<ul><li>Think about pure water.  No matter what you do to it physically—freeze it, boil it, stir it, or strain it—it still...
<ul><li>Recall that atoms are the basic building blocks of matter.  </li></ul>Atoms and Elements
 
<ul><li>A  substance  is matter that has the same fixed composition and properties.  It can’t be broken down into simpler ...
 
<ul><li>An  element  is an example of a pure substance; it cannot be broken down into simpler substances.  </li></ul><ul><...
<ul><li>Water is not an  element .  It is an example of a  compound  which is made of two or more elements that are chemic...
<ul><li>Mixtures  are combinations of substances that are not bonded together and can be separated by physical processes. ...
<ul><li>Unlike compounds, mixtures do not always contain the same proportions of the substances that they are composed of....
Mixtures <ul><li>Lemonade is a mixture that can be strong tasting or weak tasting, depending on the amounts of water and l...
<ul><li>A type of  mixture  where the substances are not mixed evenly is called a  heterogeneous   (he tuh ruh JEE nee us)...
Heterogeneous Mixtures <ul><li>The substances in a  heterogeneous   mixture  are usually easy to tell apart, like the seed...
<ul><li>A  homogeneous mixture  contains two or more substances that are evenly mixed on a molecular level but still are n...
<ul><li>The substance that dissolves—or seems to disappear—is called the  solute . </li></ul><ul><li>The substance that di...
How Solutions Form <ul><li>In a hummingbird feeder  solution , the  solute  is the sugar and the  solvent  is water.  </li...
<ul><li>Under certain conditions, a  solute  can come back out of its  solution  and form a solid.  </li></ul><ul><li>This...
<ul><li>When some  solutions  are mixed, a chemical reaction occurs, forming a solid.  This solid is called a  precipitate...
<ul><li>Stalactites  and  stalagmites  in caves are formed from  solutions. </li></ul><ul><li>First, minerals dissolve in ...
<ul><li>When drops of the  solution  evaporate from the roof of the cave, the minerals are left behind.  </li></ul><ul><li...
Forming Solids from Solutions <ul><li>When drops of the  solution  fall onto the floor of the cave and evaporate, they for...
Types of Solutions <ul><li>Solutions  can be made up of different combinations of solids, liquids, and gases. </li></ul>
 
<ul><li>You’ve already learned about liquid-solid  solutions  such as sugar water and salt water.  </li></ul><ul><li>When ...
<ul><li>Carbonated beverages are liquid-gas  solutions —carbon dioxide is the gaseous  solute , and water is the liquid so...
<ul><li>In a liquid-liquid  solution , both the solvent and the  solute  are liquids.  </li></ul><ul><li>Vinegar, which yo...
<ul><li>In  gaseous solutions , a smaller amount of one gas is dissolved in a larger amount of another gas.  </li></ul><ul...
<ul><li>In  solid solutions , the  solvent  is a solid.  </li></ul><ul><li>The  solute  can be a solid, liquid, or gas.  <...
<ul><li>A solid-solid  solution  made from two or more  metals  is called an  alloy .  </li></ul>Solid Solutions <ul><li>B...
Water—The Universal Solvent <ul><li>A  solution  in which water is the  solvent  is called an  aqueous   (A kwee us)  solu...
Molecular  Compounds <ul><li>When certain atoms form  compounds , they share electrons. Sharing electrons is called  coval...
Molecular Compounds <ul><li>If a  molecule  has an even distribution of electrons it is called  nonpolar .  </li></ul><ul>...
Ionic  Bonds <ul><li>Atoms with a charge are called  ions .  </li></ul><ul><li>Bonds between  ions  that are formed by the...
How Water Dissolves Ionic Compounds <ul><li>Because water  molecules  are  polar , they attract  positive  and  negative i...
How Water Dissolves Ionic Compounds
How Water Dissolves Ionic Compounds <ul><li>The more negative part of a water molecule—where the oxygen atom is—attracts  ...
