The Chemistry of Natural Waters, Essay Example

Experiment 10 – Chemistry of Natural Waters

Hardened mineralized water is water which possesses elevated amounts of magnesium and calcium salts which respond to other substances and cause precipitation to occur. This aspect causes the hardened mineralized water to become detrimental to human consumption (Wurts, n.d.). The aspect of water hardness can be delineated as the quantity or the amount of the dissolved salts (zinc, iron, magnesium and calcium) which are evident in water. Hardened mineralized water results in a modification of the color and the taste of the drinking water. Hardened water becomes a greater problem when it is applied for washing dishes (Campbell & Peterson, 2010; Community College of Rhode Island, n.d. Leo et al., 2000, Thompson, 2012).

The hardened mineralized water releases a residue in the plumbing systems, electrical appliances and cookware. Notwithstanding, the aspects of hardened mineralized water is a significant quality in the development of fish in their environment because the hardened mineralized water which possess calcium ions performs a significant function in fish skeletal development (Ebrahimpour et al., 2010). The aspect of water hardness is assessed by the classification of dual valence ions which are manif3est in water and measured in parts per million. This measurement can be achieved chemically by the application of several approaches which are EDTA (ethylenediamine tetra acetic acid titrating methods, AA (atomic absorption spectrometry, calorimetric methods and chemical titration (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

The conventional units of assessment are the number of parts per million, number of milligrams per liter and the number of grains which are present in a gallon. This empirical study applies EDTA titrating methods and atomic absorption spectrometry in order to review the characteristics of water hardness (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

In the application of atomic absorption spectrometry (AA) this equipment are implemented in the ascertaining of the concentrations and presence of diverse metallic substances in a liquid sample (Atkins, 2012). These metallic substances may be magnesium Mg²⁺ or calcium Ca²⁺ in the hardened mineralized water samples. There are distinct electronic energy configurations which are possessed by the atoms of each substance. The laboratory assessment equipment reviews the amount of photonic energy which is absorbed reliant on Beer’s law which is a function of the ratio of the saturation of the metallic atoms which are present in the sample. This assessment provides a measurement which is assessed in units of absorbance called nanometers (nm) (Campbell & Peterson, 2010; Leo et al., 2000, Rafferty, 2014; Thompson, 2012).

The examination sample is oxidized and atomized by the laboratory equipment which is sequenced by the analytic procedure. Subsequent to the analysis, the measurement which is provided by the laboratory equipment can be transformed into lines which possess an equation on the calibration graph.  The aspect of the water hardness of the hardened mineralized water is assesses by the application of a TDS value. The distinction between the AA spectrometry and the EDTA titrating methods is that the EDTA provides an analysis of the dual valence ions which are present in the sample while the AA spectrometry method provides an analysis of one dual valence cation at any given instance (Campbell & Peterson, 2010; Leo et al., 2000, Sivasankar , 2008; Thompson, 2012).

The most precise measurement of TDS is the atomic absorption spectrometry method. The demineralization of hardened mineral water can be achieved by a number of distinct approaches. These approaches are the application of a lime carbonate process by means of extensive scale municipal facilities in order to extract the Mg²⁺ and the Ca²⁺ from the water supply. Ion solution paradigms which have the outcome of the creation of an insoluble precipitate are other methods which can be applied (Campbell & Peterson, 2010; Casiday and Frey, 1998; Leo et al., 2000, Thompson, 2012).

In the EDTA titrating methods, the aspect of the water hardness which is an outcome of the manifestation of Ca²⁺ is conveyed in ppm of calcium carbonate (Ca CO ₃) in the water hardiness sample. These chemicals were implemented in the process of titration: EDTA was applied as a salt Na₂H₂C₁₀H₁₂N₂O_4, a solution of NH₃NH₄ which had been applied as a buffer EBT (erichrome back T) and H₄C₁₀H₁₂N₂O₄   which is the chemical designation for EDTA. The process incorporated a three stage process which included the preparation of a conventional calcium solution, a standard EDTA solution and the evaluation of an unrecognized sample of calcium with the EDTA standard solution (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

