When soap is at the surface of water, the hydrophobic tail of soap will not be soluble in water and the soap will align along the surface of water with the ionic end in water and hydrocarbon tail protruding out of water. Inside the water, these molecules have a unique orientation that keeps the hydrocarbon portion out of the water.
This is accomplished by forming clusters of molecules in which the hydrophobic tails are in the interior of the cluster and the ionic ends are on the surface. This formation is called micelle. Soap in the form of a micelle is able to clean, since the oily dirt will be collected in the centre of micelle. AIM To study the comparative cleaning capacity of a sample of soap in soft and hard water.
THEORY Water that does not contain a significant amount of dissolved minerals such as compounds of calcium and magnesium is soft water. It produces lather with a little amount of soap.
Calcium and magnesium hydrogen carbonates, chlorides and sulphates in water render it hard. When soap is added to hard water, it does not form lather. The calcium and magnesium salts in hard water react with soap and form scum, which is insoluble and floats on top of water. Due to the formation of scum, which is calcium or magnesium salt of soap soap is sodium or potassium salt of fatty acidssoap becomes ineffective in solution and no cleansing occurs. The equations involved in the formation of scum are as follows:.
As the calcium and magnesium salts in water react with soap, cleansing power of soap is reduced and its foaming capacity also decreases. Using a dropper pour 5 ml of tap water in test tube A, and 5 ml distilled water in the other test tubes labelled as B, C, D and E.
Chemistry of Hard and Soft Water
To test tube C, D and E add a pinch of calcium hydrogencarbonate, calcium chloride and calcium sulphate respectively using a spatula. Mix the solution well using a glass rod. Using a dropper, add 3 ml of soap solution to the test tube A. Measure the length of the solution present in the test tube A and record this in table. Shake test tube A, ten times by placing thumb on its mouth.
Observe whether foam is formed by shaking the test tube and record your observations. Measure the length of content foam and solution present in the test tube immediately with the help of a measuring scale. Repeat steps 8 to 11 with the remaining water samples B, C, D and E and record your observations. Production of foam depends on the free availability of hydrophobic portion of the soap. In hard water due to formation of scum hydrophobic portion of the soap gets trapped.
Therefore, hard water is not suitable for cleaning purpose. Question 1: What is hard water? Answer: Hard water is the water that has high mineral content and produces scum on addition of soap.
Question 2: What is soft water? Answer: The water which has low mineral content and produces lather on mixing soap to it is called soft water. Question 3: Why does hard water produce scum when soap is added to it? Question 5: Give the equation involved in the formation of scum. Question 6: Does the presence of all salts of calcium and magnesium cause hardness in water? Answer: No. Question 7: Which salts cause hardness in water?
Answer: The hydrogencarbonates, chlorides and sulphates of calcium and magnesium cause hardness in water. Question 8: Which ions are present in soft water? Answer: Only sodium ion is present in soft water. Question 9: Which out of hard water or soft water is better for cleansing?
Answer: Soft water.Soaps and detergents consist of a large hydrocarbon taill with a negatively charged head as shown in figures. The hydrocarbon tail is hydrophobic water-hating or water repelling and negatively charged head is hydrophilic water-loving. In aqueous solution, water molecules being polar in nature, surround the ions and not the hydrocarbon part of the molecule.
When a soap or detergent is dissolved in water, the molecules associate together as clusters called micelles as shown in figure. The tails stick inwards and the heads outwards. In cleansing, the hydrocarbon tail attaches itself to oily dirt. When water is agitated Shaken vigorously ,the oily dirt tends to lift off from the dirty surface and dissociate into fragments. This gives opportunity to other tails to stick to oil.
The solution now contains small globules of oil surround by detergent molecules. The negatively charged heads present in water prevent the small globules from coming together and form aggregates. Thus, the oily dirt is removed. In the past, detergents caused pollution in rivers and waterbodies. The long carbon chain present in detergents used earlier, contained lot of branching.
These branched chain detergent molecules were degraded very slowly by the micro-organims present in sewage discharge septic tanks and water bodies. Thus, the detergents persisted in water for long time and made water unfit for aquatic life. Nowadays, the detergents are made up of molecules in which branching is kept at minimum.