How Water Dissolves Molecular Compounds <ul><li>Water does dissolve  molecular   compounds , such as sugar, although it do...
What will dissolve? <ul><li>When you stir a spoonful of sugar into iced tea, all of the sugar  dissolves  but none of the ...
Like Dissolves Like <ul><li>When trying to predict which  solvents  can  dissolve  which  solutes , chemists use the rule ...
Like Dissolves Like <ul><li>On the other hand, if a  solvent  and a solute are not similar, the solute won’t dissolve.  </...
How much will dissolve? <ul><li>Solubility   (sahl yuh BIH luh tee) is a measurement that describes how much  solute disso...
Solubility in Liquid-Solid Solutions <ul><li>The  solubility  of many  solutes  changes if you change the  temperature of ...
<ul><li>This graph shows how the  temperature  of the  solvent  affects the  solubility  of some  solutes . </li></ul>
Solubility in Liquid-Gas Solutions <ul><li>Unlike  liquid-solid solutions , an increase in temperature decreases the  solu...
Saturated Solutions <ul><li>A  solution  that contains all of the  solute  that it can hold under the given conditions is ...
Saturated Solutions <ul><li>A  hot solvent  usually can hold more  solute  than a  cool solvent  can.  </li></ul><ul><li>I...
Rate of Dissolving <ul><li>Some  solutes dissolve  quickly, but others take a long time to  dissolve .  </li></ul><ul><li>...
Rate of Dissolving <ul><li>These methods increase the rate at which the surfaces of the  solute  come into contact with th...
Concentration <ul><li>The  concentration  of a solution tells you how much  solute  is present compared to the amount of  ...
Measuring  Concentrations <ul><li>One way of giving the exact  concentration  is to state the percentage of the volume of ...
Measuring Concentrations <ul><li>Labels on fruit drinks show their  concentration .  </li></ul><ul><li>Another way to desc...
Effects of Solute Particles <ul><li>The effect that a solute has on the freezing or boiling point of a solvent depends on ...
Effects of Solute Particles <ul><li>Adding a solute such as sodium chloride to this solvent changes the way the molecules ...
Acids <ul><li>Acids  are substances that release positively charged  hydrogen ions, H + ,  in the water. </li></ul><ul><li...
Acids <ul><li>The  hydrogen ion  then combines with a water molecule to form a  hydronium ion .  </li></ul><ul><li>Hydroni...
 
Properties of Acidic Solutions <ul><li>Sour taste  is one of the  properties of acidic solutions.  </li></ul><ul><li>Anoth...
Uses of Acids <ul><li>Vinegar , which is used in salad dressing, contains  acetic acid .  </li></ul><ul><li>Lemons, limes,...
Uses of Acids <ul><li>Your body needs  ascorbic acid , which is  vitamin C . </li></ul><ul><li>Sulfuric acid  is used in t...
Uses of Acids <ul><li>Acids  often are used in batteries because their  solutions conduct electricity . </li></ul><ul><li>...
Acid in the Environment <ul><li>Carbonic acid  plays a key role in the formation of caves and of  stalactites  and  stalag...
Bases <ul><li>Bases  are substances that can accept  hydrogen ions .  </li></ul><ul><li>When  bases  dissolve in water, so...
Bases <ul><li>A hydrogen atom in the water molecule leaves behind the other hydrogen atom and oxygen atom.  </li></ul><ul>...
Properties of Basic Solutions <ul><li>Basic solutions   feel slippery .  </li></ul><ul><li>Bases also taste bitter .  </li...
Uses of Bases <ul><li>Bases  give soaps, ammonia, and many other cleaning products some of their useful properties.  </li>...
Uses of Bases <ul><li>Chalk and oven cleaner are examples of familiar products that contain bases. </li></ul><ul><li>Your ...
Click box to view movie.
What is pH? <ul><li>pH   is a  measure  of how  acidic or basic  a solution is.  </li></ul><ul><li>The  pH scale  ranges f...
pH Scale <ul><li>A  change of 1 pH  unit represents a  tenfold change  in the  acidity  of the solution.  </li></ul><ul><l...
