FOCUS ON PHYSICAL SCIENCE (12)

Acids and Bases in Solution /…iÊ Ê`i> Aqueous solutions of acids and bases have characteristic properties and can be identified by their pH values Solutions LESSON 7.c, 9.e >ˆ˜Ê`i> Most of the substances you encounter daily are solutions 5.e, 9.a, 9.b, 9.e Acidic, Basic, and Neutral Solutions LESSON >ˆ˜Ê`i> The pH scale measures the acidity of a solution Now how did that h happen? appen? It took hundreds of years to form these strange rock towers that surround Mono Lake in California The knobs and spires of rock “grew” year by year as water from the landlocked lake evaporated This left behind the masses of rock that had been dissolved in its waters -Vˆi˜ViÊÊ+PVSOBM Write a brief paragraph on what you think these rocks are made from 376 Start-Up Activities Determining pH Make the following Foldable to show how to determine whether a solution is acidic, basic, or neutral Where’s that bubble? You encounter acids and bases every day Do acids and bases react with one another? Procedure STEP Fold a sheet of paper in half lengthwise Make the back edge about cm longer than the front edge Read and complete a lab safety form Measure 125 mL of distilled water into each of two beakers Add 10 g of baking powder to one beaker and 10 g of baking soda to the other STEP Fold into thirds Stir until dissolved Record your observations in your Science Journal Add 15 mL of vinegar to each beaker and record your observations Think About This STEP Unfold and cut along the folds of the top flap to make three flaps • Describe what you expected and what you observed • Check the ingredient list on the box of baking powder Is one ingredient common to both products? How does this explain your observations? STEP Label the flaps as shown 5.e -œṎœ˜Ã
Vˆ`à Visit ca8.msscience.com to: υ υ υ υ view explore Virtual Labs access content-related Web links take the Standards Check iÕÌÀ> >Ãià Interpreting As you read Lesson 2, record important information about acidic, basic, and neutral solutions Be sure to include examples 377 Get Ready to Read Make Connections ELA8: R 2.3 Learn It! Make connections between what you read and what you already know Connections can be based on personal experiences (text-to-self), what you have read before (text-to-text), or events in other places (text-to-world) As you read, ask connecting questions Are you reminded of a personal experience? Have you read about the topic before? Did you think of a person, a place, or an event in another part of the world? Practice It! Read the excerpt below and make connections to your own knowledge and experience Have you ever removed all the onions from your salad before eating it? In addition to magnetism, what are other properties of iron? Have you ever picked out your favorite nut from a bowl of mixed nuts? If so, you separated a component from a mixture Components of mixtures can be separated by taking advantage of the differences in their physical properties Iron has the property of magnetism, but sand does not A mixture of iron and sand can be separated by moving a magnet through the mixture The magnet picks up the iron from the mixture The sand remains behind —from page 386 How can you use the property of magnetism to sort recycling materials? Apply It! As you read this chapter, choose five words or phrases that make a connection to something you already know 378 Target Your Reading Use this to focus on the main ideas as you read the chapter Before you read the chapter, respond to the statements below on your worksheet or on a numbered sheet of paper • Write an A if you agree with the statement • Write a D if you disagree with the statement After you read the chapter, look back to this page to see if th tions wi c e n n o s, c Make ts, place n e v e e l b memora life in your e l p o e p nection, or n o c e h t er The bett kely you will e li the mor er rememb you’ve changed your mind about any of the statements • If any of your answers changed, explain why • Change any false statements into true statements • Use your revised statements as a study guide Before You Read A or D Statement After You Read A or D A substance can be an element or a mixture In a mixture, you can always see the different parts that make it up An alloy is a homogeneous mixture Water is an excellent solvent because its electrons are shared equally If a solution is unsaturated, you can dissolve more solute in it A neutral solution has a pH of Print a worksheet of this page at ca8.msscience.com Water is a product of a neutralization reaction You can determine the exact pH of a solution by using litmus paper Acids have pH values between and 14 10 pH can be measured accurately with a pH meter 379 LESSON Science Content Standards 7.c Students know substances can be classified by their properties, including their melting temperature, density, hardness, and thermal and electrical conductivity 9.e Construct