CHEM100 CSUN Chemistry Lab Making A Soap Experiment Report

timer Asked: Feb 17th, 2019
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Question Description

1.please read the experiment process first

2. We used Natural coconut oil for our experiment

3. after we added everything together, we use the 300℃ to boil it for one hour. and it became solid (white color) and smells good.

4.make sure that you include how not stirring fast enough consistently affected the process(we all spend a lot of time to do this during this experiment ).

Group Oil Used for Soap Smell of Soap Color of Soap Texture of Soap 1: Jada & Sammi & Tianyi 2: Emily & Molly Coconut No scent White Hard and crumbly Applesauce Grapeseed 3: Jake & Abby & Sam 4: Li & Jiahao 5: Ana & Charles Sunflower 6: Xuping & Xiyun Vegetable Olive Sesame Playdoh Faint sunflower oil Cucumber Faintly burning hair Cucumber Oil Emulsification Score 3 pH 12 Hard Water Test 3 5 10 5 White Mushy when touched, slimy, but smooth. Crumbly. 1 10 2 Off-white Hard 3 10 5 Dark yellow Super oily 2 11 2 Yellow Smooth, delicate. 5 12 1
Making Soap Terms:                   Carboxyl group (COOH) Carboxylate (COO-) Cis-/trans fat Detergent Emulsifier Emulsion Fat Fatty acid Glycerol Hard water Hydrophilic Hydrophobic Micelle Oil Saturated/unsaturated Soap Soap scum Triglycerides Figure 1. Believe it or not, this is Lake Erie - a fresh water lake. The green color comes from algae whose growth was promoted by high levels of phosphates from agricultural run-off and from laundry detergents. Many municipalities have banned phosphatecontaining detergents to prevent large algal blooms in their lakes and rivers. Introduction Not too very long ago if you wanted to wash your hair, take a bath, clean your clothes or wash some dirty dishes, you had only one choice for cleaning - lye soap. Many homes made their own lye soap from hog fat and lye (which was usually potassium hydroxide). Add some heat to the mixture, and lots of vigorous stirring and voilà, you had soap. Today, you will be making your own lye soap, not from hog fat but with some common oils used in the kitchen such as olive, canola and walnut oils. Could the chemical properties of the oil affect the soap’s color, fragrance, pH or texture? Before you try to answer that question, let’s look at the structure of a soap molecule and see how its structure gives it the ability to remove greasy stains with only water. Fats and Oils Soap molecules are made from fats or oils – both of which are triglycerides. A triglyceride is a molecule with three (tri means three) fatty acid molecules bonded to a three-carbon backbone molecule called glycerol. See Figure 3a. All fatty acids have two things in common: 1) a carboxyl group (-COOH) at one end which makes the molecule an acid, and 2) a long, unbranched chain with only C and H atoms. Figure 2 gives two examples of fatty acids. Almost all naturally occurring fatty acids have an even number of carbon atoms somewhere between 10 and 30 carbon atoms long. Ever wonder how fats and oils are different? Although fats and oils have very similar chemical properties, 1 Figure 2. Example of a saturated fatty acid with all single bonds between the carbon atoms (C-C) AND an unsaturated fatty acid with C=C double bonds (and kinks). The COOH ends of both molecules are hydrophilic (water-loving) but the chain of CH atoms is hydrophobic (water-fearing). fats such as butter or lard are solid at room temperature and come from animals while oils are liquid at room temperature and come from plants. The real chemical difference between them however, is the type of chemical bond between the C atoms in the fatty acid chain. In fats, the C atoms are always connected by a single covalent bond (C-C) and with two H atoms bonded to every carbon atom. Look at the saturated fatty acid in Figure 2 again. In contrast, oils which are liquid at room temperature have one or more carbon to carbon double bonds (C=C). Their fatty acids are called unsaturated and may have one double bond (monounsaturated) or more (polyunsaturated) but either way they are usually made by plants. The C=C double bonds in unsaturated fatty acids give the molecule “kinks” or bends which prevent the oil molecules from packing together as tightly. Because their fatty