Strengths of Acids and Bases <ul><li>The difference between food acids and the acids that can burn you is that they have d...
Strengths of Acids and Bases <ul><li>In the same concentration, a strong acid—like hydrochloric acid—forms more hydronium ...
Strengths of Acids and Bases <ul><li>More  hydronium ions  means the  strong-acid solutions  has a  lower pH  than the  we...
Strengths of Acids and Bases <ul><li>The  strength of a base  is related to how easily the base  separates into ions , or ...
Indicators <ul><li>Indicators   are compounds that react with acidic and basic solutions and produce certain colors, depen...
Neutralization <ul><li>Heartburn or stomach discomfort is caused by  excess hydrochloric acid  in the stomach.  </li></ul>...
How does neutralization occur? <ul><li>Recall that every water molecule contains  two hydrogen atoms  and  one oxygen   at...
 
How does neutralization occur? <ul><li>Equal numbers of hydronium ions from the acidic solution and hydroxide ions from th...
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Elements Compounds And Mixtures

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Elements Compounds And Mixtures

  1. 1. <ul><li>Think about pure water. No matter what you do to it physically—freeze it, boil it, stir it, or strain it—it still is water. </li></ul><ul><li>On the other hand, if you boil salt water, the water turns to gas and leaves the salt behind. </li></ul><ul><li>How does chemistry explain these differences? </li></ul>Substances What is a solution?
  2. 2. <ul><li>Recall that atoms are the basic building blocks of matter. </li></ul>Atoms and Elements
  3. 4. <ul><li>A substance is matter that has the same fixed composition and properties. It can’t be broken down into simpler parts by ordinary physical processes, such as boiling, grinding, or filtering. </li></ul><ul><li>Only a chemical process can change a substance into one or more new substances. </li></ul>Atoms and Elements
  4. 6. <ul><li>An element is an example of a pure substance; it cannot be broken down into simpler substances. </li></ul><ul><li>The number of protons in an element , like oxygen, are fixed—it cannot change unless the element changes. </li></ul>Atoms and Elements
  5. 7. <ul><li>Water is not an element . It is an example of a compound which is made of two or more elements that are chemically combined. </li></ul><ul><li>Compounds also have fixed compositions. </li></ul>Compounds <ul><li>The ratio of the atoms in a compound is always the same. </li></ul>
  6. 8. <ul><li>Mixtures are combinations of substances that are not bonded together and can be separated by physical processes. </li></ul>Mixtures
  7. 9. <ul><li>Unlike compounds, mixtures do not always contain the same proportions of the substances that they are composed of. </li></ul>Mixtures
  8. 10. Mixtures <ul><li>Lemonade is a mixture that can be strong tasting or weak tasting, depending on the amounts of water and lemon juice that are added. </li></ul>
  9. 11. <ul><li>A type of mixture where the substances are not mixed evenly is called a heterogeneous (he tuh ruh JEE nee us) mixture . </li></ul><ul><li>The different areas of a heterogeneous mixture have different compositions. </li></ul>Heterogeneous Mixtures
  10. 12. Heterogeneous Mixtures <ul><li>The substances in a heterogeneous mixture are usually easy to tell apart, like the seeds from the fruit of a watermelon. </li></ul>
  11. 13. <ul><li>A homogeneous mixture contains two or more substances that are evenly mixed on a molecular level but still are not bonded together. </li></ul><ul><li>Another name for a homogeneous mixture is a solution . </li></ul>Homogeneous Mixtures
  12. 14. <ul><li>The substance that dissolves—or seems to disappear—is called the solute . </li></ul><ul><li>The substance that dissolves the solute is called the solvent . </li></ul>How Solutions Form
  13. 15. How Solutions Form <ul><li>In a hummingbird feeder solution , the solute is the sugar and the solvent is water. </li></ul>
  14. 16. <ul><li>Under certain conditions, a solute can come back out of its solution and form a solid. </li></ul><ul><li>This process is called crystallization . </li></ul>Forming Solids from Solutions <ul><li>Crystallization is the result of a physical change. </li></ul>
