Thermochemistry 6 Boon Chemistry February 7 & 8, 2013
Catalyst Make a list of as many things that you can think of that we learned in the Temperature and Thermochemistry unit. In other words, what do you think will be on today’s exam? Use your worksheets and notes as clues. • Objectives • I can demonstrate my understanding of heat transfer by scoring a 3 or 4 on the Unit 8 exam. • Agenda • Catalyst • Calculations Review • Group Study • Unit 8 Exam
Exit Slip Review • Compare your exit slip to the example exit slip answers. • On today’s exam, doing all of the following will earn full credit: • Write down the formula/equation you are using. • Plug the correct numbers into the equation. • Use units throughout your work (in the equation and in your answer). • Find the correct answer.
Multi-Step Thermochemistry Problems • Step 1: Break down the problem into “temperature change” and “phase change” steps. • Use the boiling point and melting point as a guide. • Step 2: Solve the steps separately. • Use q=mcΔT for temperature change and q = mΔHt for phase change • Step 3: Add up the answers to get the total heat transferred.
Practice 3: A 150 g piece of aluminum foil is heated from 70 °C to 700 °C. The heat of fusion of aluminum is 398 J/g. The melting point of aluminum is 660 °C. Calculate the heat transferred to the aluminum. 70°C to 660 °C Melting 660 °C 660°C to 700°C Q = (m) (c) ΔT Q = (m) ΔH Q = (m) (c) ΔT Q = (150g) (0.897J/g*C) (590C) Q = (150g) (398J/g) Q = (150g) (0.897J/g*C) (40C)
Unit 8 Exam Standards • (7a) Students know how to describe temperature and heat flow in terms of the motion of molecules (or atoms). • (7b) Students know chemical processes can either release (exothermic) or absorb (endothermic) thermal energy. • (7c) Students know energy is released when a material condenses or freezes and is absorbed when a material evaporates or melts. • (7d) Students know how to solve problems involving heat flow and temperature changes, using known values of specific heat and latent heat of phase change.
Group Study • Work in a group of 2 or 3 people. • Each student gets a ¼ sheet of paper. You get to use this on your exam. • Work together to brainstorm what materials to put on your ¼ sheet. • Use all your notes and worksheets. • You have 15 minutes.
Temperature and Thermochemistry Exam • Expectations/Instructions: • Work independently and silently. • Write on your test. • Be sure to answer every question. There are multiple choice and short answer. • The Tools: • Use your ¼ sheet. • Use your own calculator. • If you finish early: • Turn in your test and all your unit 8 worksheets, handouts, etc. • Begin the reading assignment for Unit 9: read pp. 576-585 and answer questions on pp. 585 #1-13.
Homework • Due Monday/Tuesday: read pp. 576-585 and answer questions on pp. 585 #1-13.