1 3 Acids, Bases, and Salts in the Home

Name Class DateCHAPTER 913SECTIONAcids, Bases, and SaltsAcids, Bases, and Salts in the HomeKEY IDEASAs you read this section, keep these questions in mind:• Why do you add cleaning products to water?• What are some of the products in your home thatcontain acids, bases, or salts?Why Do You Add Cleaning Products to Water?Acids, bases, and salts are not just found in a sciencelaboratory. Many items in your home or school containacids, bases, and salts. These items include soaps, detergents,shampoos, antacids, vitamins, sodas, and juices.Cleaning products that contain salts are very useful.For example, if your hands are greasy after you eatfrench fries, you cannot clean them with just water. Thisis because water does not mix with oil. Instead, you needto wash your hands with soap. Soaps and other cleaningproducts help water mix with oily substances.SOAPSSoap is made of sodium or potassium ions and fattyacids. Fatty acids are molecules made of long chainsof hydrogen and carbon atoms. The fatty acids mixwell with oil. The sodium or potassium ions mix wellwith water. Because of its two different parts, soap candissolve in both oil and water.Soap forms a mixture of oil and water called an emulsion.Recall that in an emulsion, liquids that normally donot mix are spread throughout each other. Soap acts asan emulsifier by surrounding drops of oil. When you rinsethe soap away, the water also washes away the oil, leavingyour skin clean.READING TOOLBOXUnderline As you read thissection, use colored pens orpencils to underline examplesof acids, bases, and salt.Use red for acids, blue forbases, and purple for salts.READING CHECK1. Describe What is thebasic structure of soap? Howdoes this structure help soapclean?Copyright © by Holt, Rinehart and Winston. All rights reserved.Interactive Reader 197 Acids, Bases, and Salts

Name Class DateSECTION 3Acids, Bases, and Salts in the Home continuedHow Does Soap Work?Nonpolar tail1 Soap is an ionic compound. Itsnegative ion is made of long fattyacid chains. Its positive ion is asodium or potassium ion.Polar head2. Identify What are thepositive and negative ions insoap?2 Soap acts as an emulsifier.It surrounds droplets ofoily dirt. The fatty acids mixwith the oil. The positiveion mixes with the water.3 The droplets of oil anddirt surrounded by soapstay suspended in water.Because the oily dirt issuspended in water, youcan rinse it away.3. Explain Why can soapmix with both oil and water?READING CHECK4. Explain How does soapscum form?DETERGENTHave you ever noticed a greasy ring around the bathtubafter a bath? Soap is good for cleaning many things.However, soap does not work well in hard water. Hardwater contains dissolved ions, such as Mg 2+ , Ca 2+ , andFe 3+ . The fatty acids in soap can combine with these ionsto form soap scum. Soap scum is a salt that is insolublein water.Like soaps, detergents are salts made of ions andfatty acids. They also emulsify oils and dissolve in water.However, the ends of the fatty chains in detergents aredifferent from those in soaps. Because of these differences,detergents do not form insoluble salts in hardwater. Therefore, detergents do not form soap scum. Forthis reason, detergents are used in most shampoos, liquidhand cleansers, and body washes.The source of detergents is also different from soaps.Soaps are made from animal fats or plant oils. Detergentsare made from petroleum products.Copyright © by Holt, Rinehart and Winston. All rights reserved.Interactive Reader 198 Acids, Bases, and Salts

Name Class DateSECTION 3Acids, Bases, and Salts in the Home continuedBLEACHA disinfectant is a substance that kills viruses andbacteria. Bleach is an example of a disinfectant madeof a base, sodium hypochlorite, NaOCl. Bleach can alsoremove colors and stains from fabrics.Although bleach can be very useful, it can also be dangerous.If you mix bleach with an acid, poisonous gasesform. You should never mix bleach with an acid suchas vinegar. In addition, you should not mix bleach withammonia because a toxic gas will form.AMMONIAAmmonia solutions are also good cleansers. Recallthat ammonia is a weak base. When it is dissolved inwater, it does not ionize completely. The concentration ofhydroxide ions in an ammonia solution is low. However,an ammonia solution contains enough hydroxide ions toremove fingerprints and oily smears from windows. Manyammonia cleaners sold in stores are a combination ofalcohols, detergents, and other cleaning agents.READING CHECK5. Explain Why should younot mix bleach with acids orammonia?What Are Some Examples of Acids, Bases,and Salts in Your Home?In addition to household cleaners, many other itemsin your home contain acids, bases, or salts. These itemsinclude many of the health, beauty, and food productsyou may use every day.HEALTH AND BEAUTY PRODUCTSHave you ever used an antacid when you had a stomachache? An antacid is a weak base that neutralizesexcess stomach acid that can make you feel sick. Someother health and beauty products that contain acids,bases, or salts are listed below.• Toothpastes and contact lens solution contain salts.• Shaving cream and face lotion contain weak acids.• Makeup and hair products may contain acids or bases.READING CHECK6. Explain How can anantacid make you feel betterwhen you have a stomachache?Copyright © by Holt, Rinehart and Winston. All rights reserved.Interactive Reader 199 Acids, Bases, and Salts