These are degraded more easily than branched chain detergents. Aim: To compare the effectiveness of the cleansing action of soap and detergent in hard water. Problem statement: Is the cleansing action of a detergent more effective than a soap in hard water? Variables: a Manipulated variables: Soap and detergent solutions b Responding variable : The oily stains on a cloth c Controlled variables : Volume and concentration of magnesium sulphate solution, volume and concentration of cleaning agent Operational definition: The ability of a cleaning agent to remove oily stains on a cloth indicates that the cleaning agent is effective.
Apparatus: cm 3 beaker, 50 cm 3 measuring cylinder. Conclusion: The cleansing action of a detergent is more effective than a soap in hard water. The hypothesis is accepted.
Economics Notes for class 11th statistics. Economics Notes for class 11th Development. Economics Notes for class 12th Vyashti.
Economics Notes for class 12th Samashti. Chapter 4. Carbon and It's Compounds. The soap molecules, thus form structures called micelles. This formation is called a micelle. There are important roles of ends of soap molecules for formation of the structure of Micelle.
Differences between hydrophilic end and hydrophobic end :.
CBSE Notes for Class 10 Science chapter 4. Carbon and its Compounds in english Medium
The cleaning process is characterised by soap micelle. The ionic end of soap is dissolves in water and other end dissolves in oily scum and thus forms structure of micelles. Thus micelles are able to clean as soap because oily scums gather in the center of micelles. There forms emulsion in the water.
The detergent is more effective even in hard water:. Thus, they remain effective in hard water. Differences between soap and detergent:. See other sub-topics of this chapter:. Presence of carbon.Chemically detergents are sodium salts of sulphonic acids,i.
All rights reserved. Carbon and its Compounds. Share with your friends. Ankur Pandey answered this. View Full Answer. Shubham Kumar answered this. Ch answered this.
Priya answered this.
Ritika Sipani answered this. Anand Sah answered this. John answered this. Mihir Jain answered this. Detergents are sodium salt of a long chain benzene sulphonic acid which has cleansing properties.
Shikhar Sachdev answered this. Detergents are the sodium or ammonium salts of long-chain sulphonic acids. P Manoj answered this. Shakti answered this. Ream Bisht answered this. Shashi answered this. Detergents are sodium salts of a long chain sulphonic acids or sulphates. Santosh Narayanan answered this. Detergents is the sodium salt of a long chain Benzene Sulphonic acid which has cleansing properties in water.
Examples of detergents are : Sodium n-dodecyl benzene sulphonate and sodium n-dodecyl sulphate Cleansing action of detergent is same as soap.Carboxylic acids and salts having alkyl chains longer than eight carbons exhibit unusual behavior in water due to the presence of both hydrophilic CO 2 and hydrophobic alkyl regions in the same molecule. Such molecules are termed amphiphilic Gk.
Fatty acids made up of ten or more carbon atoms are nearly insoluble in water, and because of their lower density, float on the surface when mixed with water. Unlike paraffin or other alkanes, which tend to puddle on the waters surface, these fatty acids spread evenly over an extended water surface, eventually forming a monomolecular layer in which the polar carboxyl groups are hydrogen bonded at the water interface, and the hydrocarbon chains are aligned together away from the water.
This behavior is illustrated in the diagram on the right. Substances that accumulate at water surfaces and change the surface properties are called surfactants. Alkali metal salts of fatty acids are more soluble in water than the acids themselves, and the amphiphilic character of these substances also make them strong surfactants. The most common examples of such compounds are soaps and detergents, four of which are shown below. Note that each of these molecules has a nonpolar hydrocarbon chain, the "tail", and a polar often ionic "head group".
The use of such compounds as cleaning agents is facilitated by their surfactant character, which lowers the surface tension of water, allowing it to penetrate and wet a variety of materials. The oldest amphiphilic cleaning agent known to humans is soap.Electrolytic Refining of Metals - #aumsum
Soap is manufactured by the base-catalyzed hydrolysis saponification of animal fat. Before sodium hydroxide was commercially available, a boiling solution of potassium carbonate leached from wood ashes was used. Soft potassium soaps were then converted to the harder sodium soaps by washing with salt solution.