acid molecules are further apart, oils remain liquid at room temperature. Look at Figure 3c. Currently, nutrition labels must include the amounts per serving for saturated, monounsaturated and polyunsaturated fats. If the serving contains over one-half gram of fat, the label must also include the trans-fat content of the product. See Figure 4 for a brief explanation of trans-fats. Figure 3. The triglyceride in (a) has three saturated fatty acids in it (no C=C bond). Notice how the three fatty acids in (a) and (b) are linear, making it possible for them to pack tightly together and form a solid fat at room temperature. In contrast, the three unsaturated fatty acids in the oil in (c) all have double bonds (C=C) which introduce ‘kinks’ into the fatty acid chains so that the molecules can’t pack together tightly and are liquid at room temperature. C 2 Figure 4. In the cis- configuration for a fatty acid, both H atoms are on the same side of the C=C double bond. In the trans configuration, however, the two H atoms are on opposite sides of the chain. Naturally-occurring fatty acids are nearly always the cis- configuration. The trans- configuration is often produced when plant oils are commercially hydrogenated to make fats more solid at room temperature like margarine. Diets high in trans-fats have adverse effects on cholesterol levels and increase the risk of heart attack and stroke. Making Soap Mix a triglyceride (fat or oil) with a strong base like sodium hydroxide, heat and stir and you’ve got soap! What happens during the reaction? First, the bonds between the three fatty acids and the glycerol molecule are broken and an ionic bond then forms between the now exposed carboxylate (COO-) group of the fatty acid and the sodium ion (Na+) as shown in Figure 5. Commercially, the glycerol is often removed from the soap and used for other purposes but it’s a great moisturizer when left in the soap. Other common additions to handmade soaps include fragrances, essential oils, dyes, or additives such as uncooked oatmeal or pumice to give the soap texture. Bonds broken X3 Ionic bond Waste product Figure 4. Figure 5. When soap is made from a triglyceride and a base such as sodium hydroxide, the bonds between the fatty acids and the glycerol are broken. So how does the structure of a soap molecule help get that greasy stain out? You know water alone can't remove greasy stains because grease, oils and fat are hydrophobic (water-fearing) and just don’t mix with water. The cleansing power of soap molecules come from the fact that they are part hydrophilic and part hydrophobic as shown in Figure 6. In water, soap molecules form bubble structures called micelles with the hydrophilic (water-loving) ends of the soap molecules forming the outside edge of the micelle in contact with water. The hydrophobic (water-fearing) ends on the soap molecules cluster together inside the bubble (away from the water) and it’s here where small particles of grease can dissolve. Micelles are small enough that they (and their greasy load) can be washed down the drain together. Soaps Clean Because They’re Emulsifying Agents An emulsion is a stable mixture of two liquids which normally don’t mix - like oil and water or the oil and vinegar in some salad dressings. Shake an oil and vinegar mixture vigorously enough and you will have an emulsion. But let it sit for any length of time and the oil and vinegar will eventually separate into two separate layers unless an emulsifier is added. Emulsifiers are compounds which stabilize emulsions and typically have a hydrophilic end and a 3 hydrophobic end to their molecules - just like soap molecules. Common emulsions that use emulsifiers include ice cream, paint, mayonnaise and milk. Figure 6. When soap molecules are put in water, the hydrophilic ends of the soap molecules face the water molecules while the hydrophobic soap ends face inward and hang out together - as far away from the water as possible. This structure is called a micelle. Greasy bits dissolve in the hydrophobic interior of the micelle and are washed down the drain. How are Detergents an Improvement over Soaps? Detergent molecules, like soaps, are emulsifiers with a hydrophilic end and a long, hydrophobic end. Synthetic detergents are designed to overcome a couple