appropriate graphs from data and develop quantitative statements about the relationships between variables Reading Guide What You’ll Learn ▼ Compare two types of mixtures ▼ Relate the solvent properties of water to its molecular structure Why It’s Important You will better understand acids and bases if you know how solutions differ from other types of mixtures Solutions >ˆ˜Ê`i> Most of the substances you encounter daily are solutions Real-World Reading Connection When you walk down the aisles in a supermarket, you can’t help but notice the variety of liquid products for sale These include household cleaners, shampoos, fruit drinks, soft drinks, vinegar, and rubbing alcohol What might these products have in common? What are the types of matter? Mono Lake is a salt lake located high in the Sierra Nevada, a mountain range in California What’s special about this lake is that its water is more than twice as salty as the ocean Mono Lake is an ancient lake with no outlet Streams flow into the lake, bringing with them dissolved salts and minerals Over the centuries, the amount of this dissolved matter has increased Figure shows some interesting formations called tufas (TOO faws) that line the lakeshore These are composed of limestone, or calcium carbonate, that was originally dissolved in the water and then settled out Figure Vocabulary substance mixture homogeneous mixture heterogeneous mixture solution solute solvent Review Vocabulary liquid: matter with a definite volume but no definite shape that can flow from one place to another (p 257) 380 Chapter • Acids and Bases in Solution These rock formations around Mono Lake in California form when the lake water can no longer contain all the salts and minerals that are dissolved in it Substances WORD ORIGIN The waters of Mono Lake contain only a small fraction of the different kinds of matter that exist on Earth Recall that matter has mass and takes up space Figure shows that matter can be separated into two categories—pure substances and mixtures A substance is matter that has the same composition and properties throughout Elements and compounds are substances Recall from Chapter that an element consists of only one kind of atom You are probably familiar with the elements calcium, carbon, and oxygen Compounds are composed of elements that are bound together by ionic or covalent bonds Some compounds you probably know of are water, sodium chloride, and calcium carbonate substance from Latin substantia; means being, essence, material Figure A substance can be a compound, such as sodium chloride, or an element, such as gold Name two types of mixtures BViiZg =VhbVhhVcYiV`ZhjeheVXZ HjWhiVcXZ 9Z[^c^iZXdbedh^i^dc B^mijgZh KVg^VWaZXdbedh^i^dc =dbd\ZcZdjh b^mijgZ :kZcanb^mZY :aZbZci DcZ`^cYd[Vidb 8dbedjcY IlddgbdgZ`^cYh d[Vidbh =ZiZgd\ZcZdjh b^mijgZ K^h^WaZeVgi^XaZh Lesson • Solutions 381 Figure The doorknob is a homogenous mixture of two elements Oc 8j 7gVhhi]gdj\] VbV\c^[^Zg 7gVhhVii]Z Vidb^XaVnZg Mixtures WORD ORIGIN What happens when you combine two or more substances? A mixture is a combination of two or more substances that can be separated by physical means Mixtures can contain elements, compounds, or a combination of both Each compound or element found in a mixture can be identified by its properties Your favorite soft drink is a mixture of water, sugar or another sweetener, flavorings, and carbon dioxide The sweet taste comes from the sugar, and the tartness comes from the carbon dioxide Compounds have definite compositions, but the composition of a mixture can vary What is the difference between a compound and a mixture? homogeneous from Greek homos (means same) and genos (means kind) heterogeneous from Greek heteros (means different) and genos (means kind) Figure When this granite rock formed, substances of different colors hardened into a solid mixture Homogeneous Mixtures Sometimes, you can tell that a sample of matter is a mixture because you can identify more than one substance Other times, it’s impossible to decide whether or not the sample is a mixture A homogeneous mixture is two or more substances that are evenly mixed on the atomic level, but the substances are not bonded together Figure shows how an object, such as a brass doorknob, appears through a magnifying lens to be made of one substance If you could see the atoms on the atomic level, however, you would notice that zinc and copper atoms are evenly mixed Brass is a homogeneous mixture A homogeneous mixture is also called a solution Heterogeneous Mixtures It is easy to tell that some things are mixtures by looking at them A salad is a mixture of lettuce, tomatoes, and other ingredients A mixture in which the substances are not evenly mixed is a heterogeneous mixture Notice the regions of different colors in the sample of granite in Figure The colors indicate that granite is made of more than one substance Granite is a