The importance of soap to human civilization is documented by history, but some problems associated with its use have been recognized. One of these is caused by the weak acidity pKa ca. Solutions of alkali metal soaps are slightly alkaline pH 8 to 9 due to hydrolysis. If the pH of a soap solution is lowered by acidic contaminants, insoluble fatty acids precipitate and form a scum. A second problem is caused by the presence of calcium and magnesium salts in the water supply hard water.
These divalent cations cause aggregation of the micelles, which then deposit as a dirty scum. These problems have been alleviated by the development of synthetic amphiphiles called detergents or syndets. By using a much stronger acid for the polar head group, water solutions of the amphiphile are less sensitive to pH changes.
Also the sulfonate functions used for virtually all anionic detergents confer greater solubility on micelles incorporating the alkaline earth cations found in hard water. Variations on the amphiphile theme have led to the development of other classes, such as the cationic and nonionic detergents shown above.
Cationic detergents often exhibit germicidal properties, and their ability to change surface pH has made them useful as fabric softeners and hair conditioners. These versatile chemical "tools" have dramatically transformed the household and personal care cleaning product markets over the past fifty years.You've heard the terms "hard water" and "soft water, but do you know what they mean? Is one type of water somehow better than the other?
What type of water do you have? This article looks at the definitions of these terms and how they relate to water in everyday life. Hard water is any water containing an appreciable quantity of dissolved minerals. Soft water is treated water in which the only cation positively charged ion is sodium. The minerals in water give it a characteristic taste.
Some natural mineral waters are highly sought for their flavor and the health benefits they may confer. Soft water, on the other hand, may taste salty and may not be suitable for drinking. If soft water tastes bad, then why might you use a water softener? The answer is that extremely hard water may shorten the life of plumbing and lessen the effectiveness of certain cleaning agents.
When hard water is heated, the carbonates precipitate out of solution, forming scales in pipes and tea kettles. In addition to narrowing and potentially clogging the pipes, scales prevent efficient heat transfer, so a water heater with scales will have to use a lot of energy to give you hot water.
Soap is less effective in hard water because it reacts to form the calcium or magnesium salt of the organic acid of the soap. These salts are insoluble and form grayish soap scum, but no cleansing lather. Detergents, on the other hand, lather in both hard and soft water. Calcium and magnesium salts of the detergent's organic acids form, but these salts are soluble in water. Hard water can be softened have its minerals removed by treating it with lime or by passing it over an ion exchange resin.
The ion exchange resins are complex sodium salts. Water flows over the resin surface, dissolving the sodium. The calcium, magnesium and other cations precipitate onto the resin surface. Sodium goes into the water, but the other cations stay with the resin. Very hard water will end up tasting saltier than water that had fewer dissolved minerals. Most of the ions have been removed in soft water, but sodium and various anions negatively charged ions still remain. Water can be deionized by using a resin that replaces cations with hydrogen and anions with hydroxide.
With this type of resin, the cations stick to the resin and the hydrogen and hydroxide that are released combine to form pure water.
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Soaps And Detergents - Cleansing Action Of Soaps And Detergents
She has taught science courses at the high school, college, and graduate levels.To save this word, you'll need to log in. But what does a coronavirus cleanup look like? Send us feedback. See more words from the same year Dictionary Entries near detergent deter deterge detergency detergent deteriorable deteriorate deteriorated into.
Accessed 14 Apr. Keep scrolling for more More Definitions for detergent detergent. Entry 1 of 2 : having a cleansing action detergent. Please tell us where you read or heard it including the quote, if possible. What does capricious mean? Test Your Knowledge - and learn some interesting things along the way. Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free! When is 'whom' the right choice?
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Is Singular 'They' a Better Choice? Come look at pictures of baby animals. Can you correctly identify these flowers? Can you spell these 10 commonly misspelled words? Do you know the person or title these quotes describe? Login or Register. Save Word. Log In. Synonyms Example Sentences Learn More about detergent. Keep scrolling for more. Examples of detergent in a Sentence Noun We have tried different laundry detergents. Recent Examples on the Web: Noun Soft furnishings, according to the guidelines, should be cleaned with hot water and detergentfollowed by steam cleaning that reaches at least degrees or a virucidal disinfectant.
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