of problems which soaps often have when mixed with hard water. Hard water has high concentrations of calcium, magnesium and/or iron cations which is no problem in itself. When lye soap meets hard water however, the sodium or potassium ions in the soap molecules are replaced by the Ca2+ or Mg2+ ions from the hard water that makes the soap molecule less soluble and produces soap scum. If you wash your hair with an old-fashioned lye soap and hard water, you’ll see a noticeable haziness on your hair which is soap scum. Soap scum is not in any way dangerous - just not a positive selling point. Synthetic detergents are less reactive with hard water and have better cleaning action due to changes in the hydrophilic end of the molecule. Often, the hydrophilic end of the soap molecule is replaced by a ring and a negatively charged sulfate, phosphate or sulfonate group. Figure 7 below is an example of an anionic detergent molecule - the major ingredient in shampoos. In contrast to shampoos, hair conditioners contain positively-charged detergent molecules to help more completely remove the negatively-charged detergent molecules from your hair. (Remember anions are negatively charged ions and cations are positively charged ions.) Figure 7. An example of a common detergent molecule (sodium dodecyl sulfate or SDS) which is found in many shampoos. The hydrophilic end of a detergent molecule doesn’t react with the divalent cations in hard water like soap – leaving your hair looking shinier and minus that hazy soap scum. 4 Protocol - Making Soaps from Plant Oils First, decide as a class who will use which oil so that all of the oils get tested for their properties as soaps. Table 1 lists some oils that you can use to make soap along with their fatty acid compositions. All oils are pure triglyceride and have 120 Calories per tablespoon. Oil Coconut Grapeseed Sunflower Olive Palm Sesame Vegetable Walnut Saturated 12.9 0.2 1.0 2.0 7.0 2.0 2.0 1.0 Amounts of Fats in Oils (g/Tablespoon) Monounsaturated Polyunsaturated 0.9 0.2 3.2 10.6 11.0 2.0 10.0 2.0 5.4 1.6 6.0 6.0 3.5 8.5 3.0 10.0 Total Fats (g) 14.0 14.0 14.0 14.0 14.0 14.0 14.0 14.0 Table 1. The amounts of saturated, monounsaturated and polyunsaturated fatty acids found in common types of cooking oils (g/Tablespoon). Notice that all or the oils have fourteen grams of total fat. MAKING YOUR SOAP: First, get your goggles, gloves and lab coat on as you will be working with some very strong and caustic bases today and we want you to be safe. 1. Measure 10 mLs of your oil into a clean 150 or 250 mL beaker using a graduated cylinder.  If your oil is solid at room temperature, microwave it 10-30 seconds until it’s liquid.  CAUTION: Do not use a flask in place of a beaker! The solution containing the very corrosive sodium hydroxide can boil very violently - enough to destroy a flask with its narrow opening. We do not want corrosive sodium hydroxide splashing on you or the bench! 2. Add 15 mL of 20% sodium hydroxide to the beaker. Set up a hotplate and a ring stand with a ring on it that is wide enough to go around your beaker as shown in Figure 8. The ring will keep the beaker from tipping over while you’re stirring. 3. Turn on the hotplate and heat the beaker while stirring vigorously with a long glass stirring rod. If you don’t stir the mixture enough, the two reactants may remain as separate layers, OR the soap may form a solid layer on the bottom of the beaker and char. Believe me, charred soap does not smell good! If the mixture is boiling too rapidly, turn down the temperature on your hotplate. Figure 8. The set-up for  CAUTIONS: Please do NOT lean your face over the beaker – just in making soap case some hot soap splatters up. Use a long, glass stirring rod so you can keep your hand as far away from the beaker as possible. This helps prevent hot oil from splattering onto your hands when the soap begins to foam. 5 4. As the mixture begins to foam and swell in the beaker, continue heating and stirring. As the foam dies down, the mixture may become quite syrupy but keep heating and stirring. When the mixture becomes so waxy that it sticks to, and builds up on the stirring rod, turn off the heat. The mixture should appear moist even though all of the water has been removed during heating. 