Pre-Lab 11A: Temperature and Heat Purpose • Hot and cold are familiar sensations. What happens when something hot comes in contact with something cold? • Think about putting some ice cubes in a drink. • Things don’t remain the same, changes occur and these changes have to do with the movement of energy from one material to the other. • This investigation will explore the difference between temperature and thermal energy, • and how the movement of thermal energy relates to the concept of heat. Key Question • How are temperature and heat related? Background Define: – Temperature – Thermal energy – Specific heat Drawing • Draw a cup of water with a cube of aluminum (Al) in the cup. Procedure READ VERY CAREFULY Section 1: Read this now. Is a hypothesis, you must use: IF …THEN …BECAUSE format Change: Do not use 0 and 50 degrees waters, just use very hot and very cold waters You must predict a temperature the water will become using equal masses of the two different temperatures of water and WHY do this NOW Section 2: Use two labeled cups (1 hot and 1 cold) and fill each with their respective liquids: The hot from the flasks under the hood, the cold from your extra cup of ice-cube water Do you need to measure/use the same amount: why/why not? You will end up combining these two liquids w/ the exact same amount: how much? What goes into the third cup? All this time you are measuring the temperature of the mixed waters on the meter mode. What does the word stabilize mean? Do NOT throw ice water away, why? Section 4: Hypothesis: Use the IF …THEN …BECAUSE format do this now. Section 5: You will first mass an aluminum cube Then heat the aluminum cube (how?) Then measure out some ice cube cold water so it has the same mass as the aluminum cube: Because the cup has mass, mass the dry cup first so you can add that to the mass the aluminum cube had on your balance (called tare weight) Last, after recording the temp of each, place hot aluminum cube in a cup with the massed super cold water Use tongs to move the hot cube into the super cold water READ CAREFULY Record the temperature when stable, but do NOT WAIT LONGER THAN ONE MINUTE!!! Section 6: c. use CPO page 254 for specific heats, remember to convert to our unit used: GRAMS!! Post Lab 11A: Temperature and Heat Purpose • Hot and cold are familiar sensations. What happens when something hot comes in contact with something cold? • Think about putting some ice cubes in a drink. • Things don’t remain the same, changes occur and these changes have to do with the movement of energy from one material to the other. • This investigation will explore the difference between temperature and thermal energy, • and how the movement of thermal energy relates to the concept of heat. Key Question • How are temperature and heat related? Background • Define: – Temperature – Thermal energy – Specific heat • Suppose you mix equal masses of water. One sample is at 0 °C and the other is at 50 °C. What do you think the final temperature of the mixture will be? Why? • Did the result of your experiment agree with your prediction (within 3 degrees)? Discuss why the temperature value may not have matched exactly your predicted value. Source of error? • How do you think your results would have been different if you had used more hot water than cold water, instead of equal masses? • Suppose you mix equal masses of cold water and hot metal. Will the final temperature follow the same pattern as the experiment you did in Part 2? Explain your answer. • Why didn’t the temperature of the water and aluminum mixture come out halfway between the temperature of the cold water and hot aluminum cube, even though you mixed equal masses? • Explain what is happening between the aluminum cube and water in terms of temperature and energy. • How much energy does it take to raise the temperature of one gram of aluminum by 1 °C compared to raising the temperature of one gram of water by 1 °C? (Look up this value.) Relate your answer back to your experimental results. E=MCp(T2-T1) • Heat and temperature are related, but they are not the same thing. According to your results, what does the concept of heat energy take into account that temperature does not?