This experiment includes the calibration of the pH concentration with an ammonium titrating agent and then a titration process which applies Na₂ H₄C₁₀H₁₂N₂O₄ which is the formula for the disodium salt ethylenediamine tetra acetic acid solution in water. The EBT is an indicating agent which is normally blue in its aspect and the chelating agent is the EDTA. The EBT responds with the Mg²⁺ in order to create MgD^– which has the outcome of a pinkish reddish wine colored solution. This reaction does not occur between the EBT and calcium. The bluish aspect is representative of the conclusive point which is the quality that is desired and will be attained by performing serial titrating methods (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

The procedure initiates with the application of NH₃/ NH₄ in order to elevate the hydronium ion content (pH to approximately ten). Subsequently, the EBT is aggregated by applying serial titration of the aqueous solution, which has the outcome a pinkish reddish wine color. At the end, EDTA is aggregated by the application of serial titration to the aqueous so9lurtion. The Ca²⁺ and Mg²⁺ ions which are present in the sample respond s with the REDTAS in order to create CaEDTA and MgEDTA. These ion solutions are colorless. In addition, HD^2- is given as a blue tinted solution, whose outcome with is the genuine form of EBT (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

Conventionally, industrial concerns have selected the implementation of softening agents in order to demineralize the hardened, mineralized water and to diminish their maintenance expenses. In the experiment number ten, there were two softening agents which had been reviewed and examined. These softening agents are the industrial hardened water conditioning product   otherwise known as baking soda and the cation interchange resin. The review demonstrates that the conditioning baking soda product diminished the water mineral hardness by a factor of half whereas the cation interchange resin almost entirely diminished the asp3ect of the water’s hardness. The cation interchange resin functions by interchanging two ions which possess solitary valence (i.e., Na⁺ or H⁺_ with one dual valence ion (i.e., Ca²⁺ or Mg²⁺ethylenediamine tetra acetic acid (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

As a result of the decline in the pH, it was ascertained that the pH ions had been located in the resin. It is a recyclable material and the procedure is reversible in the event that the Na⁺ and the H⁺ are consumed.  In this empirical study, water samples which had been derived from four distinct sources and the aspect of hardness of water had been evaluated by the application of three distinct methods. These methods incorporated the TDS method, the EDTA titrating method and the AA spectrometry method (Welz et al., 2008). The water samples had been labeled as sample C, sample D, sample E and sample F (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

The origins of the water had been Deer Park water, Dasani; Brita treated dormitory water and the untreated tap water, respectively. A hypothesis had been formulated that the sample C and the sample D had been of a softened quality and the sample E and the sample F had been of a hardened quality (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

Methods

The methodology of this empirical study is detailed in the PSU Chemtrek. In the circumstance of the TDS method which incorporates dissolved solids, a small parcel of aluminum foil had been positioned on a heated plate.  Subsequently, a drop of water which had been undiluted, a drop of calcium aqueous solution and the water samples were positioned of distinct locations on the aluminum parcel. The remains had been examined and were compared with the Ca²⁺ which had been the control sample. In the process of AA spectrometry, the adjustment of the absorption of light in contrast to the ion saturation had been accomplished by means of Excel (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

A mathematical formula which represented the line of best fit had been applied in order to transform the values which had been derived from the AA spectrometer to the saturation values which could be interpreted of Mg²⁺ and Ca²⁺. The values which had been applied for the saturation values were applied in moles per liter. This conversion facilitated the transformation for assessment purposes of part per million and the number of grains per gallon of Mg²⁺ and Ca²⁺. Consequently, the values which had been derived as a result of the ionic hardness had been transformed to the hardness assessments of the calcium carbonate. Consequently, these assessments had been contrasted to the values which had been demonstrated in Table 5. This was conducted in order to categorize the aspects of hardness of each of the samples (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

The third method of ascertaining the aspect of the water’s hardness was conducted by means of the EDTA titrating approaches. Good transfer protocols had been applied in order to apply any of the solutions which were implemented in this empirical research. The minute and constant dimension of the drops had been an important consideration while performing this experiment. A litmus well strip which had a dimension of   1 cm x 12 cm was implemented for the titrating process. Initially a drop of the buffer solution which had been composed of NH₃/ NH₄ in addition to EBT hadbeen applied while the water sample had been transferred to each of the wells. Subsequently, a drop of the solution which was EDTA aqueous had been aggregated to the initial well (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

