vol2mol function

Calculate Moles of a Gas

vol2mol calculates the moles of a gas for a measured volume, temperature, and pressure.

vol2mol(vol, gas = "CH4", temp, pres, rh = 0, 
        unit.temp = getOption('unit.temp', 'C'), 
        unit.pres = getOption('unit.pres', 'atm'), 
        tp.message = TRUE)

Arguments

• vol: measured gas volume in mL. Numeric vector.
• gas: chemical formula of gas. Currently options are c("CH4", "CO2", "N2", "H2"). Character vector.
• temp: temperature of gas at time of volume measurement. Numeric vector.
• pres: pressure of gas at time of volume measurement, in the units specified in unit.pres (default of atm). Numeric vector.
• rh: relative humidity of the gas at time of measurement. Length one numeric vector between zero and 1.0. Default is zero (dry gas).
• unit.temp: temperature units. Options are "C" (degrees Celcius, the default), "F", and "K". Length-one character vector.
• unit.pres: pressure units. Options are "atm" (the default), "Pa", "kPa", "hPa", and "bar". Length-one character vector.
• tp.message: should a message display temp and pres to avoid unit mistakes? Length one logical vector.

Details

This function uses a simple and approximate approach for the conversion, based on Charles's and Boyle's laws, with NIST values for 0 degrees C and 1.0 atm taken as the reference state (Lemmon et al. 2011). Measured volume is normalized to 1.0 atm and 0 degrees C using stdVol, and the result is divided by the molar volume at the same conditions, as reported by NIST. Resulting error should be within 0.5% for temperature and pressure close to ambient, and is usually below 0.2%.

Returns

gas amount in moles as a numeric vector.

References

Lemmon EW, McLinden MO, Friend DG. Thermophysical Properties of Fluid Systems. In Linstrom PJ, Mallard WG, editors. Chemistry WebBook, NIST Standard Reference Database Number 69. Gaithersburg, MD: National Institute of Standards and Technology, 2011.

Author(s)

Sasha D. Hafner

See Also

vol2mass, mass2vol, options

Examples

# Assume we have measured 253 mL CH4 at 1.0 atm and 22 C, dry
vol2mol(253, "CH4", temp = 22, pres = 1)

# Compare to results to NIST values for the least ideal gas
# Results are within 0.5%
# Expect 0.04108 mol
vol2mol(1000, "CO2", temp = 25, pres = 1)

# Expect 0.08258 mol
vol2mol(1000, "CO2", temp = 25, pres = 2)

# Expect 0.07482 mol
vol2mol(1000, "CO2", temp = 55, pres = 2)