5. Let your mixture cool slightly. If a waxy solid appears, congratulations you have just made soap! If the cooled mixture still appears like a syrupy liquid however, the reaction isn’t quite complete and you need to do more heating and stirring. 6. Make a solution of concentrated sodium chloride by dissolving ~18 g of NaCl in 60 mL of deionized water. This solution is ~30% NaCl. 7. Pour 20 mL of your 30% NaCl solution into the beaker containing the cooled soap. Try to break the soap into smaller pieces with your glass stirring rod. This sodium chloride rinse should remove any unreacted sodium hydroxide. 8. Set up a glass funnel in a ring to filter your soap as shown in Figure 9. Fold the filter paper for the funnel in half, then in half again. Place it in the glass funnel. Pour your soap-NaOH solution through the filter paper and collect the filtrate in a clean beaker. The filtrate is the liquid that drains through the filter paper and funnel. Discard the filtrate in the Hazardous Waste container in the fume hood. 9. Repeat the washing and filtering process of your soap two more times with the remaining sodium chloride solution to remove as much of the NaOH as possible using the same beakers. Place your soap on a piece of dry paper towel to remove the last traces of water. Figure 9. How to use a glass funnel to filter your soap sample. EVALUATING YOUR SOAP: 10. Describe the smell of your soap in Table 4 on the Data Sheet. EMULSIFICATION TEST: 11. Boil ~60 mLs of water using a hotplate. After the water is boiling, dissolve about ~1 g of your soap in the boiling water to create a ‘Boiled Soap Solution’. Compare your Boiled Soap Solution to a commercial detergent for their ability to emulsify a distilled water and oil mixture. Prepare test tubes 1 – 3 as shown in Table 2 using your Boiled Soap Solution - NOT THE SOAP SOLUTIONS BY THE LAB SINKS! Test Tube 1 – Control – No Soap 2 – Your Boiled Soap Solution 3 – Detergent Distilled Water (mL) 5.0 Vegetable Oil (drops) 7 Your Boiled Soap Solution (drops) 0 Detergent Solution (drops) 0 5.0 7 20 0 5.0 7 0 20 Table 2. Comparison of your soap’s ability versus a commercial detergent’s ability to emulsify a distilled water and oil mixture. 6 12. Cover the three test tubes with Parafilm and shake them vigorously. Then let them settle for five minutes. Using the scale on the next page, rate each test tube for emulsification. Look for the oil on top of the emulsion which you should clearly see in test tube 1. What about test tubes 2 & 3? Evaluate how well the oil was emulsified according to the Emulsification Scale. Keep these three tubes for the pH test. Record your results on the Data Sheet. Completely separate layers of oil & water visible after solution has settled. Oil completely dispersed in H2O not apparent as a separate layer. EMULSIFICATION NONE 0 1 2 3 4 COMPLETE 5 TESTING THE PH OF YOUR SOAP: 12. To test the pH of test tubes 1 - 3, tear off a small piece of pH paper (~1/4 inch long) and place it on a clean paper towel. Dip a clean glass stirring rod into the test tube and touch it to the pH paper. Compare the color that develops to the color guide for the pH paper and record the pH of the solution. Dispose of the contents of your test tubes in the Hazardous Waste and wash your test tubes with warm, soapy water.  Never dip the pH paper into the solution as the chemicals from the pH paper will contaminate your solution and could change its pH. HARD WATER TEST: 13. Compare your soap against a commercial detergent for its reaction in hard water. Prepare test tubes 4 – 6 in Table 3. Cover each of the test tubes with Parafilm and shake them vigorously, then compare the amount of white, gelatinous precipitate (aka soap scum) in the tubes on a scale from 0 (no scum) to 5 (lots of scum). Record your data on the Data Sheet.  Bubbles do not count as soap scum! Test Tube Hard Water (mL) Your Boiled Soap Solution (drops) Detergent Solution (drops) 4 – Control – No Soap 5.0 0 0 5 – Soap in Hard H2O 5.0 20 0 6 – Detergent in Distilled H2O 5.0 0 20 Table 3. Comparison of your soap to a commercial detergent for their reaction to hard water. 