Nothing
#' Titration Curve for Weak Base Mixture
#'
#' This function calculates and plots the titration curve for a
#' mixture of two monoprotic weak base using a monoprotic
#' strong acid as the titrant. The calculation uses a single master
#' equation that finds the volume of titrant needed to achieve a fixed
#' pH, as outlined in R. de Levie's \emph{Principles of Quantitative
#' Chemical Analysis} (McGraw-Hill, 1997).
#'
#' @param conc.base1 Molar concentration of the first monoprotic
#' weak base analyte; defaults to 0.10 M.
#'
#' @param conc.base2 Molar concentration of the second monoprotic
#' weak base analyte; defaults to 0.10 M.
#'
#' @param conc.acid Molar concentration of the strong acid titrant;
#' defaults to 0.10 M.
#'
#' @param pka1 The pKa value for the first monoprotic weak base
#' analyte's conjugate weak acid; defaults to a pKa of 6, or a pKb of
#' 8.
#'
#' @param pka2 The pKa value for the second monoprotic weak base
#' analyte's conjugate weak acid; defaults to a pKa of 9, or a pKb of
#' 5.
#'
#' @param pkw The pKw (or pKs) value for the solvent; defaults to water
#' as a solvent with a pKw of 14.
#'
#' @param vol.base Initial volume, in mL, of the solution that
#' contains the weak base; defaults to 50.00 mL.
#'
#' @param plot Logical; if TRUE, plots the titration curve.
#'
#' @param eqpt Logical; if TRUE, draws a vertical line at the titration
#' curve's equivalence point.
#'
#' @param overlay Logical; if TRUE, adds the current titration curve
#' to the existing titration curve.
#'
#' @param \dots Additional arguments to pass to \code{plot()} function.
#'
#' @return A two-column data frame that contains the volume of titrant
#' in the first column and the solution's pH in the second column. Also
#' produces a plot of the titration curve with options to display the
#' equivalence point and to overlay titration curves.
#'
#' @author David T. Harvey, DePauw University. \email{harvey@@depauw.edu}
#'
#' @export
#'
#' @importFrom graphics plot lines
#'
#' @examples
#' ### Simple titration curve with equivalence points
#' ex10 = wbmix_sa(eqpt = TRUE)
#' head(ex10)
#'
#' ### Overlay titration curves using different pKa values
#' wbmix_sa(pka1 = 5, pka2 = 8, eqpt = TRUE)
#' wbmix_sa(pka1 = 4, pka2 = 7, overlay = TRUE)
#' wbmix_sa(pka1 = 6, pka2 = 9, overlay = TRUE)
wbmix_sa = function(conc.base1 = 0.1, conc.base2 = 0.1,
conc.acid = 0.1, pka1 = 6, pka2 = 9, pkw = 14,
vol.base = 50, plot = TRUE, eqpt = FALSE,
overlay = FALSE, ...) {
veq1 = conc.base1 * vol.base/conc.acid
veq2 = conc.base2 * vol.base/conc.acid
ka1 = 10^-pka1
ka2 = 10^-pka2
kw = 10^-pkw
ph = seq(pkw, 1, -0.01)
h = 10^-ph
oh = kw/h
delta = h - oh
alpha1 = h/(ka1 + h)
alpha2 = h/(ka2 + h)
volume = vol.base *
(conc.base1 * alpha1 + conc.base2 * alpha2 + delta)/
(conc.acid - delta)
df = data.frame(volume, ph)
df = df[df$volume > 0 & df$volume < 2 * (veq1 + veq2), ]
rownames(df) = 1:nrow(df)
if (plot == TRUE) {
if (overlay == FALSE){
plot(df$volume, df$ph, type = "l", lwd = 2,
xlim = c(0, 1.5 * (veq1 + veq2)), ylim = c(0, pkw),
xlab = "volume of strong acid (mL)", ylab = "pH",
xaxs = "i", yaxs = "i", ...)
}else{
lines(df$volume, df$ph, type = "l", lwd = 2, ...)
}
if (eqpt == TRUE) {
x1 = c(veq1, veq1)
x2 = c(veq1 + veq2, veq1 + veq2)
y = c(0, pkw + 1)
lines(x1, y, type = "l", lty = 2, col = "red")
lines(x2, y, type = "l", lty = 2, col = "red")
}
}
invisible(df)
}
Any scripts or data that you put into this service are public.
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.