Which equation represents Charles' Law?

Which equation represents Charles' Law?

• A. V1/T1 = V2/T2
• B. P1V1 = P2V2
• C. V = kT
• D. PV = nRT

Answer: (A)

Charles' Law describes how a gas's volume changes in direct proportion to its absolute temperature when pressure stays the same. In two states, that relationship is written as V1/T1 = V2/T2, with temperatures measured in Kelvin so that the ratio makes physical sense all the way to absolute zero. This equation exactly expresses the idea that as the temperature increases (in Kelvin) at constant pressure, the volume increases in proportion, and the ratio of volume to temperature remains constant. The other forms point to related gas laws but not this specific condition: P1V1 = P2V2 is Boyle's Law, which ties volume to pressure at constant temperature. PV = nRT is the general ideal gas law, which brings in amount of gas and the gas constant. V = kT shows a direct V–T relationship but omits the explicit constant-pressure condition and the two-state ratio that defines Charles' Law in typical problems.

Charles' Law describes how a gas's volume changes in direct proportion to its absolute temperature when pressure stays the same. In two states, that relationship is written as V1/T1 = V2/T2, with temperatures measured in Kelvin so that the ratio makes physical sense all the way to absolute zero. This equation exactly expresses the idea that as the temperature increases (in Kelvin) at constant pressure, the volume increases in proportion, and the ratio of volume to temperature remains constant.

The other forms point to related gas laws but not this specific condition: P1V1 = P2V2 is Boyle's Law, which ties volume to pressure at constant temperature. PV = nRT is the general ideal gas law, which brings in amount of gas and the gas constant. V = kT shows a direct V–T relationship but omits the explicit constant-pressure condition and the two-state ratio that defines Charles' Law in typical problems.