  15. 17. <ul><li>When some solutions are mixed, a chemical reaction occurs, forming a solid. This solid is called a precipitate (prih SIH puh tayt). </li></ul><ul><li>A precipitate is the result of a chemical change. </li></ul>Forming Solids from Solutions
  16. 18. <ul><li>Stalactites and stalagmites in caves are formed from solutions. </li></ul><ul><li>First, minerals dissolve in water as it flows through rocks at the top of the cave. </li></ul>Forming Solids from Solutions <ul><li>This solution of water and dissolved minerals drips from the ceiling of the cave. </li></ul>
  17. 19. <ul><li>When drops of the solution evaporate from the roof of the cave, the minerals are left behind. </li></ul><ul><li>They create the hanging rock formations called stalactites . </li></ul>Forming Solids from Solutions Stalactite
  18. 20. Forming Solids from Solutions <ul><li>When drops of the solution fall onto the floor of the cave and evaporate, they form stalagmites . </li></ul>Stalagmite
  19. 21. Types of Solutions <ul><li>Solutions can be made up of different combinations of solids, liquids, and gases. </li></ul>
  20. 23. <ul><li>You’ve already learned about liquid-solid solutions such as sugar water and salt water. </li></ul><ul><li>When discussing solutions , the state of the solvent usually determines the state of the solution . </li></ul>Liquid Solutions
  21. 24. <ul><li>Carbonated beverages are liquid-gas solutions —carbon dioxide is the gaseous solute , and water is the liquid solvent. </li></ul><ul><li>The carbon dioxide gas gives the beverage its fizz and some of its tartness. </li></ul>Liquid-Gas Solutions
  22. 25. <ul><li>In a liquid-liquid solution , both the solvent and the solute are liquids. </li></ul><ul><li>Vinegar, which you might use to make salad dressing, is a liquid-liquid solution made of 95 percent water ( the solvent ) and 5 percent acetic acid ( the solute ). </li></ul>Liquid-Liquid Solutions
  23. 26. <ul><li>In gaseous solutions , a smaller amount of one gas is dissolved in a larger amount of another gas. </li></ul><ul><li>This is called a gas-gas solution because both the solvent and solute are gases. </li></ul>Gaseous Solutions <ul><li>The air you breathe is a gaseous solution . </li></ul>
  24. 27. <ul><li>In solid solutions , the solvent is a solid. </li></ul><ul><li>The solute can be a solid, liquid, or gas. </li></ul>Solid Solutions <ul><li>The most common solid solutions are solid-solid solutions—ones in which the solvent and the solute are solids. </li></ul>
  25. 28. <ul><li>A solid-solid solution made from two or more metals is called an alloy . </li></ul>Solid Solutions <ul><li>Brass is a solid solution made of copper and zinc. </li></ul>
  26. 29. Water—The Universal Solvent <ul><li>A solution in which water is the solvent is called an aqueous (A kwee us) solution . </li></ul><ul><li>Because water can dissolve so many different solutes , chemists often call it the universal solvent . </li></ul>
  27. 30. Molecular Compounds <ul><li>When certain atoms form compounds , they share electrons. Sharing electrons is called covalent bonding . </li></ul><ul><li>Compounds that contain covalent bonds are called molecular compounds , or molecules . </li></ul>
  28. 31. Molecular Compounds <ul><li>If a molecule has an even distribution of electrons it is called nonpolar . </li></ul><ul><li>In a water molecule , the electrons spend more time around the oxygen atom than the hydrogen atoms. </li></ul><ul><li>Such a molecule is polar . </li></ul>
  29. 32. Ionic Bonds <ul><li>Atoms with a charge are called ions . </li></ul><ul><li>Bonds between ions that are formed by the transfer of electrons are called ionic bonds , and the compound that is formed is called an ionic compound . </li></ul><ul><li>Table salt is an ionic compound that is made of sodium ions and chloride ions . </li></ul>
  30. 33. How Water Dissolves Ionic Compounds <ul><li>Because water molecules are polar , they attract positive and negative ions . </li></ul><ul><li>The more positive part of a water molecule—where the hydrogen atoms are—is attracted to negatively charged ions. </li></ul>
  31. 34. How Water Dissolves Ionic Compounds
  32. 35. How Water Dissolves Ionic Compounds <ul><li>The more negative part of a water molecule—where the oxygen atom is—attracts positive ions . </li></ul><ul><li>When an ionic compound is mixed with water, the different ions of the compound are pulled apart by the water molecules. </li></ul>
