Calcium ions in hard water

Sodium C rbon te. Sodium carbonate softens water by forming insoluble calcium carbonate with calcium ions in hard water. Carbonate can also reduce calcium levels by ion pairing, although the benefit to detergency is questionable. Buildup of calcium carbonate on machine and fabrics, which can occur with time, is undesirable. Sodium carbonate [497-19-8] does not provide any suspending action. It does, however, provide alkalinity to the wash hquor and is an effective alkah. 

Causes kettles to fur Calcium ions in hard water are required by the body for bones and teeth... 

Why is hard water so hard to lather Ordinary soap is often sodium stearate, NaCi7H3502. Sodium stearate consists of the sodium salt of a compound that contains many carbon atoms. The calcium ions in hard water displace the sodium ions, and the new salts are insoluble ... 

The United States Public Health Service (USPHS) recommends the fluoridation of water as a means for preventing tooth decay. The recommended concentration is 1 mg F"/L. The presence of calcium ions in hard water can precipitate the added fluoride. What is the maximum molarity of calcium ions in hard water if the fluoride concentration is at the USPHS recommended level (Ksp for CaF2 = 4.0 X 10-11.)... 

Zeolites are useful to soften hard water. Calcium ions in hard water are exchanged with sodium ions in zeolites. 

Water softeners often replace calcium ions in hard water with sodium ions. Since sodium compounds are soluble, the presence of sodium ions in water does not result in the white, scaly residues caused by calcium ions. However, calcium is more beneficial to human health than sodium. Calcium is a necessary part of the human diet, while high levels of sodium intake are linked to increases in blood pressure. The Food and Drug Administration (FDA) recommends that adults ingest less than 2.4 g of sodium per day. How many liters of softened water, containing a sodium concentration of 0.050% sodium by mass, have to be consumed to exceed the FDA recommendation (Assume a density of 1.0 g/mL for water.)... 

Calcium ion, along with magnesium and sometimes iron(II) ion, accounts for water hardness. The most common manifestation of water hardness is the eurdy precipitate formed by the reaction of soap, a soluble sodium salt of a long-chain fatty acid, with calcium ion in hard water ... 

A very important ligand (or chelating agent) for titrimetric analysis is the ethylenediaminetetraacetate (EDTA) ligand. It is especially useful in reacting with calcium and magnesium ions in hard water such that water hardness can be determined. The next section is devoted to this subject. 

Soaps react with the calcium and magnesium ions in hard water to produce soap curd that greatly reduces its effectiveness. The curds are actually insoluble calcium and magnesium salts. Synthetic laundry detergents have replaced soap for cleaning clothes in the last half century. Synthetic detergents are made from petroleum. They work like soap except they do not react with magnesium and calcium ions to form insoluble precipitates and salts. 

Interest in detergent products derived from renewable resources and with better biodegradability has driven evaluation of oxidized sugars and starches as builders or co-builders in detergents.113 Builders and co-builders complex calcium and magnesium ions in hard water to prevent sealing or deposits due to precipitation of insoluble carbonate salts. In current powder detergents, the builders are usually zeolites used in combination with polycarboxylate polymers derived from synthetic acrylic-maleic acid copolymers.114... 

Such a molecule can cause particles of grease or oil to mix somewhat with water and to be washed from a dirty article. Calcium and magnesium ions in hard water react with stearate ions to form a solid, yielding soap scum. To avoid this problem, chemists developed synthetic detergents that do not form insoluble salts with calcium and magnesium ions. Synthetic detergents are similar to soaps in that they have an ionic end and a large hydrocarbon-like end. 

The city s Public Works Department is investigating new sources of water. One proposal involves drilling wells into a nearby aquifer that is protected from brackish water by a unique geological formation. Unfortunately, this formation is made of calcium minerals. If the concentration of calcium ions in the water is too high, the water will be "hard," and treating it to meet local water standards would be too expensive for us. 

For example, hard water is caused by the presence of calcium and magnesium ions in solution. Sodium aluminosilicate is a water softener which replaces the calcium and magnesium ions in hard water with sodium ions ... 

Calcium carbonate is a chemical compound with the formula of CaCO. It is a common substance found in rocks. It is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. Calcium carbonate is the active ingredient in agricultural lime, and is created when Ca ions in hard water react with carbonate ions, creating limescale. It is commonly used medicinally as a calcium supplement or as an antacid, but excessive consumption can be hazardous. 

Permutit A compound that can soften water. It does this by exchanging its sodium ions for the calcium and magnesium ions in hard water. It consists of sodium aluminum silicate. It is a zeolite. The sodium ions do not form insoluble salts with soap and therefore do not prevent the formation of a lather. The Permutit can be returned to its original state by soaking in brine. 

To avoid these undesirable effects, some people install water softeners in their homes. These devices are charged with sodium ions, usually from sodium chloride, that exchange with the calcium and magnesium ions in hard water. Sodium ions do not form scaly deposits as calcium and magnesium do, and they do not react with soap. However, sodium does increase the risk of high blood pressure and must therefore be avoided by those who have high blood pressure or heart problems. 

Certain impurities often found in tap water reduce the effectiveness of soap. Particularly troublesome are the calcium and magnesium ions in hard water. These ions react with soap molecules to form a slimy, gray scum called curd that deposits on skin when bathing or on the sides of the bathtub producing bathtub ring ... 

A good builder must be able to remove most of the calcium present in hard water by chelation, precipitation, or ion exchange. Moreover, as calcium generally helps soils cling to cotton by bridging, sequestering these alkaline earths helps to loosen them. It is, therefore, important to measure calcium sequestration. 

Sodium carbonate is soluble, but calcium carbonate and magnesium carbonate are not (see the solubility rules in Table 4.1). Consequently, the carbonate anions react with dissolved Mg and Ca ions in hard water to form solids that precipitate from (or come out oO solution ... 

The increase of the conductivity (k) by the addition of sodium chloride is known to reduce the cell voltage U at constant current density due to the decrease of the ohmic resistance of wastewater. Energy consumption, which is proportional to U.I, will therefore decrease. Chloride ions could significantly reduce the adverse effects of other anions, such as HCQj -and SO4 2-, for instance by avoiding the precipitation of calcium carbonate in hard water that could form an insulating layer on the surface of the electrodes and increase the ohmic resistance of the electrochemical cell (Chen et aL, 2004). Chloride anions can also be oxidized and give active chlorine forms, such as hypochlorite anions, that can oxidize pollutants. The main mechanism is as follows ... 

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