Question

The standard temperature used in thermochemical reactions is……………
(A.) 273K
(B.) 298K
(C.) 297K
(D.) 303K

Answer 1

Hint: Try to recall the meaning of STP and temperature and pressure associated with it. Also, remember this temperature is also equal to zero degrees celsius.

Complete step by step solution:
We know that the temperature, pressure, and concentration of reactants and products affect the amount of measured energy. The scientific community has agreed upon a temperature of 273 K and 1 atm as the standard temperature and pressure (STP).
So, we can say at standard temperature and pressure, a system is said to have a temperature of zero degrees centigrade (273 Kelvins) and the pressure equal to the atmosphere is always 1 atm. Additionally, one mole of any gas at STP occupies a volume of 22.414 L. Remember, this concept only holds true for gases.

Therefore, we can conclude that the correct answer to this question is option A.

Additional information: In chemistry, IUPAC changed the definition of standard temperature and pressure (STP) in 1982. Until 1982, STP was defined as a temperature of 273.15 K and an absolute pressure of exactly 1 atm.

Note: We should also know the difference between NTP and STP. NTP stands for Normal Temperature and Pressure and STP stands for Standard Temperature and Pressure. As we already know STP is set by the IUPAC as 0$^{ 0 }$C and 100 kPa or 1 bar. NTP is set at 101.325 kPa but uses 20$^{ 0 }$C as the temperature.