trated acid to keep it present as RSO 3 H since the concentrated acid will

Trated acid to keep it present as rso 3 h since the

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trated acid to keep it present as RSO 3 H since the concentrated acid will provide it an excess of H + which will bind to the resin’s sulfonyl groups. (Smith and Chang, 1983). Since there will be excess H + present, the resin will be present as RSO 3 H since it will shift the equilib- rium to the left. (Equation 1). HCl was used since it is a more accessi- ble concentrated strong acid, and since it is a strong acid, it will disso- ciate completely. The liquid was not allowed to flow below the resin level at all times. The resin must always be dissolved in water in order for it to have its impurities dissolved in water. (Rieman, Walton. 1970). Also, the resin is suspended in water in order for its hydrophobicity to be re- duced since it is merely a nonpolar compound with a polar ligand. (The DOW Company, n.d.). Another rea- son why it is suspended in water is because, it prevents the formation of air pockets between the resin parti- cles which may reduce the number of binding sites which will lead to a more inefficient column. (Smith, Frank. 1983). Once the resin was in- side the column, it was washed with distilled water and pH was tested by catching the latest eluate drop in a watch glass and moisting a pH paper with it. This was done in order for the solution to have a neutral pH. Having a neutral pH will ensure that the H + present in the solution will only come from the H + bound to the resin. This will reduce the error of calculating the amount of Cu 2+ con- centration will only depend on the amount of H + released once Cu 2+ binds to the resin. (Skoog, et. al., 2004.). Determination of the Total Cation Concentration To prepare for the determination of the total Cation concentration present in the unknown solution, 0.10 M standardized NaOH titrant was first prepared. Then, 100 mL of 3 M HCl from the excess 3 M HCl from the previous experiments was prepared. After which, 10 mL of the unknown solution was transferred via pipette to the prepared column. A 250-mL Erlenmeyer flask was used as the receiving flask which will con- tain the displaced H + that will be titrated with NaOH. The stopcock was then calibrated to ensure that the flow is 30 drops per minute. This is done in order to provide enough time for the Cu 2+ ions to bind to the resin surface and displace the H + . A very fast rate flow will result to mini- mal exchange, while a very slow rate flow may lead to better separation, but the results may not be observ- able under normal operating condi- tions. (Skoog,, 2004). Once the rate flow has been set, the remain- ing solution was poured into the col- umn while the eluate is being col- lected into the receiving flask. Next, the column was washed with dis- tilled water until its pH was equal to the pH of the distilled water. Note that the washings were being caught in the same flask as the beaker and that the column was always being washed as the eluate was collected in order to prevent the formation of air pockets that would reduce the efficiency of the resin when it will be next used. The washing and the col-
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