Question

A student in a science lab is investigating heat transfer and thermal energy conservation as she mixes hot and cold water. She first measures out her desired amount of cold water into a Styrofoam cup. She then measures out hot water from the faucet or from a pot hot water on her stove. After she measures the temperature of the hot and cold waters, she pours the hot water into the cold water. She monitors the temperature of the mixed waters and records the final temperature. She uses a standard thermometer to record the temperatures. She does three trials, which are shown below:

Trial 1:
For her first trial, the student decided to mix 250 mL of water at 20 °C with 250 mL of water at 98 °C. After waiting some time, she recorded the temperature of the mix to be 56 °C.
Trial 2:
For her second trial, the student decided to mix 200 mL of water at 20 °C with 400 mL of water at 98 °C. After waiting some time, she recorded the temperature of the mix to be 72 °C.
Trial 3:
For her third trial, the student decided to mix 300 mL of water at 15 °C with 150 mL of water at 90 °C. After waiting some time, she recorded the temperature of the mix to be 41 °C.

Include a data table that organizes the data collected from the three trials.

Make another table, or add to your table, to show data calculations. You will calculate the change in temperatures of the cold and hot water, as well as the mass of the cold and hot waters.

Use the beginning temperature of the hot and cold water and the final temperature of the mixture to calculate the change in temperature of the cold water and the change in temperature of the hot water. For example, the temperature of the cold water was raised from its beginning temperature to the final temperature of the mixture.

Since one milliliter (mL) of water has a mass of one gram (g), it is very easy to determine the mass of the cold and hot water. For example: If you have 100 mL of water, then the mass of the water is 100 g. Remember, 1 kg = 1000 g. Convert the mass of the hot and cold water to kilograms.

Use the equation Q = (m)(c)(Δ T) to calculate the heat gained by the cold water for each trial. Show your work using the problem-solving method shown in previous rubrics. The specific heat for water (c) is 4186 J/(kg * C°).

Use the equation Q = (m)(c)(Δ T) to calculate the heat "lost" by the hot water for each trial. Show your work using the problem-solving method shown in previous rubrics. The specific heat for water (c) is 4186 J/(kg * C°).

Compare the values for heat gain and heat loss in questions 3 and 4.

In an isolated system, the total heat given off by warmer substances equals the total heat energy gained by cooler substances. Now look at your answer to Question 5. What might have caused the difference you have reported? Even though this data was provided to you, think of the errors the student could have encountered when collecting the data.

Write a complete conclusion for this activity.

Answer 1

Answer:.

You might a table similar to this. Apparently one is to compare the heat gain to the heat loss. Usually to calculate the heat gain/loss you have to include the specific heat (1 Cal/(gm deg C) for water. So these values

will only be multiplied by 1 to get gain /loss in calories.

m1 T1 m2 T2 Tf Tf-T1 T2-Tf Gain Loss Diff

250 20 250 98 56 36            42  9000 10500      1500

200 20 400 98 72 52            26 10400 10400          0

In an ideal experiment Heat Loss = Heat Gain

You might also include units in the column headings m1 (gm), etc.

Hope this helps you to get started.