Physics · Ch 8 — Heat and Thermodynamics
Calorimetry
Calorimetry
Calorimetry is the measurement of the heat released or absorbed by a system during a heating process. If a hot body is placed in contact with a colder one and no heat escapes to the surroundings, the heat lost by the hot body exactly equals the heat gained by the cold one: . This is measured practically using a calorimeter, an insulated vessel of water with a thermometer and stirrer (Figure 8.9); dropping a sample of mass , specific heat , at temperature into calorimeter water of mass , specific heat , at temperature (Figure 8.10), both reach a common final temperature Example 8.7 works this out for 5 L of 50°C water mixed with 4 L of 30°C water, giving ; the text also notes that for equal masses of the same subs …
What this figure shows. A cutaway diagram of a standard laboratory calorimeter: an outer insulating wooden casing surrounds a layer of trapped air (acting as extra insulation), inside which sits the metal calorimeter cup filled with water, with a thermometer dipped into the water to read its temperature and a stirrer used to keep the water well-mixed so its temperature is uniform throughout. The whole assembly is built specifically to prevent any heat from escaping to (or entering from) the outside surroundings, which is exactly t …
What this figure shows. The same calorimeter cutaway as Figure 8.9 (insulating casing, trapped-air layer, calorimeter cup, thermometer, stirrer), but now with a small solid sample block shown being lowered into the water. The sample, initially heated to a high temperature T1, is dropped into the calorimeter's water which starts at room temperature T2; the figure sets up the exact scenario the calorimetry final-temperature formula is derived for, where heat flows from the hot sample into the cooler water until both re …