Journal Entry:
Fifty grams of four different metals were heated to 100 ºC then immediately transferred to an insulated container containing 100 grams of water at 25 ºC. When thermal equilibrium was reached, the final temperature of the water was measure and recorded.
| Metal | Initial temp of metal (ºC) | Final temp of metal (ºC) |
| Al | 100 | 32.3 |
| Fe | 100 | 28.8 |
| Cu | 100 | 28.3 |
| Au | 100 | 26.1 |
Which of the following statements can be correctly concluded
from the data?
(A) The temperature change of the water was less than the temperature of the
metal; therefore, the water gained less energy than the metals lost.
(B) The temperature change of the metal was greater than the temperature change
of the water but because the final temperatures of the metal and water were the
same, the total amount of thermal energy transferred was equal.
(C) The temperature change of the water was less than the temperature of the
metal; therefore, the heat capacity of the water is less than the heat capacity
of the metal.
(D) The sum of the initial water and metal temperatures was greater than the sum
of the final water and metal temperatures, indicating a total loss of energy
from the system.
Learning Intentions
We will learn what calorimetery is and how it can be used to calculate the specific heat of an unknown substance and then identify the substance.
We will be able to design and interpret the results of an experiment in which calorimetry is used to determine the change in enthalpy of a chemical process at a constant pressure.
Closing Task:
You can create a pre-lab to address the challenge given.
Content Standards being covered:
Energy is transferred between systems either through heat transfer or through one system doing work on the other system. (EK 5.B.1)
Temperature is a measure of the average kinetic energy of atoms and molecules. (EK 5.A.1)
The process of kinetic energy transfer at the particulate scale is referred to in this course as heat transfer, and the spontaneous direction of the transfer is always from a hot to a cold body. (EK 5.A.2)
When two systems are in contact with each other and are otherwise isolated, the energy that comes out of one system is equal to the energy that does into the other system. The combined energy of the two systems remains fixed. Energy transfer can occur through either heat exchange or work. (EK 5.B.2)
Calorimetry is an experimental technique that is used to determine the heat exchange/transferred in a chemical system. (EK 5.B.4)