  33. 36. How Water Dissolves Molecular Compounds <ul><li>Water does dissolve molecular compounds , such as sugar, although it doesn’t break each sugar molecule apart. </li></ul><ul><li>Water simply moves between different molecules of sugar, separating them. </li></ul>
  34. 37. What will dissolve? <ul><li>When you stir a spoonful of sugar into iced tea, all of the sugar dissolves but none of the metal in the spoon does. </li></ul><ul><li>A substance that dissolves in another is said to be soluble in that substance. </li></ul><ul><li>You would say that the sugar is soluble in water but the metal of the spoon is insoluble in water. </li></ul>
  35. 38. Like Dissolves Like <ul><li>When trying to predict which solvents can dissolve which solutes , chemists use the rule of “ like dissolves like .” </li></ul><ul><li>Polar solvents dissolve polar solutes and nonpolar solvents dissolve nonpolar solutes. </li></ul>
  36. 39. Like Dissolves Like <ul><li>On the other hand, if a solvent and a solute are not similar, the solute won’t dissolve. </li></ul><ul><li>For example, oil and water do not mix. </li></ul><ul><li>Oil molecules are nonpola r, so polar water molecules are not attracted to them. </li></ul>
  37. 40. How much will dissolve? <ul><li>Solubility (sahl yuh BIH luh tee) is a measurement that describes how much solute dissolves in a given amount of solvent . </li></ul><ul><li>The solubility of a material has been described as the amount of the material that can dissolve in 100 g of solvent at a given temperature. </li></ul><ul><li>When a substance has an extremely low solubility , it usually is considered insoluble . </li></ul>
  38. 41. Solubility in Liquid-Solid Solutions <ul><li>The solubility of many solutes changes if you change the temperature of the solvent. </li></ul><ul><li>For example, if you heat water, not only does the sugar dissolve at a faster rate , but more sugar can dissolve in it . </li></ul>
  39. 42. <ul><li>This graph shows how the temperature of the solvent affects the solubility of some solutes . </li></ul>
  40. 43. Solubility in Liquid-Gas Solutions <ul><li>Unlike liquid-solid solutions , an increase in temperature decreases the solubility of a gas in a liquid-gas solution. </li></ul><ul><li>You might notice this if you have ever opened a warm carbonated beverage and it bubbled up out of control while a chilled one barely fizzed. </li></ul><ul><li>Carbon dioxide is less soluble in a warm solution . </li></ul>
  41. 44. Saturated Solutions <ul><li>A solution that contains all of the solute that it can hold under the given conditions is called a saturated solution. </li></ul><ul><li>If a solution is a liquid-solid solution , the extra solute that is added will settle to the bottom of the container. </li></ul><ul><li>It’s possible to make solutions that have less solute than they would need to become saturated . Such solutions are unsaturated . </li></ul>
  42. 45. Saturated Solutions <ul><li>A hot solvent usually can hold more solute than a cool solvent can. </li></ul><ul><li>If a saturated solution is cooled slowly, sometimes the excess solute remains dissolved for a period of time. </li></ul><ul><li>Such a solution is said to be supersaturated , because it contains more than the normal amount of solute . </li></ul>
  43. 46. Rate of Dissolving <ul><li>Some solutes dissolve quickly, but others take a long time to dissolve . </li></ul><ul><li>A solute dissolves faster when the solution is stirred or shaken or when the temperature of the solution is increased. </li></ul>
  44. 47. Rate of Dissolving <ul><li>These methods increase the rate at which the surfaces of the solute come into contact with the solvent . </li></ul>
  45. 48. Concentration <ul><li>The concentration of a solution tells you how much solute is present compared to the amount of solvent . </li></ul><ul><li>You can give a simple description of a solution’s concentration by calling it either concentrated or dilute . </li></ul><ul><li>A concentrated solution has more solute per given amount of solvent than a dilute solution . </li></ul>
  46. 49. Measuring Concentrations <ul><li>One way of giving the exact concentration is to state the percentage of the volume of the solution that is made up of solute . </li></ul>
