Calorimetry, Thermal Equilibrium & Energy Calculations
Complete all problems showing your work. Use the heat transfer equation \(q = mc\Delta T\) and the principle that heat lost = heat gained. Check your answers when finished.
Calorimetry Data Table
Use this data for Problems 7-11:
| Trial | Mass (g) | Ti Metal (C) | Ti System (C) | V Metal (mL) | Ti Cal H2O (C) | V Cal H2O (mL) |
|---|---|---|---|---|---|---|
| 1 | 282.25 | 100 | 22 | 20 | 20 | 170 |
| 2 | 121.94 | 100 | 24 | 4 | 19 | 150 |
| 3 | 107.47 | 100 | 21 | 3 | 20.5 | 150 |
| 4 | 77.88 | 100 | 20 | 2 | 19.5 | 150 |
| 5 | 146.89 | 100 | 23 | 1 | 19 | 150 |
Ti = Initial Temperature, V = Volume, Ti System = Final Temperature (at thermal equilibrium)
Problem 1
Justify the reasoning behind the assumption that a metal placed in boiling water will eventually attain the same temperature as the boiling water.
Problem 2
Outline why it is important to transfer the heated metal to the calorimeter as quickly as possible.
Problem 3
Describe how the volume of water could be used to determine its mass.
Problem 4
The method states that the thermometer should be checked regularly until thermal equilibrium has been reached. Suggest how an experimenter will know when thermal equilibrium has been attained and state the necessary measurement that is obtained from it.
Problem 5
Explain the reasoning for changing the calorimeter water before each trial.
Problem 6
Outline three realistic solutions that could minimize heat losses in this experiment.
Problem 7
Show, using the data from each trial, the determination of volume and density of the metal. Show your work for at least one trial.
Problem 8
Show, using data from each trial, the calculation for the specific heat (with appropriate units) of the metal. Show your work for at least one trial.
Hint: Use \(q = mc\Delta T\) and remember that heat lost by metal = heat gained by water
Problem 9
Calculate the average specific heat and density from all five trials.
Problem 10
Suggest, with a reason/reference to your lab work, a possible identity for the unknown metal.
Reference common metals: Lead (11.3 g/cm³, 0.128 J/g°C), Copper (8.96 g/cm³, 0.385 J/g°C), Iron (7.87 g/cm³, 0.449 J/g°C), Aluminum (2.70 g/cm³, 0.89 J/g°C)
Problem 11
Calculate the percent error for the experimental specific heat and density determination (assuming the metal is lead with actual specific heat = 0.128 J/g°C and density = 11.3 g/cm³).
Problem 12
A 45.0 g sample of water is heated from 15.0°C to 75.0°C. How much heat energy was absorbed? (\(c_{\text{water}} = 4.18\) J/g°C)
Problem 13
A 125 g piece of iron at 200°C is placed in 500 g of water at 25°C. What is the final temperature when thermal equilibrium is reached? (\(c_{\text{iron}} = 0.449\) J/g°C, \(c_{\text{water}} = 4.18\) J/g°C)
Problem 14
An unknown metal with a mass of 85.0 g at 100°C is placed in 150 g of water at 22.0°C. The final temperature is 28.5°C. Calculate the specific heat of the unknown metal.
Problem 15
How much heat is released when 250 g of aluminum cools from 150°C to 25°C? (\(c_{\text{aluminum}} = 0.89\) J/g°C)