Afterward, another drop had been added to each well. In order to accelerate the reaction, the wells were agitated by the application of a stirrer. As the wells began to change in color, this is what indicated the point where the titration had become effective. A color change was noted in each of the wells. The saturation point had been ascertained by being aware of the initial well which experienced color transformation. This assessment had been converted to parts per million and number of grains per gallon with regards to the dual valence ion. Subsequently, the assessed values had been transformed into the hardness ions of the calcium carbonate molecules (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

In addition, 20 mg of commercial conditioning product (baking soda) had been added to the water and was reviewed by applying the EDTA titrating approach. The final analysis was applying the EDTA titrating methods had been applied after the aggregation of a minute quantity of the cation interchange resin. The hydronium ion (pH) of the solution had been assessed by the application of litmus paper (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

Results

Table 1 Outcome of the TDS Evaluation in Comparison to the Control Reference Sample (CaCl₂)

Table 2 Saturation of the Magnesium and Calcium ions Compared to the absorbance Measurement at a wavelength of 202.5 nm and 422.7 nm

The values which had been derived from the tables had been applied in order to graphically plot the points for the line of best fit.

The mathematical relationship which represents the line of best fit was derived from Fig 1 and had been applied in order to transform the calcium ion values with regards to the absorbance of light which was attained from the AA spectrometry. This equation was y = 0.0104x + 0.0188 [1].

The mathematical equation had been algebraically manipulated in order to attain a v value for x. This value was.In applying the values which were attained from the absorbance measurement it was derived that the number of calcium ions which were manifest in the Sample C (Deer Park water bottle)    was = 2.2211 ppm Ca²⁺. The number of calcium ions which had been present in Sample D (Dasani bottled water) x = 6.2596 ppm Ca²⁺.  The number of calcium ions which had been present in sample E (Brita filtered dorm tap water)    x = 19.625 ppm Ca²⁺. The number of calcium ions which had been present in sample F (Dorm Tap water) x = 38.75 ppm Ca²⁺

The mathematical relationship which represents the line of best fit was derived from Fig 2 and had been applied in order to transform the magnesium ion values with regards to the absorbance of light which was attained from the AA spectrometry. This equation was y = 0.0122x + 0.0127 [2]. The mathematical equation had been algebraically manipulated in order to attain a v value for x. This value was. In applying the values which were attained from the absorbance measurement it was derived that the number of magnesium ions which were manifest in the Sample C was 2.6393 ppm Mg²⁺. In applying the values which were attained from the absorbance measurement it was derived that the number of magnesium ions which were manifest in the Sample D (Dasani bottled water)   was            x = 3.336 ppm Mg²⁺.

The number of magnesium ions which had been present in Sample D (Dasani bottled water) was x = 3.336 ppm Mg²⁺. The number of magnesium ions which had been present in Sample E (Brita filtered tap water) was x = 26.9262 ppm Mg²⁺. The number of magnesium ions which had been present in Sample F (tap water)   was x = 23.2704 ppm Mg²⁺. The measurements from Equation 1 and 2 were transformed to ppm CaCO₃, which is the precise hardness value for the water sample. In applying equation 3 and equation 4 for Ca²⁺ and Mg²⁺, the following formula is derived: [Equation 3]. Computation for the Samples C, D, E and F yields the hardness for each sample. Sample C_hardness = 5.55275 ppm CaCO₃, Sample D_hardness = 15.649 ppm CaCO₃, Sample E_hardness= 49.0625 ppm CaCO₃ and Sample F_hardness = 96.875 ppm CaCO₃.