  47. 50. Measuring Concentrations <ul><li>Labels on fruit drinks show their concentration . </li></ul><ul><li>Another way to describe the concentration of a solution is to give a percentage of the total mass that is made up of solute. </li></ul>
  48. 51. Effects of Solute Particles <ul><li>The effect that a solute has on the freezing or boiling point of a solvent depends on the number of solute particles . </li></ul><ul><li>When a solvent such as water begins to freeze, its molecules arrange themselves in a particular pattern. </li></ul>
  49. 52. Effects of Solute Particles <ul><li>Adding a solute such as sodium chloride to this solvent changes the way the molecules arrange themselves. </li></ul><ul><li>To overcome this interference of the solute, a lower temperature is needed to freeze the solvent. </li></ul>
  50. 53. Acids <ul><li>Acids are substances that release positively charged hydrogen ions, H + , in the water. </li></ul><ul><li>When an acid mixes with water, the acid dissolves, releasing a hydrogen ion . </li></ul>Acidic and Basic Solutions
  51. 54. Acids <ul><li>The hydrogen ion then combines with a water molecule to form a hydronium ion . </li></ul><ul><li>Hydronium ions are positively charged and have the formula H 3 O + . </li></ul>
  52. 56. Properties of Acidic Solutions <ul><li>Sour taste is one of the properties of acidic solutions. </li></ul><ul><li>Another property of acidic solutions is that they can conduct electricity . </li></ul><ul><li>Acidic solutions also are corrosive , which means they break down certain substances. Many acids can corrode fabric, skin, and paper. </li></ul><ul><li>The solutions of some acids also react strongly with certain metals . </li></ul>
  53. 57. Uses of Acids <ul><li>Vinegar , which is used in salad dressing, contains acetic acid . </li></ul><ul><li>Lemons, limes, and oranges have a sour taste because they contain citric acid . </li></ul>
  54. 58. Uses of Acids <ul><li>Your body needs ascorbic acid , which is vitamin C . </li></ul><ul><li>Sulfuric acid is used in the production of fertilizers, steel, paints, and plastics. </li></ul>
  55. 59. Uses of Acids <ul><li>Acids often are used in batteries because their solutions conduct electricity . </li></ul><ul><li>Hydrochloric acid , which is known commercially as muriatic acid , is used in a process called pickling. Pickling is a process that removes impurities from the surfaces of metals. </li></ul>
  56. 60. Acid in the Environment <ul><li>Carbonic acid plays a key role in the formation of caves and of stalactites and stalagmites . </li></ul><ul><li>Carbonic acid is formed when carbon dioxide in soil is dissolved in water. </li></ul><ul><li>When this acidic solution comes in contact with calcium carbonate—or limestone rock—it can dissolve it, eventually carving out a cave in the rock. </li></ul>
  57. 61. Bases <ul><li>Bases are substances that can accept hydrogen ions . </li></ul><ul><li>When bases dissolve in water, some hydrogen atoms from the water molecules are attracted to the base . </li></ul>
  58. 62. Bases <ul><li>A hydrogen atom in the water molecule leaves behind the other hydrogen atom and oxygen atom. </li></ul><ul><li>This pair of atoms is a negatively charged ion called a hydroxide ion . </li></ul><ul><li>A hydroxide ion has the formula OH – . </li></ul><ul><li>Most bases contain a hydroxide ion , which is released when the base dissolves in water. </li></ul>
  59. 63. Properties of Basic Solutions <ul><li>Basic solutions feel slippery . </li></ul><ul><li>Bases also taste bitter . </li></ul><ul><li>Like acids, bases are corrosive . </li></ul><ul><li>Basic solutions contain ions and can conduct electricity . Basic solutions are not as reactive with metals as acidic solutions are. </li></ul>
  60. 64. Uses of Bases <ul><li>Bases give soaps, ammonia, and many other cleaning products some of their useful properties. </li></ul><ul><li>The hydroxide ions produced by bases can interact strongly with certain substances, such as dirt and grease. </li></ul>
  61. 65. Uses of Bases <ul><li>Chalk and oven cleaner are examples of familiar products that contain bases. </li></ul><ul><li>Your blood is a basic solution. </li></ul>
  62. 66. Click box to view movie.
