GED Science TestPhysical ScienceMedium
A scientist is studying the behavior of an ideal gas. If the temperature of a fixed amount of gas in a sealed container is doubled (from 273 K to 546 K) while its volume is kept constant, what will happen to the pressure of the gas?
- AThe pressure will be quadrupled.
- BThe pressure will remain the same.
- CThe pressure will be doubled.
- DThe pressure will be halved.
Show answer & explanationAnswer & explanation
Correct answer: C. The pressure will be doubled.
According to Gay-Lussac's Law (a specific case of the Ideal Gas Law where volume and moles are constant), for a fixed amount of gas at constant volume, the pressure of the gas is directly proportional to its absolute temperature (P₁/T₁ = P₂/T₂). If the absolute temperature is doubled, the pressure will also double.
Why the other options are wrong
- A. This implies a squared relationship, which is not the case for pressure and temperature in this scenario.
- B. This would only happen if the gas was not ideal or if the conditions were not changed.
- D. This would happen if the temperature was halved, or if an inverse relationship like Boyle's Law was incorrectly applied.
Gay-Lussac's Law
Gay-Lussac's Law states that for a fixed amount of gas at constant volume, the pressure of the gas is directly proportional to its absolute temperature (measured in Kelvin).
- P₁/T₁ = P₂/T₂
- Volume and number of moles (amount of gas) are constant
- Temperature must be in Kelvin (absolute temperature)
- Pressure increases with increasing temperature
Memory trick: Gas laws are 'PTVN' (Pressure, Temp, Volume, Moles).