Determining The Specific Heat Of Two Different Metals
Purpose
Using a calorimeter, the experiment aimed to determine the specific heat of two different metals, Lead and Zinc, in order to calculate their individual atomic weight.
Theory
The calorimeter consists of a metal outer cup, a removable metal inner cup, which is held in place by a rubber ring, and an insulating lid with a small opening for a thermometer. It is a closed system as the air between the inner cup and outer cup insulates the water and heated metal, so, ideally, all heat is contained within the calorimeter (1). Early calorimeters based on water or ice date back to the 18th century as a laboratory technique to measure the heats of chemical reactions and phase changes. In the early 19th century, the calorimeter was further developed by the chemist Samuel Wilson Parr to its present form (2). …show more content…
The law was formulated in 1819, allowing the atomic weights of many elements to be originally calculated by the specific heat (3). Today, the atomic weights of elements are determined using mass spectrometry.
The specific heat of the metal samples, , the water in the calorimeter, , and the cup, (J/gºC), is calculated using , where Q is the quantity of heat (J), m is the mass (g) of the sample, and ∆T is the change in temperature (ºC). In a calorimeter, the heat from the metal raises the temperature of the water to an equilibrium, so that the quantity of heat of the metal is equal to the combined heat of the water and inner cup, shown as Qm=Qw+Qc, which can also be written as and solved for . Using this value, the atomic weight of the metals is calculated using the Law of Dulong and Petit, .
Using a calorimeter, the experiment aimed to determine the specific heat of two different metals, Lead and Zinc, in order to calculate their individual atomic weight.
Theory
The calorimeter consists of a metal outer cup, a removable metal inner cup, which is held in place by a rubber ring, and an insulating lid with a small opening for a thermometer. It is a closed system as the air between the inner cup and outer cup insulates the water and heated metal, so, ideally, all heat is contained within the calorimeter (1). Early calorimeters based on water or ice date back to the 18th century as a laboratory technique to measure the heats of chemical reactions and phase changes. In the early 19th century, the calorimeter was further developed by the chemist Samuel Wilson Parr to its present form (2). …show more content…
The law was formulated in 1819, allowing the atomic weights of many elements to be originally calculated by the specific heat (3). Today, the atomic weights of elements are determined using mass spectrometry.
The specific heat of the metal samples, , the water in the calorimeter, , and the cup, (J/gºC), is calculated using , where Q is the quantity of heat (J), m is the mass (g) of the sample, and ∆T is the change in temperature (ºC). In a calorimeter, the heat from the metal raises the temperature of the water to an equilibrium, so that the quantity of heat of the metal is equal to the combined heat of the water and inner cup, shown as Qm=Qw+Qc, which can also be written as and solved for . Using this value, the atomic weight of the metals is calculated using the Law of Dulong and Petit, .