Computation for the Samples C, D, E and F yields the hardness for each sample. Sample C_hardness = 10.86 ppm CaCO₃, Sample D_hardness = 13.73 ppm CaCO₃, Sample E_hardness= 110.81 ppm CaCO₃ and Sample F_hardness = 95.763 ppm CaCO₃ (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

Table 3 Ionic Saturations of the Magnesium and Calcium Ions in Samples C, D, E and F Including the Hardness Results

Edta titrations

The saturation of the dual valence ions in the water samples had been derived by using equation 5, which relied on the well which first experienced the changes in color (the final point). Equation 5 had been derived from the assumption that at the final point, an equal quantity of moles of EDTA and dual valence ions manifested presence in the sample (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

Considering equation 5 and using the quantity of drops from table 3, the measurements of samples C, D, E and F had been obtained as 4 x 10^-4 M, 8 x 10^-4 M, 1.6 x 10^-3 M and 1.4 x 10^-3 M.  Considering equation 6, the saturation of dual valence ions derived were transformed to ppm.

The water mineral hardness of the samples C, D, E and F in ppm had been computed and found at 40 ppm, 80 ppm, 160 ppm and 140 ppm. Considering the transformation factor in equation 7, the ppm measurements were transformed to grains per gallon.

1 grain per gallon = Water hardness in ppm / 17.1 ppm [Equation 7]

Consequently, the water hardness of samples C, D, E and F in grains per gallon was determined to be as 2.34, 4.678, 9.357 and 8.187 grains per gallon (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

Table 4 details the quantity of drops of EDTA which had been required in order to reach the endpoint for all of the samples. In applying equation 5  for the saturation of dual valence ions, the  values in ppm and grains per gallon applying equations 6 and 7 for  the complete hardness in addition to  the classifications for the water samples (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

Chemical Water Softening Agents

The effects of the chemical water softening agents on the qualities of the hardness of the water samples had been reviewed and calculated in Table 5. The quantity of drops of EDTA which had been to in order to reach the final point was derived by using equation 5 and the  actual hardness was derived by using equation 6 (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

Table 4:  Effect of Water Softening Agents on the Hardness of Water

Discussion

The outcomes which had been derived from TDS methodology (table 1) demonstrate that distilled water created no ring while CaCl₂ (aqueous) sample which was implemented as the referencing point, created a white ring residue. The samples C, D, E and F which had been derived from Deer Park bottle, Dasani water, Brita filtered tap water and unfiltered tap water created a slightly white residue which was not as white as calcium residue. The white residue had been whiter than calcium. The white residue had been less prominent than the residue left by the control CaCl₂ ( aqueous) sample with a  heavier white residue than heavier than the control  CaCl₂ ( aqueous). The complete dissolved salts approach is applied for evaluating the amount of dissolved salts remaining from an evaporated a sample of water (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

The distilled water created no residual ring since it had no dissolved salts present in it. An acknowledged sample of calcium chloride was applied as a reference being it had only calcium ions and chloride ions which would experience evaporation and leave behind a white residual ring. This residual ring in comparison with rings formed by other water sample (C, D, E, and F) demonstrated that as suspected, the samples D and F possessed the highest number of ionic salts. This ration was followed by samples C and E. Notwithstanding; all four samples contained more than one category of salt causing them to have heavier residue rings than the CaCl₂ referencing residues (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

Therefore, these results indicated that the water derived from these sources possessed more dissolved salts than the calcium chloride sample. Accuracy had not been shown by the TDS method of assessing water hardness test due to the attribute it did not demonstrate the precise ions presented in the water sample being examined. Consequently, complementary methods must be accessed in order to provide accurate chemical analysis and results (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

In the testing method of atomic absorption spectrometry, the saturation of dual valence ions measured in parts per million had been determined by transforming the photonic absorbance of calcium and magnesium ions derived from the AA machine. The photonic absorbance rates of the calcium and magnesium ions had been derived and were recorded on Table 3. These experimental values had been used in order to calculate the saturation of the magnesium and calcium ions in equations 1 and 2 and were recorded in Table 4. These experimental values yielded values of 16.4 ppm for sample C when converted to calcium carbonate hardness (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

