Tue 4/16 Do WS 9.3 Do WS 9.4 (demo log) Do WS 9.5 (revie w sheet) Do Write-Up For "Mass Using Calorimetry" Lab

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1 Daily Assignment Sheet '19 NAME Period (check them off as you complete them) Due Date Assignment Wed 4/10 Do WS 9.1 Thur 4/11 Do WS 9.2 #1-6 Read Calorimetry Lab (in packet) Fri 4/12 Do WS 9.2 #7-9 Mon 4/15 (mustard day) Do Calorimetry Lab?'s Packet 9: Energy & Matter Tue 4/16 Do WS 9.3 Do WS 9.4 (demo log) Do WS 9.5 (revie w sheet) Do Write-Up For "Mass Using Calorimetry" Lab Quiz Today Come to class with packets ready to be turned in at beginning of class, with the above assignments in order, in your folder, with this page as the cover page. For 1/2 point, turn in your packet inside of a pocket-style folder. Do not use a 3-ring binder For 1 point, be sure not to turn in material from previous packets... only turn in what's listed below (see "packet order") For 1/2 point, be sure your name is on the top of this assignment sheet. packet order: - assignment sheet - WS 9.1 ~ 9.5 (don't turn in other worksheets) Some things to think about... How is it possible to add heat to something without changing its temperature? Could a substance exist that has a negative specific heat?

2 WS TYPES OF ENERGY You are driving on a rainy night with the music on! Starting with the gasoline in your tank, use the flow chart below to trace the types of energy involved in each process, then fill in the blanks. The seven choices are listed on the left, each choice is used at least once on this worksheet. The # in ( ) indicates the # of times the choice is used. Chemical NRG (used 4 times) Electrical NRG (2) Mechanical NRG (6) Nuclear NRG (1) Radiant NRG (2) Sound NRG (2) Thermal NRG (2) Gasoline in tank Combustion in engine's cylinders Pressure pushes pistons up and down Pistons spin drive shaft, turns wheels and causes car to move Pistons turn generator Electrons in generator flow through wire coils Air vibrates around engine Reaction in battery is reversed (battery recharges) Radio speakers pulse back and forth Electrons flow in battery cables Air in car vibrates to a recognizable tune Headlights glow Windshield wipers wipe Resistance causes rear defroster wire to heat up Now lets consider the steps that lead up to the gasoline in your tank: On the sun, the nuclei of H-atoms fuse together The sun shines down on the Earth Prehistoric forests grow Forests are buried and decay into a black sludge we today call crude oil 500 million years ago... Oil wells bring oil to surface; oil refines to make gasoline for your car

3 WS 9.2 Specific Heat Show all work neatly... q = m c T 1. How much heat is required to raise the temp of 654 g of water from 34.5 C to 89.7 C? Ans 2. How much heat is required to raise the temp of 654 g of silver from 34.5 C to 89.7 C? Ans 3. If 7350 J were added to 152 g of ethanol, its temp would go up by how much? Specific Heats substance c (J/g C) water ethanol graphite diamond iron copper silver gold ice g of water at 54.0 C releases J. What will be its final temp? hint: it's cooling down, so the final temperature will be less than 54.0 C J are added to a 36.8 g of kerosene and the temp increases from 22.5 C to 34.7 C. Determine kerosene's specific heat copper pennies (each weighing 3.12 g) are placed in 36.0 g of ethanol at room temp (22.1 C). How much heat will it take to raise the temperature up to 65.8 C? hint: Calculate q for the copper & q for the ethanol separately. Then add your 2 answers together 7. What mass of 54.0 C water must be added to 468 g of 21.0 C water to make the final temp of both come out to be 29.0 C? 8. What mass of 54.0 C gold must be added to 468 g of 21.0 C water to make the final temp of both come out to be 29.0 C? 9. A 325 g brass rod at C is placed in a cup containing 162 g of 24.3 C water. The final temp comes out to be 37.4 C. Determine brass's specific heat. x1. BONUS: g of water at 20.0 C are mixed with g of copper at 40.0 C. What will the final temp come out to be? Ans 1-9 (IRO+1): ,000 units (IRO+1): J J J C C C g g J/g C J/g C

