Discuss the below:
Introduction
Hardness of water is denoted as the concentration of multivalent cations, with added significant for calcium (Ca+2) and magnesium (Mg+2) ions as they typically cause water hardness. Furthermore, water hardness is imperative to control because it poses real world problems like the feeling of soap once it is applied. Hard water tends to feel "gritty" when applied while soft water feels "slimy". Water hardness can be determined or calculated using the equation:
Hardness = ([Ca+2] + [Mg+2])(2eq/mole)
Or, in terms of CaCO3, Hardness = ([Ca+2] + [Mg+2])(2eq/mole) (50,000 mg CaCO3 per eq.)
Where, [Ca+2] and [Mg+2] are the molar concentration of the calcium and magnesium ions present in the water.
Even though water hardness is not a very concerning issue, it still poses a problem for consumers. Water hardness is to blame for the residue left behind on bathroom walls, sinks, and other utilities. It can go as far as to block pipes because the buildup does not permit for water to pass. This buildup is usually calcium deposits which must be attended to often to prevent blockage. Additionally, consumers take extra safety precautions and measures such as installations of filters on shower and sink faucets to lessen the effects of hard water.
Also, it ought to be noticed that water hardness can turn into a wellbeing problem when present in extreme conditions and concentrations. Calcium and magnesium particles morph chemically into CaCO2 and Mg(OH)2. Likewise, the residue causes scale buildup in pipework. Scale can cause a few more issues. Scale buildup in valves can keep them from sealing appropriately. Some common classifications of water hardness include: soft water, slightly hard water, moderately hard water, hard water, and very hard water. They vary according to concentrations.
In addition, hard water tends to produce something known as soap curd, an accumulation that can cause aggravation and disease to the skin. Furthermore, soap curd present in water that is utilized while washing clothes can cause bad odors and make it harder to clean.
The overall goal of this lab is to acquaint students with the concept of water hardness and the threats it poses. Additionally, student should be able to measure the hardness of different water samples. The (n) of EDTA titrant will be determined using the standard CaCO3 composition.
Water hardness can generally be characterized as the grouping of calcium and magnesium particles found inside a given water test, generally expressed in terms of calcium carbonate (CaCO3). In spite of the fact that hardness is not a huge concern, it is critical as to the arrangement of precipitates as a result of the issues that they can bring about.
2. Equipment/Apparatus and Procedures
In order to determine the normality of the EDTA titrant, in units of mg/L as CaCO3, students will be required to use either 0.10 mg CaCO3 per mL or1.00 mg CaCO3 per mL. Firstly, a pipet should be used to add 50 mL of the standard CaCO3 solution to the Erlenmeyer flask. Next, Hach hardness 1 buffer solution should be added to the solutions and mixed. Similarly, the ManVer 2 Hardness Indicator Powder Pillow should be added and mixed. Hardness measurements are conducted very similarly. Use a graduated cylinder to extract 50 mL of the test solution and that sample should be placed in an Erlenmeyer flask. Then, 2 mL of the Hach hardness 1 buffer solution should be added. Next, ManVer 2 Hardness Indicator Powder Pillow should be mixed in. The sample should be titrated to the blue color of the EBT like the Normality of the EDTA Titrant test.
The specimen will be titrated with EDTA titrant until some change in color appears, more specifically form dark red to blue. The first and last titrant level in the burette should be used to determine the total amount used at the end. The normality of the titrant can be found through the equation:
NEDTA = ((0.100 mg Ca?CO?_2 per mL )(∀_(Ca-Standard)))/(∀_ETA titrated)
Here, NEDTA is the normality of the EDTA titrant in units of mg/L. VCa-Standard is the volume of CaCO3 standard used in mL and VEDTA is the volume of EDTA used in units of mL.
The hardness can be determined using the formula:
H = ((V_EDTA)(N_EDTA)(100 (mg/L)/(mg/mL)))/V_s , where: H is the total hardness of the sample and Vs is the volume of the sample.