heterogeneous mixture A bowl of vegetable soup and mixed nuts are examples of heterogeneous mixtures 382 Chapter • Acids and Bases in Solution LViZg 9g^c` eVgi^XaZh =dbd\ZcZdjh b^mijgZ Aqueous solutions of acids and bases have characteristic properties and can be identified by their pH values Lesson Solutions >ˆ˜Ê`i> Most of the substances you encounter daily are solutions 7.c, 9.e • • • • Matter is composed of substances and mixtures • Mixtures have variable compositions and can be separated by means of physical properties or physical changes • • Solutions are homogeneous mixtures • • Water is found on Earth in all three states of matter and is essential to all living organisms • The polar nature of the water molecule and its bent shape are responsible for water’s unique properties • Water forms aqueous solutions by dissolving ionic compounds and polar molecules • Solutions that contain ions can conduct an electric current • • Lesson Acidic, Basic, and Neutral Solutions >ˆ˜Ê`i> The pH scale measures the acidity of a solution • • • • Acidic solutions taste sour, neutralize bases, react with metals and calcium carbonate, and turn blue litmus paper red Basic solutions taste bitter, feel slippery, neutralize acids, and turn red litmus paper blue heterogeneous mixture (p 382) homogeneous mixture (p 382) mixture (p 382) solute (p 384) solution (p 383) solvent (p 384) substance (p 381) 5.e, 9.a, 9.b, 9.e • • • • • • acid (p 395) base (p 395) hydronium ion (p 395) indicator (p 403) pH (p 399) pH meter (p 404) Acids release hydrogen ions in aqueous solutions, forming hydronium ions, H3Oϩ Bases form hydroxide ions, OHϪ, in aqueous solutions • The pH scale ranges from below to above 14 and is used to measure the acidity of a solution • The pH of a neutral solution is • Acidic solutions have pH values less than Basic solutions have pH values greater than • The approximate pH of a solution can be determined using indicators and pH test strips • pH meters can measure the exact pH of a solution 412 Chapter • Standards Study Guide Download quizzes, key terms, and flash cards from ca8.msscience.com Interactive Tutor ca8.msscience.com Standards Review CHAPTER Linking Vocabulary and Main Ideas Use vocabulary terms from page 412 to complete this concept map Matter can be a substance which can be a(n) which can be a element homogeneous mixture can be a solvent made up of can be acids which produce which produce hydroxide ions Visit ca8.msscience.com for: υ υ υ Vocabulary PuzzleMaker Vocabulary eFlashcards Multilingual Glossary Using Vocabulary Describe the relationship between each pair of terms solute and solvent mixture and solution 10 heterogeneous mixture and homogeneous mixture 11 acid and base Match the correct vocabulary term to each definition below 13 a form of matter that has the same composition and properties throughout the sample 14 a compound that changes from one color to another within a particular pH range 15 an electronic instrument with an electrode that is sensitive to the hydronium ions in a solution 12 hydronium ion and pH Chapter • Standards Review 413 Standards Review CHAPTER Understanding Main Ideas What substance could you use to neutralize a solution with a pH of 1.5? A milk B vinegar C ammonia 5.e D water Choose the word or phrase that best answers the question Which is a solution? A pure water B raisin cookie dough C copper D vinegar 7.c The graph below is a solubility curve for sodium chloride, NaCl The figure below illustrates reaction of water molecules    HdajW^a^in\gVbheZg&%%\d[lViZg HdajW^a^in )-% ))% )%% (+% HjXgdhZhj\Vg ('% '-% ')% HdY^jbX]adg^YZ '%% &+% EdiVhh^jbX]adg^YZ &'% -% 8VaX^jbXVgWdcViZ )% % &% '% (% )% *% +% ,% -% % IZbeZgVijgZ8 What mass of NaCl is needed to form a saturated solution at 80°C? A 30 g B 35 g C 40 g 7.c D 80 g The pH of apricots is 4.5 What color would litmus paper turn if a drop of apricot juice were placed on it? A red B blue C purple 5.e D yellow 414 Chapter • Standards Review What process is shown in the diagram? A the formation of a hydroxide ion B the formation of a hydronium ion C neutralization D saturation 5.e What ions must be present in the greatest amount in a solution with a pH of 8.5? A hydrogen ions B oxygen ions C hydronium ions D hydroxide ions 5.e Which best describes a solution that has dissolved all the solute it can hold? A It is a saturated solution B It is an unsaturated solution C It is a concentrated solution 7.c D It is a dilute solution Which is NOT a property of a base? A turns red litmus blue B is slippery to feel and bitter to taste C reacts with metals to produce hydrogen D is an electrolyte 5.e Which chemical formula describes a hydronium ion? A H3O+ B OH− C H3O− 5.e D OH+ Standards Review ca8.msscience.com Standards Review CHAPTER Applying Science Cumulative Review 10 Make use of what you know about the concentrations of hydronium ions and hydroxide ions in a