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All values refer to 25 °C and to the thermodynamically stable standard state at that temperature unless noted. Values from CRC refer to "100 kPa (1 bar or 0.987 standard atmospheres)".
A calorimeter constant (denoted C cal) is a constant that quantifies the heat capacity of a calorimeter. [1] [2] It may be calculated by applying a known amount of heat to the calorimeter and measuring the calorimeter's corresponding change in temperature.
The centigrade heat unit (CHU) is the amount of heat required to raise the temperature of one pound (0.45 kg) of water by one Celsius degree. It is equal to 1.8 Btu or 1,899 joules. [26] In 1974, this unit was "still sometimes used" in the United Kingdom as an alternative to Btu. [27]
Chemical formula Δ f H ⦵ /(kJ/mol) Acetone: Liquid C 3 H 6 O: −248.4 Benzene: Liquid C 6 H 6: 48.95 Benzoic acid: Solid C 7 H 6 O 2: −385.2 Carbon tetrachloride: Liquid CCl 4: −135.4 Carbon tetrachloride: Gas CCl 4: −95.98 Ethanol: Liquid C 2 H 5 OH −277.0 Ethanol: Gas C 2 H 5 OH −235.3 Glucose: Solid C 6 H 12 O 6: −1271 ...
Vapor-pressure formula for ammonia: [4] log 10 P = A – B / (T − C), where P is pressure in kPa, and T is temperature in kelvins;
This is an accepted version of this page This is the latest accepted revision, reviewed on 3 March 2025. This article is about the chemical element. For other uses, see Sulfur (disambiguation). Chemical element with atomic number 16 (S) Sulfur, 16 S Sulfur Alternative name Sulphur (pre-1992 British spelling) Allotropes see Allotropes of sulfur Appearance Lemon yellow sintered microcrystals ...
T is the temperature, T TPW = 273.16 K by the definition of the kelvin at that time; A r (Ar) is the relative atomic mass of argon and M u = 10 −3 kg⋅mol −1 as defined at the time. However, following the 2019 revision of the SI , R now has an exact value defined in terms of other exactly defined physical constants.
Here is a similar formula from the 67th edition of the CRC handbook. Note that the form of this formula as given is a fit to the Clausius–Clapeyron equation, which is a good theoretical starting point for calculating saturation vapor pressures: log 10 (P) = −(0.05223)a/T + b, where P is in mmHg, T is in kelvins, a = 38324, and b = 8.8017.