from empirical fits, and one function that returns water vapour pressure (simply interpolates based on the previously available dataset).master
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% Generated by roxygen2: do not edit by hand |
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% Please edit documentation in R/chemistry-tools.R |
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\name{OxygenSolubilityWater} |
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\alias{OxygenSolubilityWater} |
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\title{Oxygen solubility in water} |
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\usage{ |
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OxygenSolubilityWater(temperature) |
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} |
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\arguments{ |
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\item{temperature}{numeric, vector. In degrees Celsius.} |
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} |
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\value{ |
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a dataframe with the following columns: |
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+ "temperature" same as the supplied temperature |
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+ "g/cm-3" oxygen solubility expressed as gram per cubic cm |
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+ "mg/L" ditto expressed as milligram per litre |
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+ "mol/L" ditto expressed as moles per litre (molarity) |
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+ "permoleculewater" number of O2 molecules per molecule of water |
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Note: mg/L is equivalent to ppm by weight (since water has approx |
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unit density in the temperature range 0-50 Celsius). |
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} |
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\description{ |
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Oxygen solubility in water which is in contact with |
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air saturated with water vapour, as a function of |
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temperature and at a total pressure of 760 torr. |
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} |
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\details{ |
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Some background: as the temperature of a gasesous solution is raised the |
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gas is driven off until complete degassing occurs at the boiling point |
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of the solvent. This variation of solubility with temperature can be |
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derived from thermodynamic first principles. |
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But the variation of oxygen solubility in water cannot be represented by a |
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simple relationship (derived from thermodynamic first principles), and so |
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more complicated expressions which are fitted to empirical data have |
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to be used. |
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|
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Hitchman, Measurement of Dissolved Oxygen, 1978 reproduce a table by |
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Battino and Clever (1966) that presents experimental values of the |
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so-called Bunsen absorption coefficient (this is the volume of gas, at 0 C |
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and 760 torr, that, at the temperature of measurement, is dissolved in one |
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volume of the solvent when the partial pressure of the gas is 760 torr) |
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recorded by eleven research groups up until 1965. The standard error of the |
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mean value is never greater +-0.5%. The mean values from this table are |
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probably accurate enough for most applications. |
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Hitchman notes that the data in this table can be fitted by two forms of |
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equations: one form obtained from Henry's law (under the restriction that |
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the partial pressure of the gas remains constant), and another form by |
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describing the variation with temperature by fitting a general power series. |
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The latter approach is used in this function. |
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|
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Hitchman chooses to fit a fourth degree polynomial, and found that the |
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square of the correlation coefficient was 0.999996. |
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|
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For more background and detailed derivation of the formula used here, |
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see section 2.2 (pp. 11) in Hitchman. |
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|
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This formula is strictly speaking only valid for 0 < T < 50 celsius. |
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The function will return values outside this range, but with a warning. |
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} |
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\examples{ |
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\dontrun{ |
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OxygenSolubilityWater(22) |
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OxygenSolubilityWater(c(2, 7, 12, 30)) |
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} |
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} |
@ -0,0 +1,25 @@ |
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% Generated by roxygen2: do not edit by hand |
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% Please edit documentation in R/chemistry-tools.R |
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\name{VapourPressureWater} |
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\alias{VapourPressureWater} |
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\title{Vapour pressure of water} |
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\usage{ |
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VapourPressureWater(temperature) |
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} |
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\arguments{ |
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\item{temperature}{numeric vector, in degrees Celsius} |
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} |
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\value{ |
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vapour pressure of water, in kilopascal |
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} |
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\description{ |
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Vapour pressure of water as a function of temperature |
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This function returns the vapour pressure of water at the given |
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temperature(s) from the common::vapourwater dataset. |
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} |
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\examples{ |
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\dontrun{ |
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VapourPressureWater(45) |
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VapourPressureWater(c(20, 25, 45, 60)) |
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} |
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} |
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