Chemistry Week 29 Please get out your notebooks and homework!

April 2, 2012 AGENDA: 1 – Bell Ringer & Agenda 2 – Review HW 3 – CN: Heat Curves and Heat Capacity 4 – Work Time: Heat Curves and Heat Capacity Today’s Goal: Students will be able to interpret heat curves and calculate heat. Homework 1. Heat Curves and Heat Transfer 2. Binder Check!

Tuesday, April 2 nd Objective: Students will be able to interpret heat curves and calculate heat. Bell Ringer: If the temperature of the surrounding decreases, is this process endothermic or exothermic. Explain using the terms heat, surrounding and system.

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Tuesday, April 2 nd Objective: Students will be able to interpret heat curves and calculate heat. Bell Ringer: If the temperature of the surrounding decreases, is this process endothermic or exothermic. Explain using the terms heat, surrounding and system.

April 2, 2012 AGENDA: 1 – Bell Ringer & Agenda 2 – Review HW 3 – CN: Heat Curves and Heat Capacity 4 – Work Time: Heat Curves and Heat Capacity Today’s Goal: Students will be able to interpret heat curves and calculate heat. Homework 1. Heat Curves and Heat Capacity 2. Binder Check!

Cornell Notes  Topic: Heat Curves and Heat Capacity  Date: 4/2/2013  Measuring energy: Universe = Surroundings + System SurroundingsSurroundings System HeatHeat EndothermicExothermic Review from yesterday q =(-) q =(+) q = q of the surrounding

Cornell Notes Heat Curve = shows how temperature of the surroundings are changing during a chemical reaction. Diagram Heat Curves. Temp. of surroundings will increase. Temp. of surroundings will decrease.

Cornell Notes  Heat Capacity = the heat needed to increase the temperature of an object exactly 1°C.  The heat capacity of a substance depends on both its mass and its chemical composition.  Specific Heat (C P ) = specific to a particular compound; it is the amount of heat required to raise 1 gram of that compound 1°C.  Units = J/g ·° C  C p = q = heat (J)_________ m x ∆T mass (g) x change in temp (∆ T) Describe heat capacity. Describe specific heat.

Cornell Notes How can you calculate the heat required to change the temperature of an object?  Heat Capacity = the amount of heat required to change the temperature of an object (based upon the object’s specific heat.) q = m · C p · ∆T q = heat m = mass of the substance C p = specific heat of the substance ∆T = change in temperature of object ∆T = T final – T initial

Cornell Notes Example #1 If the specific heat of water is 4.18 J/g°C, what is the heat used if 4.5 grams of water is raised from a temperature of 15°C to 75 °C. q = m · C p · ∆T m = 4.5 g C P = 4.18 J/g°C ∆T = 75 °C – 15 °C = 60 °C q = ( 4.5 g) (4.18 J/g°C) (60°C) q = J or kJ q = x

Cornell Notes Example #2 If the specific heat of water is 4.18 J/g°C, what is the mass of the water if J of heat was used when the temperature was changed from 85°C to 20 °C. q = m · C p · ∆T q = J C P = 4.18 J/g°C ∆T = 20 °C – 85 °C = - 65 °C J= (x) (4.18 J/g°C) (- 65°C) m = 16.6 g m = x