Which of the following correctly defines the conditions for standard temperature and pressure (STP) in chemistry?

• A. 0°C and 760 mmHg
• B. 0°C and 1 atm
• C. 25°C and 1 atm
• D. 273 K and 1 atm

Answer: (D)

Verified step by step guidance

1. Understand that Standard Temperature and Pressure (STP) is a set of conditions commonly used in chemistry to define a reference state for gases.
2. Recall that the standard temperature is defined as 0°C, which is equivalent to 273 K. This is important because temperature in gas law calculations must be in Kelvin.
3. Recognize that the standard pressure at STP is 1 atmosphere (atm), which is equivalent to 760 mmHg or 760 torr. These units are interchangeable but 1 atm is the conventional unit used in STP definitions.
4. Combine these two conditions to define STP as 0°C (273 K) and 1 atm pressure. This is the internationally accepted standard for STP in chemistry.
5. Note that 25°C and 1 atm is often used as Standard Ambient Temperature and Pressure (SATP), which is different from STP.