1. Agenda 4/16/2014 Slip quiz 5 Aday Calorimetry Lab Note: Ch 15 Test – Next Tuesday, April 22 Objectives: 1. Find the amount of heat released by a potato chip. 2. Solve problems involving heat flow and temperature changes. Objectives: 1. Find the amount of heat released by a potato chip. 2. Solve problems involving heat flow and temperature changes.

2. 5 Aday - Slip quiz 1.State the Law of Conservation of Energy. 2.What is energy?

3. 5 Aday - Slip quiz 1.State the Law of Conservation of Energy. The Law of Conservation of Energy states that in any chemical reaction or physical process, energy can be converted from one form to another, but it is neither created nor destroyed. (First Law of Thermodynamics).

4. 5 Aday - Slip quiz 2. What is energy? Energy is the ability to do work or produce heat. Kinetic energy – energy of motion

5. 5 Aday - Slip quiz 2. What is energy? Energy is the ability to do work or produce heat. Kinetic energy – energy of motion Potential energy – due to position of an object

6. 5 Aday - Slip quiz 2. What is energy? Energy is the ability to do work or produce heat. Kinetic energy – energy of motion Potential energy – due to position of an object chemical potential energy – energy stored in a substance because of its composition – chemical bonds holding atoms together

7. Combustion (exothermic reaction) Heat released when a substance burns in oxygen Related to the energy (chemical potential energy) stored in the bonds of the substance Heat (q) energy in the process of flowing from a warmer object to a cooler object Temperature rises when cooler object absorbs heat (warmer object’s temperature decreases)

8. Measuring Heat Measuring temperature changes – clues to heat flow The SI unit of heat and energy is the joule (J) Amount of heat required to raise the temperature of one gram of pure water by one degree Celsius is 4.184 joules (or 1 calorie). Latin Calor = heat, warmth

9. Energy Units 1 Joule = 1 J 1kilo joule = 1kJ = 1000 J 1 calorie = 1 cal = 4.184J 1 kilocalorie = 1kcal = 1000cal 1 nutritional Calorie 1 Calorie = 1 kcal

10. ChemLab16: Calorimetry Calorimetry – heat measuring (metry) –Safety precautions?

11. ChemLab16: Calorimetry Calorimetry – heat measuring (metry) 2. Safety precautions? –Tie back hair, no dangling earphones/jewelry/ loose fitting clothing –goggles –No eating the samples!

12. ChemLab16: Calorimetry Calorimetry – heat measuring (metry) 3. Hypothesis about how the quantity of heat produced by the combustion reaction (of a potato chip) will compare to the quantity of heat absorbed by the water.

13. ChemLab16: Calorimetry Calorimetry – heat measuring (metry) 3. Hypothesis about how the quantity of heat produced by the combustion reaction (of a potato chip) will compare to the quantity of heat absorbed by the water. –The heat produced by the reaction will be more than the heat actually absorbed by the water because some of the heat produced will escape into the surroundings and not be absorbed by the water.

14. ChemLab16: Calorimetry 4. Formula for calculating the quantity of heat absorbed by the water q = c x m x ΔT Where q is heat absorbed (by water) c is the specific heat (of water) m is the mass (of the water) ΔT is the change in temperature (of the water)

15. ChemLab16: Calorimetry 4. formula for calculating the quantity of heat absorbed by the water q = c x m x ΔT Specific heat of any substance is the heat required to raise the temperature of 1g of the substance by 1 degree Celsius. Different substances have different specific heats. Specific heat for water is 4.184 J/g°C

16. ChemLab16: Calorimetry 5. Assuming the potato chip contains compounds made up of carbon and hydrogen (organic compounds) what gases will be produced in the combustion reaction?

17. ChemLab16: Calorimetry 5. Assuming the potato chip contains compounds made up of carbon and hydrogen (organic compounds) what gases will be produced in the combustion reaction? CH 4 + 2 O 2  CO 2(g) + 2 H 2 O (g)

18. ChemLab16: Calorimetry Procedure – Re-written in own words. –Any questions? 9 stations – set up (check) –Use data collection unit and fast response temperature probe – get the wire arranged so it will not get close to the flame of the burning potato chip ahead of time. –Let the burned chip cool.

19. ChemLab16: Calorimetry Data Table (Results) Mass of beaker and 50mL of water Mass of empty beaker Mass of water in beaker Mass of potato chip Highest temperature of water Initial temperature of water Change in temperature

20. ChemLab16: Calorimetry Analyze and Conclude Answer all questions using complete sentences that incorporate the question into the answer you write. Example: 1.The burning of a potato chip is an exothermic reaction. I know this because I saw a bright flame (light energy) and there was heat given off by the reaction which we used to heat water. 1 nutritional Calorie 1 Calorie = 1 kcal 1 kilocalorie = 1kcal = 1000cal 1 calorie = 1 cal = 4.184J

21. Homework Read Section 16.1 Energy Answer questions 7 – 11 in Section 16.1 Assessment (p. 495) Read Section 16.2 Heat in Chemical Reactions and Processes Describe and sketch a calorimeter and explain how it can be used to measure the amount of heat absorbed or released during a chemical or physical process. Copy the 2 diagrams at the top of page 500 (Figure 16-8) including the caption. Copy table 16-4 Explain the meaning of ΔH rxn. Why is ΔH rxn sometimes positive and sometimes negative.