How To Solve Calorimetry Problems Assignment In
Scientists use well-insulated calorimeters that all but prevent the transfer of heat between the calorimeter and its environment.
This enables the accurate determination of the heat involved in chemical processes, the energy content of foods, and so on.
Before we practice calorimetry problems involving chemical reactions, consider a simpler example that illustrates the core idea behind calorimetry.
Suppose we initially have a high-temperature substance, such as a hot piece of metal (M), and a low-temperature substance, such as cool water (W).
Assume the specific heat of steel is approximately the same as that for iron (Table 1 in Chapter 5.1 Energy Basics), and that all heat transfer occurs between the rebar and the water (there is no heat exchange with the surroundings).
Solution The temperature of the water increases from 24.0 °C to 42.7 °C, so the water absorbs heat.
Check Your Learning A 248-g piece of copper is dropped into 390 m L of water at 22.6 °C.
Check Your Learning A 92.9-g piece of a silver/gray metal is heated to 178.0 °C, and then quickly transferred into 75.0 m L of water initially at 24.0 °C.(Note: You should find that the specific heat is close to that of two different metals.Explain how you can confidently determine the identity of the metal).That heat came from the piece of rebar, which initially was at a higher temperature.Assuming that all heat transfer was between the rebar and the water, with no heat “lost” to the surroundings, then = 248 °C, so the initial temperature of the rebar was 248 °C.Check Your Learning A 248-g piece of copper initially at 314 °C is dropped into 390 m L of water initially at 22.6 °C.Assuming that all heat transfer occurs between the copper and the water, calculate the final temperature.After 5 minutes, both the metal and the water have reached the same temperature: 29.7 °C.Determine the specific heat and the identity of the metal.One technique we can use to measure the amount of heat involved in a chemical or physical process is known as calorimetry.Calorimetry is used to measure amounts of heat transferred to or from a substance.