This estimate is within the range of soft water which is 17.1 and below sample D provided a value of 29.4 ppm which is considered slightly hard. The E and F samples derived a hardness range of 159.87 and 192.6 ppm. The samples E had been found to be within the required hardness range for hard water which is 120 to 180 as indicated by the water hardness scale in Table 3.  Sample F had been found to be within the category of very hard water. Consequently, these results demonstrate that the water which had been derived from the Deer Park water sample was soft. The Dasani samples, Brita filtered water and tap water had been measured as being somewhat hard, hard, and extremely hard (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

Table 5: Water Mineralized Hardness Chart

(Campbell & Peterson, 2000)

AA is an effective instrument which can ascertain the saturation of the elements derived from a sample.  Hence, the results are more accurate portrayed than the other methods. The additional advantage of this method is that the water hardness can be measured in terms of the quantity of dual valence ions. Origins of uncertainty in this experiment may be derived from an erroneous reading of the photonic absorbance and the mixture of the water samples. This particularly holds true if the lab manages a number of dilutions. Uncertainties may also occur as an outcome of the dilutions of the examined sample in the case of the magnesium standards stock being twice diluted (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

EDTA outcomes demonstrated   the saturation of dual valence ions in the sample C, sample D, sample E, and sample F. Assuming that indicators had been used to reach the endpoint; the calculations of the sample C, sample D, sample E, and sample F were measured to be 40 ppm, 80 ppm, 160 ppm, and 140 ppm. This aspect demonstrates that the water sample C was somewhat hardened; the sample D was moderately hardened and the samples E and F were extremely hardened. The EDTA titrating agent CalVer 2 (hydroxy naphtha blue) is conventionally used in conjunction with Eriochrome Blue-Black or murexide indicator (ammonium purpurate). The hydronium ion (pH) had been elevated to a level of 10 in order to facilitate the precipitation of magnesium during the titrating process (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

Research has shown that EDTA titration demonstrates errors occurring from erroneous drop size/ erroneous titration volumes, contaminations taking place during the solution preparation and the use of erroneous indicators. This approach relies on exact volumetric assessments and significant human intervention. These characteristics may result in additional errors. Considering the outcomes in equation 6, the saturation of the calcium ions had been found to be 120 ppm of CaCO₃ which is within the specified range of water hardness in accordance with Table 5. The precision and accuracy of this analysis is not dependable due to its reliance on the establishing of the endpoint. If the endpoint is determined with errors, consequently the results of the water’s hardness will be inaccurate (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

Water specificity, temperature and conductivity during each of the sampling sites are a few of the aspects which may influence the outcomes of the three approaches of ascertaining the water’s hardness. Transient hardness is demonstrated by bicarbonates being present. Hard water can also be made soft by boiling. Permanent water hardness is manifested by the saturation of calcium and magnesium ions. The water’s hardness can be removed by performing ion interchange in addition to other methods (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

Considering the outcomes from the distinct methods of evaluating the water hardness, the water samples hardness had been ordered in sequence from the aspects of softness to the hardness: samples C, D, F and E. This water hardness order makes sense, due to the attributes of the bottled water being treated prior to bottling. This is performed in order to provide the water with a decreased index of hardness. The water samples which had been taken from the dormitory are assumed to be harder. This is a result of the water’s flowing to the dorm by means of pipes which do not have residue filters. The deficiency of filters and treatment will not decrease the water’s hardness which has been enhanced by minerals which are found in the residues in the pipes (Campbell & Peterson, 2010; Leo et al., 2000, Thompson, 2012).

Conclusion

The precise numerical measurement of the quantities of each of the ions (Ca²⁺ and Mg²⁺) is more effectively found by the Atomic Absorption spectrophotometry approach of water hardness examination. This approach had been found to be more accurate than the TDS method and EDTA perspectives. The outcomes which had been derived from the AA spectrophotometry examination demonstrate that sample C was softest, D was slightly hardened, and E and F were hardened and extremely hardened. Conversely, the EDTA approach demonstrated that the samples possessed varying degrees of water hardness. The TDS approach had been restricted to showing the presence of undissolved salts in the distinct water samples. Consequently, it can be perceived that AA approach yielded the most precise methods as its measurements had been reviewed to be within the standardized range. The initial hypothesis was proven to be significant.

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