wbmix_sa {titrationCurves}

Titration Curve for Weak Base Mixture

Description

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 Principles of Quantitative Chemical Analysis (McGraw-Hill, 1997).

Usage

wbmix_sa(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, ...)

Arguments

conc.base1

Molar concentration of the first monoprotic weak base analyte; defaults to 0.10 M.

conc.base2

Molar concentration of the second monoprotic weak base analyte; defaults to 0.10 M.

conc.acid

Molar concentration of the strong acid titrant; defaults to 0.10 M.

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.

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.

pkw

The pKw (or pKs) value for the solvent; defaults to water as a solvent with a pKw of 14.

vol.base

Initial volume, in mL, of the solution that contains the weak base; defaults to 50.00 mL.

plot

Logical; if TRUE, plots the titration curve.

eqpt

Logical; if TRUE, draws a vertical line at the titration curve's equivalence point.

overlay

Logical; if TRUE, adds the current titration curve to the existing titration curve.

...

Additional arguments to pass to plot() function.

Value

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(s)

David T. Harvey, DePauw University. [e-mail]

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)