14. Press your remaining soap into a block and evaluate it for the following properties on your Data Sheet: color, consistency (hard & waxy, soft & crumbly) and smell. Write your data on the whiteboard too. Wash your hands with a small piece of your soap and describe how it feels. (NOTE: if the pH of your soap is greater than 11, wash quickly and rinse with lots of water.) 7 15. Leave the ring stand, ring and hot plate set up for the next lab section. If you haven’t already done so, thoroughly clean your test tubes and any glassware which you used with warm, soapy water. Then dry them and return them to your tub.  IF your lab is the last one of the week, please remove the ring from the ring stand and return both to their drawer/cupboard. 16. Display your soap for your classmates to see, smell and touch. Include the name of the oil you used to make your soap. You’ll need the data from your classmates about their soaps for the post-lab questions. 8 Data Sheet – 4 pts Name __________________________ Oil/Fat Used to Make Soap ___________________________ Describe the characteristics of your soap: o Color: o Consistency/texture o Smell: Does it have the same odor as the starting oil? o What it felt like to wash my hands with my soap o The long description: o One word description: Oil Used for Soap Smell of Soap Color of Soap Texture/ Consistency Oil Emulsification Score pH Hard Water Test Table 4. Class Results for different oils used to make soap. Oil Emulsification Score pH Hard Water Rxn Score Control Your Soap Commercial Detergent Table 5. Comparison of your soap vs. a commercial detergent for: 1) its ability to emulsify an oil and water mixture; 2) pH; and 3) reaction in hard water. 9
Data Sheet – 4 pts Name __________________________ Oil/Fat Used to Make Soap ___________________________ Describe the characteristics of your soap: o Color: white o Consistency/texture o Smell: Does it have the same odor as the starting oil? No, it smells different o What it felt like to wash my hands with my soap o The long description: o One word description: Oil Used for Soap Color pH Texture/Consistency Smell Oil Emulsification Score Hard Water Test Table 4. Class Results for different oils used to make soap. Oil Emulsification Score pH Hard Water Rxn Score Control Your Soap Commercial Detergent Table 5. Comparison of your soap vs. a commercial detergent for: 1) its ability to emulsify an oil and water mixture; 2) pH; and 3) reaction in hard water. 1 Making Soap Post Lab Questions – 16 pts Attach Your Data Sheet - 4 pts Name _____________________ 1. The fatty acid below is (SATURATED/MONOUNSATURATED/POLYUNSATURATED). Circle the hydrophilic part of the molecule, and underline the hydrophobic part of the molecule. 2 pts 2. Hard water has a high concentration of calcium and magnesium ions and occurs naturally in some parts of the country. Explain what happens chemically when: 1) lye soap meets hard water, and 2) synthetic detergents mix with hard water. 3 pts 3. Why should fragrance molecules be added only after the soap has been made and not added with the NaOH? 2 pt 4. Many environmental advocacy groups recommend that consumers avoid cleaning products that contain phosphorus and some states have an outright ban on phosphate-containing detergents. These laws were enacted after studies showed a high correlation between high phosphate concentrations in lakes and rivers and the process of eutrophication. o How do phosphates improve the action of detergents and soaps? 3 pts o What is eutrophication? What is the connection between eutrophication and high phosphate concentrations in detergents? 4 pts 5. Does the degree of unsaturation of the fatty acids in the oil affect the color, consistency, smell, pH, or reaction of the soap with hard water? Explain your answer using the class data for the different oils used to make soaps. 2 pts I have neither given nor received unauthorized help on this assignment. (Your Signature) 2 3

Tutor Answer

School: Rice University



When soap meets hard water, the Na+ and K+ ions in the soap molecule are replaced by Ca2+
and Mg+2 ions in the hard water and makes a precipitate called soap scum. This make soap molecules
less dissolve in the water.
When synthetic detergent mix with water, the detergent molecules are less reactive with hard...

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Good stuff. Would use again.

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