Carbon dioxide, CO₂, is a molecule utilized in a variety of fields. Biologically, it plays an important role as a waste product in animal respiration. CO₂ is transported through the blood stream of the body in the form of carbonic acid. The equilibrium is shown below.

Reaction 1

As a solid, CO₂ is more commonly known as “dry ice” and has a normal phase transition temperature less than the 0°C observed for regular ice. Most notably, at sea level dry ice goes directly from its solid phase to the gas phase.

In order to further explore the properties of CO₂, a student performed a calorimetry experiment. The student measured the change in temperature of the substance while adding a prescribed amount of heat to the system. This process was repeated using H₂S, SiO₂ and C₂H₂. The student then determined the specific heat, c, of each molecule using the following equation:

q = mcΔT

Equation 1

The findings are listed below in Table 1.

Table 1Summary of calorimetry experiment listing the specific heat of various substances