4 WS Thermodynamics Concepts & Vocab Specific Heat Specific heat is a property which is a measurement of the amount of energy (in calories or joules) required to raise one of a substance by 1 C. Some materials, such as copper, have a specific heat. This means that it doesnʼt require much heat for that material to change its. In fact, this is why copper is often used in - it heats up quickly & heat to the food quickly. Other materials, such as, have a high specific. This means that they resist in temperature. A whopping 2.1 joules of heat are to warm 1 gram of by 1 C, making it an ideal material for protecting the during reentry. Water has a high specific heat: 4.2 This is why water takes so long to undergo changes. Ever wonder how can stay cool in the?...why lakes take so long to in the? Itʼs all due to waterʼs ability to changes in temperature. Answers, in alphabetical order + 1 extra (IAO +) ** cross them off as you go! ** ceramic, ceramic, changes, cookware, freeze, gram, heat, J/g C, low, phase, physical, required, resist, space shuttle, sugar, summer, swimming pools, temperature, temperature, thermal, transfers, very, winter Calorimetry In the lab, you were able to calculate the specific heat of by heating it in a test tube, mixing it with cool, and measuring the change. The aluminum had a large temperature change (partly due to its specific heat) and the water had a temperature change (partly due to its high specific heat). According to the 1st Law of, which states that energy is, the heat lost by the aluminum was to the heat gained by the water. This is a valid assumption, since we did the mixing in a well-insulated cup. Remember, a calorimeter measures heat... not to be confused with a thermometer, which measures. Answers, in alphabetical order + 1 extra (IAO +) ** cross them off as you go! ** aluminum, calorimetry, chemistry, conserved, equal, low, small, styrofoam, temp., temp., thermodynamics, water

5 WS Demo Log - Thermodynamics Shuttle Tile (* these demos are on objective sheet) Paper Plate Liquid Nitrogen + Water Warm Touch/Cool Touch Blocks Super Cold Condensation What liquid is condensing off the can? Superheated Steam How cold is this liquid? How cold is the can? Name 1 chemical property of this liquid: Name 2 physical properties of this liquid:

6 WS 9.5 REVIEW 1. Define the following as sound, thermal, radiant, chemical, or mechanical energy: a) light from a wood fire b) heat from a wood fire c) wood d) saw cutting the wood e) crackle of the fire 2. How much heat (in joules) is required to raise the temp of 205 g of water from 15.2 C to 16.2 C? Ans 3. What mass of 67.5 C iron must be added to 235 g of 5.00 C water to make the final temp of both come out to be 15.0 C? Specific Heats substance c (J/g C) water iron Ans 4.5 Use the following calorimeter data to determine the specific heat of the unknown material: mass of unknown: g temp of unknown: 78.5 C mass of water: g initial temp of water: 22.0 C final temp of water: 26.4 C specific heat of unknown = --- Please Check Solutions Page On Class Website ---

7 Calorimetry Lab (side 1) Name A calorimeter is a device used to measure heat flow. It is a container with insulating walls, made so that essentially no heat is exchanged between the contents of the calorimeter and the surroundings. The purpose of this experiment is to determine the specific heat (c) of aluminum. This will be accomplished by heating the aluminum to a certain temperature, adding the aluminum to the water inside the calorimeter, and measuring the rise in water temperature. Procedure 1. Record the mass of about 15 aluminum pellets. Insert pellets into a large test tube, and place test tube in hot water bath. Heat for about 5 minutes. While it's warming up Add (and weigh) about 50 ml of water in the calorimeter cup. Record mass of water in data table. thermometer Styrofoam lid 3. After about 5 minutes have passed, use the thermometer to measure & record the initial temp. of the aluminum in the test tube. 4. Move thermometer to the calorimeter, making sure the tip is submerged in the water. Record the initial temp. of the water. water Styrofoam cup 5. Take the test tube out of the hot water, and pour the metal into the calorimeter. Replace the calorimeter lid and agitate the water by swirling continuously. 6. Record the temperature of the water. approx every 30 seconds. Your final temperature will be the maximum temperature reached. mass of aluminum temp of aluminum mass water Trial 1 Trial 2 initial T final T = maximum temp. reached time water temperature, C (min) Trial 1 Trial Calculations 1. Using the equation m c T = m c T, calculate c for the aluminum for trial 1 and then again for trial 2. (Use J/g C for the specific heat of water). For 1/2 point, don't forget units!! Ans (trial 1) Ans (trial 2) 2. What is the actual value for the specific heat of aluminum, printed on the back-side of your periodic table? J/g C

8 Questions: ( calorimetry lab, side 2 ) 1. Calculate the average specific heat for aluminum, based on trial #1 & trial #2: 2. Calculate your % error, based on this average & the actual value from the periodic table: % error = (actual value - experimental average) actual value. Then multiply by Which component (the aluminum or water) experienced a greater change in temperature ( T)? 4. Give two possible explanations for your observations in question #3: 5. Consider each of the following potential error sources: Answer:.. Thinker question! STOP and CONSIDER how these errors would affect your calculation for specific heat..."h" if it would have caused your experimental value for aluminum to come out too high,..."l" if it would have caused it to come out too low, or..."n" if it would have had no effect at all on your value You forgot to subtract the mass of the empty calorimeter cup After weighing the aluminum pellets, a few of them unknowingly fell to the floor You measured the temperature using the Kelvin scale You used a metal can (which conducts heat away) instead of styrofoam (which insulates) You unknowingly used ethanol (specific heat = J/g C) instead of water Someone drank some of your calorimeter water after you weighed it Instead of using water you used ethanol, and used ethanol's specific heat in the equation Answer Bank (prob #5): IRO: L L N N H H H