Question

Which conditions are equal to STP?
30°C, 100 kPa
–273.15°C, 1 atm
0°C, 760 mmHg
25°C, 101.325 kPa

Answer 1

STP is most commonly defined as 0°C (273.15 K) and 1.00 atm (101.325 kPa).

- 0°C, 760 mmHg — yes (760 mmHg = 1 atm).
- 25°C, 101.325 kPa — no (pressure = 1 atm but temperature = 25°C, not 0°C).
- 30°C, 100 kPa — no (both temperature and pressure differ; 100 kPa ≈ 0.987 atm).
- −273.15°C, 1 atm — no (−273.15°C is absolute zero, not STP).

Note: some references use 1 bar (100 kPa) as a “standard” pressure for other purposes, but the conventional STP above is 0°C and 1 atm.