1. Heat Calculations Agenda Discuss Lab Notes on Heat Calculations Homework

2. Lab Intro: unknown or building or … M&M: –don’t list supplies, –construction of cal Results: Charts –Data used for calculations –Temperature over time Conclusions: –What does it all mean? –Talk about data!!! –Do NOT tell me hypothesis was correct/right!

3. KnownUnknown Mass of metal Mass of cal&H 2 O Mass of cal Mass of H 2 O T I metal (Boiling H 2 O) T I water/cal T F system  T metal  T cal q water s metal

4. Heat Calculations Date:

5. Time TEMPERATURETEMPERATURE

6. TEMPERATURETEMPERATURE SOLID LIQUID GAS FREEZE MELT CONDENSE VAPORIZE 0OC0OC 100 O C

7. Time TEMPERATURETEMPERATURE SOLID LIQUID GAS FREEZE MELT CONDENSE VAPORIZE 0OC0OC 100 O C ENDOTHERMIC  EXOTHERMIC 

8. Time TEMPERATURETEMPERATURE SOLID LIQUID GAS FREEZE MELT CONDENSE VAPORIZE 0OC0OC 100 O C ENDOTHERMIC  EXOTHERMIC  q = m*s*  T s ice = 0.5cal/g o C q = m*s*  T s liquid = 1cal/g o C q = m*s*  T S gas = 0.4cal/g o C q = m*  H fusion  H fusion = 80 cal/g q = m*  H vap  H vap = 540cal/g

9. Solving Problems Read question and determine number of “lines” involved. Calculate the amount of heat required for each “line” Determine the sum of all “lines” used. IF ENERGY IS RELEASED, you MUST make  H fus and  H vap negative!!!!

10. Calculate the amount of heat necessary to raise 20g H 2 O from -10 o C to 45 o C Determine lines: -10 o C = solid, 45 o C = liquid so 3 lines used. Solid: q = m*s ice *  T q = (20g)(0.5cal/g o C)(0 o C – (-10 o C)) = Melt: q = m*  H fus q = (20g)(80cal/g) = Liquid: q = m*s liquid *  T q = (20g)(1cal/g o C)(45 o C – 0 o C) = TOTAL AMOUNT OF HEAT =

11. Calculate the amount of heat released when 30g H 2 O are cooled from 115 o C to 65 o C Determine lines: 65 o C = liquid, 115 o C = gas so 3 lines used. Gas: q = m*s gas *  T q = (30g)(0.4cal/g o C)(100 o C – 115 o C) = Condensed: q = m*  H fus q = (30g)(-540cal/g) = Liquid: q = m*s liquid *  T q = (30g)(1cal/g o C)(65 o C – 100 o C) = TOTAL AMOUNT OF RELEASED HEAT =

12. Suppose the heat needed to melt 38.0g of ice is absorbed from water contained in a glass. If this water has a mass of 210. g and an initial temperature of 21.0 o C, what is the final temperature of the water? Remember the ice melts and then warms up as a liquid.