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T1 Complexometric assay for water hardness: an interactive lab experiment.
A1 Milla González, Miguel
A2 Química Analítica
K1 water analysis
K1 water hardness
K1 Ca and Mg in natural waters
K1 complexometry
K1 complexometric titration
K1 EDTA
K1 water hardness by complexometry
K1 water hardness assay
K1 eriochrome black T
K1 interactive lab experiment
K1 simulated determination of water hardness
AB Water hardness is due to the presence of multivalent metal ions. In natural waters, the most abundant ions are calcium(II) and, in less amount, magnesium(II). Cations such as Fe(III), Al(III), Mn(II) and other metal ions also contribute to hardness, although their concentration level is much below the concentration level of calcium. Water hardness is a parameter of interest in water analysis, since it has adverse consequences in a great deal of human activities related to the use of this natural resource. The most widely employed assay for water hardness is complexometry. When hardness in water is determined by complexometry, the obtained value accounts for all multivalent metal ions present in the sample. Very often, the result is given as calcium carbonate equivalent per liter. In this simulated lab experiment, the complexometric titration of hardness in a water sample is carried out. All steps of the titration are covered, from the weighing of the titrant (EDTA as disodic salt) to the final calculation of the hardness parameter. The analyst can titrate the sample several times and enter the obtained values of the calculated mg/L of calcium carbonate equivalent for each titration. A final table shows and compares both the values calculated by the system and those calculated and entered by the analyst. An introduction shows the chelating properties of EDTA and a simulation of the the theoretical background of the titration is presented.
YR 2011
FD 2011-08-22T00:00:00Z
LK http://hdl.handle.net/10498/14127
UL http://hdl.handle.net/10498/14127
LA eng
DS Repositorio Institucional de la Universidad de Cádiz
RD 10-may-2026