Name Class DateSECTION 3Acids, Bases, and Salts in the Home continued7. Infer Why do you thinkmost shampoos are made ofdetergents rather than soaps?READING CHECK8. Define What is anantioxidant?SHAMPOOSMost shampoos are made of detergents. Peopleuse shampoos to remove dirt and oil from their hair.However, shampoos are not meant to remove all the oilfrom hair. Some oil is needed to make your hair shinyand to keep it from becoming dry and brittle. Shampoosare typically pH balanced. That is, they are made to bein a specific pH range. Hair looks its best when it is at aslightly acidic pH.ANTIOXIDANTSHave you ever noticed that a piece of apple will turnbrown after a short time? Many cut fruits turn brownwhen they are exposed to air. They turn brown as moleculesin the fruit react with oxygen.If you rub a piece of apple with lemon juice, it willlook fresher longer. Why? The citric acid in lemon juiceacts as an antioxidant. An antioxidant prevents oxygenfrom reacting with other molecules. Lemon juice preventsoxygen from reacting with molecules in the pieceof apple.Vitamin C, or ascorbic acid, is another antioxidant.Citric acid and vitamin C prevent the enzyme in the oxidationreaction from working. Vitamin C also reacts withoxygen molecules before the oxygen can react with themolecules in the fruit.FOOD PRODUCTSSome acids are useful in cooking because they canchange proteins in foods. For example, acids such as vinegaror citric acid can unravel the proteins in meats. Thismakes meat more tender. Healthy bacteria produce lacticacid as they use the sugar lactose in milk for energy.Lactic acid changes the milk protein casein into a thickgel. This gel is an important ingredient in yogurt.Copyright © by Holt, Rinehart and Winston. All rights reserved.Interactive Reader 200 Acids, Bases, and Salts

Name Class DateSECTION 3Acids, Bases, and Salts in the Home continuedBaking powder releasesCO 2during baking. TheCO 2in the batter causesbiscuits to rise.9. Identify What is the roleof baking powder in makingbiscuits rise?In addition to table salt, people use other salts for baking.For example, baking soda, or sodium hydrogen carbonate,forms carbon dioxide gas at high temperatures.Baking soda is added to cookies to make them rise asthey bake.Like baking soda, baking powder is a salt that can beadded to some foods to make them rise. Baking powdercontains baking soda and an acidic substance. Whenmixed with water, these compounds react to produceCO 2. Carbon dioxide makes cake batter light and fluffyand helps biscuits rise.Investigate Choose a healthor beauty item you use everyday. Read the back label ofthe item and write down allthe ingredients. Researchthe ingredients to find out ifthey are acids, bases, or salts.Make a poster that describesyour findings and present itto the class.CLEANING PRODUCTSBases are also found in many cleaning products inthe kitchen. For example, many drain cleaners are madefrom bases. Strong bases such as sodium hydroxidebreak down grease and other food material that causeclogs in drains.Copyright © by Holt, Rinehart and Winston. All rights reserved.Interactive Reader 201 Acids, Bases, and Salts

Name Class DateSection 3 ReviewSECTION VOCABULARYantacid a weak base that neutralizes stomachacidbleach a chemical compound used to whitenor make lighter, such as hydrogen peroxide orsodium hypochloritedetergent a water-soluble cleaner that canemulsify dirt and oildisinfectant a chemical substance that killsharmful bacteria or virusessoap a substance that is used as a cleaner andthat dissolves in water1. Explain Why do soaps and other cleaning products clean better than water alone?2. Compare Identify one similarity between soaps and detergents. Identify twodifferences.3. Summarize Complete the Spider Map below to describe four common types ofcleaners. On the lines, indicate whether each is an acid, base, or salt, and giveexamples of products that contain each.SoapBleachCleaners1. Acid, bases, or salt?2. Some products they areused inDetergentAmmoniaCopyright © by Holt, Rinehart and Winston. All rights reserved.Interactive Reader 202 Acids, Bases, and Salts