reaction given values of Hrxn for others. Uses the principle in Hess’s Law.
Use standard enthalpies of formations for reactants and products (we have tables of these).

6. A Coffee-Cup Calorimeter Made of Two Styrofoam Cups

7. Clicker Question
A 25.0 g sample of copper (c= J/gC) is placed in a boiling water bath until the temperature of the metal is 100.0C. The metal is quickly transferred to g of water at 25.0C in a calorimeter (specific heat capacity of water = 4.18 J/gC). Determine the final temperature of the water in the calorimeter.
a) 22.2°C
b) 23.2°C
c) 25.9°C
d) 26.7°C
e) 27.8°C