Units Conversion
TEMPERATURE
From Kelvin (K) to Celsius (°C ,former centigrade) scale:
T(°C) = T(K) - 273.15
From Kelvin (K) to Fahrenheit (°F) scale:
T(°F) = (T(K)*9/5) - 459.67
From Fahrenheit (°F) to Rankine (°R) scale:
T(°R) = T(°F) + 459.67
ENERGY
1 J (joule) = 1 N·1m = 107 erg
1 cal = 4.184 J
1 kWh(kilowatt hour) = 3.6·106 J
1 BTU(British Thermal Unit) = 1055 J
VOLUME
1 ft3 (cubic feet) = 28.317 L (liters)
1 gal(US)(gallon) = 3.785 L
1 barrel = 42 gal(US) = 158.97 L
Volume/Pressure/Temperature for (ideal) gases
(Pressure) x (Volume) = (n° of moles) x R x (Temperature)
In short : PV=nRT
Pressure in atm. (1 atm = 101325 Pa = 760 mmHg)
Volume in Litres (L)
R = Universal constant = 0.082
Temperature in K
Weight / mol
W=weight of a given sample (solid,liquid or gas) in gram
n =n° of moles
M = molecular weight of the substance (example H2O = 16+1+1=18)
n = W/M (example : in 1.00 L water there are 1000 g and 1000/18=55.55 mol of water)
1 mol = 6.022·1023 particles (molecules or atoms) (example : in 1.00 L water there are 55.55 mol of water and hence 55.55 * 6.022·1023 = 3.34·1025 molecules)
ΔH = ΔU + PΔV ; ΔF = ΔG + PΔV
As usual rule in a chemical reaction, the only variation in volume (ΔV) considered is the difference between volume of gas in reactants and volume of gas in products.
If we call Δn the mole variation (gas moles of products - gas moles of reactants) we can write, according to above relationship,
PΔV = Δn R T
ΔH = ΔU + Δn R T
ΔF = ΔG + Δn R T
