Which variables are related by the combined gas law?

• A. Pressure, volume, and number of moles
• B. Volume, temperature, and number of moles
• C. Pressure, temperature, and density
• D. Pressure, volume, and temperature

Answer: (D)

Verified step by step guidance

1. Recall that the combined gas law relates the pressure (P), volume (V), and temperature (T) of a fixed amount of gas, combining Boyle's, Charles's, and Gay-Lussac's laws into one expression.
2. Understand that the combined gas law assumes the amount of gas (number of moles, n) remains constant, so n is not a variable in this relationship.
3. The combined gas law formula is given by \(\frac{P_1 \times V_1}{T_1} = \frac{P_2 \times V_2}{T_2}\), showing how pressure, volume, and temperature change relative to each other.
4. Note that density and number of moles are not directly part of the combined gas law; density relates mass and volume, and number of moles is constant in this law.
5. Therefore, the variables related by the combined gas law are pressure, volume, and temperature.