What type of calorimeter is known for measuring heat at atmospheric pressure?

The coffee cup calorimeter is specifically designed to measure heat changes at constant atmospheric pressure. This type of calorimeter typically consists of two Styrofoam coffee cups nested together to provide insulation, with a thermometer inserted to monitor temperature changes during a reaction or process.

When a reaction occurs within the coffee cup calorimeter, the heat absorbed or released is measured under the assumption that the pressure remains constant—matching the conditions of many biological and chemical processes. This characteristic makes it particularly useful for educational demonstrations and experiments where changes in enthalpy are evaluated at atmospheric pressure.

In contrast, a bomb calorimeter operates at constant volume, which is suitable for measuring combustion reactions but not for reactions that occur under atmospheric pressure. Constant volume calorimeters, as the name suggests, are designed to maintain a fixed volume, making them unfit for atmospheric pressure measurements. Refrigerated calorimeters are not standard terminology within calorimetry and do not specifically refer to a defined method for measuring heat at atmospheric pressure. This distinction clarifies why the coffee cup calorimeter is the correct choice for measuring heat under atmospheric pressure conditions.