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Water hardness, soap precipitation

A second problem with hard water is that these metals react with soap molecules and form a scum to which bathtub rings, etc., are attributed. Hard water is therefore not the best water to use for efficient soapy water cleaning processes, since the metal-soap precipitation reaction competes with the cleaning action. Water softeners assist with solving this problem too. [Pg.122]

In hard water areas all over the world, it is difficult to make the soap lather. Instead, the water becomes cloudy. This cloudiness is caused by the presence of a solid material (a precipitate) formed by the reaction of the dissolved substances in the water with soap (basically sodium stearate) and it is a real problem. This white precipitate is known as scum (Figure 11.35). [Pg.199]

The usefulness of soaps is limited by their tendency to precipitate out of solution in hard water. Hard water is water that is acidic or that contains ions of calcium, magnesium, or iron. In acidic water (such as the acid rain of environmental concern), soap molecules are protonated to the free fatty acids. Without the ionized carboxylate group, the fatty acid floats to the top as a greasy acid scum precipitate. [Pg.1207]

Remember that an arrow pointing upward indicates a gas that has been released and an arrow pointing downward indicates a precipitate. The Greek letter delta over the arrow shows heat. Magnesium sulfate also makes water hard, but you can t soften this type of hard water by boiling it. You must add another chemical to react with the sulfate impurity which prevents the soap from forming suds. Sodium tetraborate and potassium carbonate are chemicals that will do this. Here are the equations showing how they act ... [Pg.42]

As noted above, soaps form precipitates when used in hard water. In the 1930s, chemists developed synthetic detergents as a substitute for soap to avoid this problem. Synthetic detergents can be used in hard water without forming precipitates. Today, almost all laundry products and shampoos contain synthetic detergents. [Pg.503]

Hard water contains Fe +, Ca +, and/or Mg + ions, all of which displace Na+ from soaps to form precipitates. This removes the soap from the water and puts an undesirable coating on the bathtub or on the fabric being laundered. Synthetic detergents are soap-like emulsifiers that contain sulfonate, —SOj, or sulfate, —OSOj, instead of carboxylate groups, —COO . They do not precipitate the ions of hard water, so they can be used in hard water as soap substitutes without forming undesirable scum. [Pg.581]

Precipitation of a solid from a solution can result from a chemical change. Using soap with hard water produces a precipitate called soap scum because the soap reacts chemically with ions in the water. [Pg.191]

Synthetic detergents are more active cleaners than soaps. They don t form precipitates with Ca+2 and Mg+2 ions in hard water and are therefore more effective cleaners in hard water than soaps. [Pg.167]

Acidic bathroom cleaners have some distinct advantages on common bathroom soils. First, the main matrix for the soil referred to as soap scum is soap that has been precipitated by water hardness ions. Imbedded in this matrix may be skin flakes, lint, dirt, etc. (see Figure 13.7), but the waxy precipitated soap serves to hold the mass together and make it adhere to surfaces. Acids can work to reverse this chemical reaction, turning some part of the soap fatty acids into liquid components (notably oleic acid). This serves to soften the soil overall and thereby make it more easily removed. Second, if there were any ion bridging of the soil to a receptive... [Pg.608]

EDTA is used to prevent pesticides from precipitation in hard-water solutions, to soften water in soap and detergent, and to prevent the catalytic effects of metal ions present in water in the cold rubber SBR process [57]. EDTA attached to iron catalyzes the direct hydroxylation of phenolic compounds [58] it also is the best way to supply iron-deficient citrus trees [59]. Other chelating agents include nitrilotriacetic acid (NTA) made from ammonia and diethylenetriamine pentacetic acid from diethylenetriamine [60]. [Pg.272]

Detergents have been developed to avoid this problem of soap in hard water. Their structures are similar to (although more varied than) that of soap, but they are less likely to form insoluble compounds with hard water ions. Some detergents are ionic like soap, and some are molecular. For example, in sodium dodecyl sulfate (SDS), a typical ionic detergent, the -C02 portion of the conventional soap structure is replaced by an -0S03 group, which is less likely to link with hard water cations and precipitate from the solution ... [Pg.587]

Hard soaps consist essentially of the sodium salts of palmitic, stearic and oleic acids. As the calcium and magnesium salts of these acids are insoluble in water, soap does not immediately pass into solution and form a lather with hard water. The soap dissolved reacts with the metallic salts in solution and the corresponding salts of the fatty acids are precipitated. This process continues until all the metals which form insoluble soaps are precipitated. The reaction which takes place is illustrated by that between sodium palmi-tate and calcium chloride —... [Pg.135]

A detergent has a sulfonate ionic head while a soap has a carboxylate ionic head. This difference is responsible for the difference in utilization in hard water. Ca ", Mg, Fe, and Fe sulfonates are water-soluble whereas the carboxylates are water-insoluble. The detergent molecules stay in solution in hard water and exert their cleansing action. Soap molecules cannot exert their cleansing action in hard water because they precipitate out in the form of their Ca, Mg ", Fe ", and Fe " carboxylates. [Pg.304]

A) Soap cannot hydrolyze in hard water, so it precipitates. [Pg.93]

Correct choice (B) describes this process. Choice (D) is an incorrect variation. It is not the dirt in the hard water that is precipitating with the soap, it is previously dissolved ions. Choice (C) gives incorrect assumptions about the both the acidic nature of solutions required by soap and the basic property of hard water. Choice (A) uses a somewhat familiar term, hydrolysis, but it is used incorrectly in this case. Hydrolysis for the stearate ion describes the interaction of the ion with water to produce the conjugate acid and release hydroxide ions, not a factor in forming the observed precipitate. ... [Pg.93]

Hardness in water is caused by the presence of dissolved calcium and magnesium compounds, such as calcium hydrogencarbonate or magnesium sulfate. The hardness of the water can be gauged by its ability to form a thick lather with soap. Water that lathers easily is called soft, whereas water that produces very little lather and a scum, is termed hard. Soap (see page 175) is sodium stearate and scum forms as a result of the precipitation of an insoluble stearate ... [Pg.198]

The presence of Ga +, Mg " ", Fe , or Mn ions will impart hardness to water. Hardness is objectionable because (1) it causes precipitates (scale) to form in boilers and hot-water systems, (2) it causes soaps to form insoluble... [Pg.242]


See other pages where Water hardness, soap precipitation is mentioned: [Pg.535]    [Pg.437]    [Pg.396]    [Pg.149]    [Pg.231]    [Pg.600]    [Pg.632]    [Pg.874]    [Pg.64]    [Pg.875]    [Pg.876]    [Pg.885]    [Pg.82]    [Pg.1208]    [Pg.99]    [Pg.149]    [Pg.319]    [Pg.3084]    [Pg.231]    [Pg.1116]    [Pg.11]    [Pg.11]    [Pg.13]    [Pg.16]    [Pg.583]    [Pg.7]    [Pg.782]    [Pg.276]    [Pg.200]    [Pg.149]    [Pg.701]   


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