
Objectives

Today I will be able to:

Calculate the heat absorbed and released in a chemical reaction

Informal assessment – monitoring student interactions and questions as they complete the practice problems

Formal assessment – analyzing student work from the practice problems and exit ticket

Common Core Connection

Make sense of problems and persevere in solving them

Reason abstractly and quantitatively


Evaluate: Warm Up

Formal assessment

Directed Practice Problems

Informal assessment

Individual Practice Problems

Informal/formal assessment

Evaluate: Exit Ticket

Formal assessment


Carbon exists in two natural forms: graphite and diamond. Each form can be combusted:




C
(graphite)
C
(diamond)
+ O
2(g)
+ O
2(g)
 CO
2(g)
 CO
2(g)
∆H = -393.5 kJ
∆H = -395.4 kJ
Calculate ∆H of the conversion of graphite to diamond: C
(graphite)
 C
(diamond)
HW: Finish Calorimetry Problems


Today I will be able to:

Calculate the heat absorbed and released in a chemical reaction


Study for Thermochemistry Quiz on
Wednesday, April 15


Warm Up

Directed Practice Problems

Individual Practice Problems

Exit Ticket


Calculate ∆H for the reaction 4 NH
3
O
2
(g)  4 NO (g) + 6 H following data.
2
(g) + 5
O (g), from the

N
2
(g) + O
2
(g)  2 NO (g) ∆H = -180.5 kJ

N
2
(g) + 3 H
2
(g)  2 NH
3
(g)∆H = -91.8 kJ

2 H
2
(g) + O
2
(g)  2 H
2
O (g) ∆H = -483.6 kJ


Example 1:

You put 103.0 g of aluminum in 100.0 grams of boiling water. The water temperature changes from 100.0ºC to 90.0ºC, while the aluminum temperature goes from 25.0ºC to 70.0ºC. What is the specific heat of aluminum?

Al H
2
O
-(103.0g)(c)(70.0-25.0
° C) (100.0g)(4.184J/g ° C)(90.0-100.0
° C)
-4640 g ° C(c) = -4180 J
c = 0.901 J/g ° C


What if something dissolves in the water?
What happens to the total mass???

You add them up! The whole solution increases (or decreases) in heat.


A chemistry student dissolves 4.51 grams of room temperature sodium hydroxide in
100.00 g of water at room temperature,
19.5
° C. As the sodium hydroxide dissolves, the temperature of the solution increases to
31.7
° C. Determine the heat of solution of the sodium hydroxide in J/mol.


47.3 kJ/mol


Calorimetry Problems

You may check Ms. Ose’s answer key as you work


Based on the calorimetry data presented below, is the reaction endothermic or exothermic? Explain.