  63. 67. What is pH? <ul><li>pH is a measure of how acidic or basic a solution is. </li></ul><ul><li>The pH scale ranges from 0 to 14 . </li></ul><ul><li>Acidic solutions have pH values below 7 . </li></ul><ul><li>A solution with a pH of 0 is very acidic. </li></ul><ul><li>A solution with a pH of 7 is neutral . </li></ul><ul><li>Basic solutions have pH values above 7. </li></ul>
  64. 68. pH Scale <ul><li>A change of 1 pH unit represents a tenfold change in the acidity of the solution. </li></ul><ul><li>For example, if one solution has a pH of 1 and a second solution has a pH of 2 , the first solution is not twice as acidic as the second—it is ten times more acidic . </li></ul>
  65. 69. Strengths of Acids and Bases <ul><li>The difference between food acids and the acids that can burn you is that they have different strengths. </li></ul><ul><li>The strength of an acid is related to how easily the acid separates into ions, or how easily a hydrogen ion is released, when the acid dissolves in water. </li></ul>
  66. 70. Strengths of Acids and Bases <ul><li>In the same concentration, a strong acid—like hydrochloric acid—forms more hydronium ions in solution than a weak acid does—like acetic acid. </li></ul>
  67. 71. Strengths of Acids and Bases <ul><li>More hydronium ions means the strong-acid solutions has a lower pH than the weak-acid solution . </li></ul>
  68. 72. Strengths of Acids and Bases <ul><li>The strength of a base is related to how easily the base separates into ions , or how easily a hydroxide ion is released , when the base dissolves in water . </li></ul>
  69. 73. Indicators <ul><li>Indicators are compounds that react with acidic and basic solutions and produce certain colors, depending on the solution’s pH. </li></ul><ul><li>Because they are different colors at different pHs, indicators can help you determine the pH of a solution. </li></ul><ul><li>When litmus paper is placed in an acidic solution , it turns red . When placed in a basic solution, litmus paper turns blue . </li></ul>
  70. 74. Neutralization <ul><li>Heartburn or stomach discomfort is caused by excess hydrochloric acid in the stomach. </li></ul><ul><li>An antacid product, often made from the base magnesium hydroxide, Mg(OH) 2 , neutralizes the excess acid. </li></ul><ul><li>Neutralization (new truh luh ZAY shun) is the reaction of an acid with a base. It is called this because the properties of both the acid and base are diminished, or neutralized . </li></ul>
  71. 75. How does neutralization occur? <ul><li>Recall that every water molecule contains two hydrogen atoms and one oxygen atom . </li></ul><ul><li>When one hydronium ion reacts with one hydroxide ion , the product is two water molecules . This reaction occurs during acid-base neutralization . </li></ul>
  72. 77. How does neutralization occur? <ul><li>Equal numbers of hydronium ions from the acidic solution and hydroxide ions from the basic solution react to produce water. </li></ul><ul><li>Pure water has a pH of 7, which means that it’s neutral. </li></ul>

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