Name Period Date S T A T I O N 1 E X O T H E R M I C / E N D O T H E R M I C P R O C E S S E S Determine if each statement describes an exothermic process (EXO) or endothermic process (ENDO). surroundings get warmer PE diagram is uphill combustion of propanol H is positive reactants have more energy than products CaCO 3(s) + heat CaO(s) + CO 2(g) q < 0 H is negative q > 0 molecular attractions strengthen surroundings get colder H 2(g) + ½O 2 (g) H 2O (l) + heat products have more energy than reactants condensation of water H 2O (l) H 2O (g) water, when placed in the freezer S T A T I O N 2 H r x n C A L C U L A T I O N S Consider the following balanced equation for the combustion of propane, C 3H 8. Use the Chart of Thermodynamic Values for H f and bond energies. C 3H 8 (g) + 5 O 2 (g) 3 CO 2 (g) + 4 H 2O (l) Products Reactants Method Fill in the values of H f for each substance. Compound C 3H 8 (g) O 2 (g) CO 2 (g) H 2O (l) Hf (/mol) Bond Energy Method Given the following structural formulas. Substance Structures Calculate the H rxn using the H f values. Calculate the H rxn using bond energies. C 3H 8 O 2 CO 2 H 2O H O H The two answers above do not match. Which one is more accurate? Why?
S T A T I O N 3 C A L O R I M E T R Y A 100. g aluminum block (C = 0.900 /g ºC) in boiling water is added to an insulated cup containing 50.0 grams of water (C = 4.184 /g ºC) at 5.00ºC. Calculate the final temperature of the mixture S T A T I O N 4 E N E R G Y F L O W Heat always flows from an object of temperature to an object of temperature. Both blocks have a temperature of 22.5 C. Use arrows on the top picture to show the flow of heat and why the ice acts the way it does. Provide a brief explanation for the observed differences. Time Block A Block B Explanation 0 minutes 2 minutes
S T A T I O N 5 H E A T S O F F U S I O N & V APO R I Z A T I O N mol, Hvap = 40.68 mol, Cice = 2.10 What is the value of q when 45.0 g of water freezes at 0 C? What mass of water can be vaporized with 75.0 of energy? S T A T I O N 6 H r x n F R O M D A T A Write the balanced thermochemical equation for the combustion of pentane, C 5H 12. When 10.0 g of C 5H 12 is burned, 453 of energy is released. What is the H rxn for the combustion of pentane? Write the balanced thermochemical equation for the melting of aluminum. (Include states.) When 10.0 grams of aluminum melts, 3.929 of energy is required. What is the H fus of Al?
S T A T I O N 7 C O M P A R I N G S U B S T A N C E S Blocks X and Z have the same mass. When 500 of heat is added to each, the temperature of Block X rises 10 ºC while the temperature of Block Z rises 30 ºC. Which block has the larger specific heat, C? ustify your answer without math. 0.15 mole samples of Liquid A and Liquid B were kept at their boiling points. When 400 of energy is added to each, Liquid A completely vaporizes while some of Liquid B remained. Which liquid has a greater H vap? ustify your answer without math. S T A T I O N 8 H E A T I N G C U R V E Sketch the graph when 40.0 g of ice at 30 C is heated to steam at 140 C. Label the axes (with units), and the Freezing and Boiling points. Label the segments (a) through (e). Identify the state(s) of matter for each segment. In which segments: (circle) are molecular attractions weakening? a b c d e is the kinetic energy increasing? a b c d e are the processes endothermic? a b c d e are the processes exothermic? a b c d e do you use q = m C T to calculate the heat? a b c d e do you use q = n H to calculate the heat? a b c d e
S T A T I O N 9 H E A T I N G C U R V E C A L C U L A T I O N S, Hvap = 40.68, Cice = 2.10 mol mol A 50.0 gram sample of ice at 0.0 ºC is heated until it is liquid at 80.0 ºC. Indicate on the heating curve where the heating process begins and ends. Calculate the heat absorbed by this process. S T A T I O N 9 H E A T I N G C U R V E C A L C U L A T I O N S, Hvap = 40.68, Cice = 2.10 mol mol A 50.0 gram sample of ice at 0.0 ºC is heated until it is liquid at 80.0 ºC. Indicate on the heating curve where the heating process begins and ends. Calculate the heat absorbed by this process.