Name Section Date CONCEPTUAL PHYSICAL SCIENCE Thermal Energy and Thermodynamics Temperature Mix Experiment Water's Heat Capacity Purpose To predict the final temperature of a mixture of cups of water at different temperatures Apparatus 3 Styrofoam cups liter container with a wide mouth thermometer (Celsius) pail of cold water pail of hot water Discussion If you mix a pail of cold water with a pail of hot water, the final temperature of the mixture will be between the two initial temperatures. What information would you need to predict the final temperature? You'll begin with the simplest case of mixing equal masses of hot and cold water. Procedure Step 1: Begin by marking your three Styrofoam cups equally at about the three-quarter mark. You can do this by pouring water from one container to the next and marking the levels along the inside of each cup. Step 2: Fill the first cup to the mark wi water to the same level. Measure and record t th hot water from the pail, and fill the second cup with cold he temperature of both cups of water. Temperature of cold water = Temperature of warm water = Step 3: Predict the temperature of the water when the two cups are combined. Then pour the two cups of water into the liter container, stir the mixture slightly, and record its temperature. Predicted temperature = _._.__.___ Actual temperature of water = if there was a difference between your prediction and your observation. what may have caused it? Pour the mixture into the sink or waste pail. (Don't be a klutz and pour it back into either of the pails of cold or hot water!) Now you'll investigate what happens when unequal amounts of hot and cold water are combined. 75 ' TEMPERATURE MIX CONE Step 4: Fill one cup to its mark with cold water from the pail. Fill the other two cups to their marks with hot water from the other pail. Measure and record their temperatures. Predict the temperature of the water when the three cups are combined. Then pour the three cups of water into the liter container, stir the mixture slightly, and record its temperature. Purpose Predicted temperature = Actual temperature of water =_ Pour the mixture into the sink or waste pail. Again, do not pour it back into either of the pails of cold or hot water! a. How did your observation compare with your prediction? bundle or Short studby b. Which of the water samples (cold or hot) changed more when it became part of the mixture? In terms of energy conservation, suggest a reason why this happened. Step 5: Fill two cups to their marks with cold water from the pail. Fill the third cup to its mark with Discussion hot water from the other pail. Measure and record their temperatures. Predict the temperature of Suppose you have cold feet the water when the three cups are combined. Then pour the three cups of water into the liter imroughout the night. Wow container, stir the mixture slightly, and record its temperature. equal mass of nails at the sa Predicted temperature =_ energy will do the better jok 10693019 Actual temperature of water = Procedure Pour the mixture into the sink or waste pail. (At this point, you and your lab partners may simply Consider the equal masses pour waste water back into either of the pails of cold or hot water.) wil do a better job of heat a. How did your observation compare with your prediction? Experiment b. Which of the water samples (cold or hot) changed more when it became part of the mixture? Suggest a reason why this happened. Blep 1: Fill two cups 1/3 fu hey contain equal masses Summing Up Make sure your bundle of 1. What determines whether the equilibrium temperature of a mixture of two amounts of water water? will be closer to the temperature of the initially cooler water or to that of the initially warmer 2. How does the formula Q = cmAT apply here? TEMPERATURE MIX 76