solution having a pH of and explain why 5.e the solution is neutral 16 Demonstrate how to balance the equation for the neutralization of sulfuric acid with the base sodium hydroxide: 5.b H2SO4 + NaOH ៮៬ Na2SO4 + H2O 11 Explain why an indicator might not change color when it is placed in an acidic or a basic 5.e solution 17 Classify bases as being usually ionic compounds or usually covalent compounds and give evidence 7.c for your answer 12 Design an experiment that will allow you to 7.c separate a mixture of sugar and sand 18 Decide whether neutralization is a chemical 5.e change 13 Draw a conclusion from the graph below about why soft drinks, which contain dissolved carbon dioxide, quickly go flat as they warm up to room 7.c temperature HdajW^a^in@\$A HdajW^a^ind[8D' ^cLViZgVi&Vib ,% +% *% )% (% '% &% % &% '% (% )% *% +% ,% IZbeZgVijgZ8 14 Predict Geologists have measured the pH of the water in Mono Lake to be 9.8 What will happen to the pH as water evaporates from the 5.e lake? 3CIENCE 15 Design and write a paragraph for an informational sign that could be placed at Mono Lake to explain to visitors how and why tufas form Applying Math Use the table below to answer questions 19–21 Difference in pH Power of 10 Decimal Form 101 10 102 100 103 1000 104 10,000 105 100,000 106 1,000,000 19 Find the difference in acidity between apple juice that has a pH of and lemon juice that has a pH of MA8: ALG 2.0 20 If tomato juice has a pH of and white bread has a pH of 6, find the difference in acidity MA8: ALG 2.0 21 Find the difference in acidity between normal rain that has a pH of 5.7 and acid rain that has a pH of 5.2 MA8: ALG 2.0 Chapter • Standards Review 415 CHAPTER Standards Assessment Use the graph below to answer questions and What is the symbol for the hydroxide ion? HdajW^a^in\gVbheZg&%%\d[lViZg A H3O + B OH_ C H 2O D H2O2 5.e The image below shows a mixture of sand and iron filings being separated HjXgdhZhj\Vg EdiVhh^jbX]adg^YZ &% '% (% )% *% +% ,% -% % IZbeZgVijgZ8 How does the solubility of sucrose change as the temperature increases? A It increases A density B It does not change B ductility C It decreases C magnetism D It fluctuates randomly 7.c Which statement is TRUE? B As water temperature increases, the solubility of potassium chloride decreases B They feel slippery C They are in many cleaning products D They taste bitter 7.c A Potassium chloride is more soluble in water than sucrose Which is a property of acidic solutions? A They taste sour )-% ))% )%% (+% ('% '-% ')% '%% &+% &'% -% )% % What physical property is used to separate the sand and iron? D malleability HdajW^a^in 5.e When iodine is dissolved in alcohol, what term is used to describe the alcohol? C Sucrose is more soluble in water than potassium chloride D Water temperature has no effect on the solu7.c bility of these two chemicals A alloy B solvent C mixture D solute 416 Chapter • Standards Assessment 7.c Standards Assessment ca8.msscience.com Standards Assessment 10 Which type of molecule is water? A polar CHAPTER What indicators could be used to produce a color change at both pH and pH 8? A cresol red and thymol blue B ionic B universal indicator and alizarin C nonpolar D precipitate C thymol blue and bromphenol blue 7.c D phenol red and bromcresol green A change of what property permits certain materials to act as indicators? 11 A acidity B No solids or gases are present as solutes in them C concentration D basicity 5.e C All are extremely concentrated D Water is the solvent in them Use the illustration below to answer questions and 10 ) * + , - 12 H+ 8gZhdagZY B H3O + I]nbdaWajZ C H3O – D OH– 13 7gdbXgZhda\gZZc 7gdbXgZhdaejgeaZ 7.c Which is the symbol for a hydronium ion? A 7gdbe]ZcdaWajZ 5.e A solution is prepared by adding 100 g of solid sodium hydroxide, NaOH, to 1,000 mL of water What is the solid NaOH called? A solution 6a^oVg^c 7gdbi]nbdaWajZ B solute E]ZcdagZY Jc^kZghVa^cY^XVidg C solvent D mixture 14 What characteristic aqueous solutions share? A They contain more than three solutes B color ' ( 8gnhiVak^daZi 5.e 7.c What indicator can be used at a pH of 7? The reaction between an acidic and basic solution is called A bromphenol blue A neutralization B bromcresol green B saturated C bromcresol purple C substance D phenol red 5.e D mixture Chapter • Standards Assessment 5.e 417 ... of the concentration of hydronium ions, H3Oϩ, in a solution The higher the concentration of hydronium ions, the more acidic the solution is The lower the concentration of hydronium ions, the... is greater than the concentration of hydronium ions In neutral solutions (pH ϭ 7), the hydronium ion and hydroxide ion concentrations are equal Which ion—hydroxide or hydronium—is present in the... Hydronium ions and hydroxide ions are present in any water solution As one ion increases, the other decreases The pH scale is related to the concentration of hydronium ions As the numbers on the