One of the chemicals used to make soaps is sodium hydroxide. Sodium hydroxide reacts with animal or vegetable fats to make glycerol and soap.

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• One of the chemicals used to make soaps is sodium
  hydroxide. Sodium hydroxide reacts with animal or
  vegetable fats to make glycerol and soap.
• Sodium hydroxide belongs to a class of compounds
  known as bases.

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Identifying Acids

• What are some general properties of acids?
• An acid is a compound that produces hydronium
  ions (H3O) when dissolved in water.

Some general properties of acids include sour
taste, reactivity with metals, and ability to
produce color changes in indicators.
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Identifying Acids

• When hydrogen chloride gas dissolves in water, it
  ionizes and forms hydronium ions and chloride
  ions.
• HCl H2O ? H3O Cl
• The solution that results is called hydrochloric
  acid.

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Identifying Acids
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Identifying Acids

• Sour Taste
• Foods that taste sour often contain acids.
• Lemons, grapefruits, limes, and oranges contain
  citric acid.
• Vinegar contains acetic acid.
• Dairy products that have spoiled contain butyric
  acid.

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Identifying Acids

• Reactivity With Metals
• The reaction between an acid and a metal is an
  example of a single-replacement reaction.
• When zinc is added to a test tube containing
  hydrochloric acid, bubbles form in the tube.
• Zn 2HCl ? H2 ZnCl2

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Identifying Acids

• Color Changes in Indicators
• An indicator is any substance that changes color
  in the presence of an acid or base.
• Litmus paper is made by coating strips of paper
  with litmus, a kind of dye derived from lichens.
• Blue litmus paper turns red in the presence of an
  acid.

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Identifying Acids

• Apples contain several acids, including malic
  acid, ascorbic acid (vitamin C), and citric acid.
• Blue litmus paper is an indicator for acids.

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Identifying Bases

• What are some general properties of bases?
• A base is a compound that produces hydroxide ions
  (OH) when dissolved in water.

Some general properties of bases include bitter
taste, slippery feel, and ability to produce
color changes in indicators.
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Identifying Bases

• Sodium hydroxide, NaOH, is an example of a base.
• When sodium hydroxide dissolves in water, it
  dissociates into sodium ions and hydroxide ions.
• NaOH ? Na OH

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Identifying Bases

• The plaster in this boys cast contains a base.

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Identifying Bases

• Bitter Taste
• Without sugar, chocolate tastes bitter. Cacao
  beans contain a base that gives unsweetened
  chocolate its bitter taste.
• Many liquid medicines contain bases. Fruit
  flavorings are often added to mask the taste of
  these basic solutions.

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Identifying Bases

• Slippery Feel
• Bases feel slippery. Wet soap and many cleaning
  products that contain bases are slippery to the
  touch.
• When wet, some rocks feel slippery because the
  water dissolves compounds trapped in the rocks,
  producing a basic solution.

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Identifying Bases

• Color Changes in Indicators
• Bases turn red litmus paper blue.
• Phenolphthalein is another acid-base indicator.
• In a solution containing a base, phenolphthalein
  is red.
• In a solution containing an acid, phenolphthalein
  is colorless.

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Identifying Bases

• These hydrangea flowers contain natural
  indicators. The color of the flowers depends on
  whether the plant is growing in acidic or basic
  soil.
• When hydrangeas grow in acidic soil, the flowers
  are bluish-purple. When hydrangeas grow in basic
  soil, the flowers are pink.

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Neutralization and Salts

• What are the products of neutralization?
• The reaction between an acid and a base is called
  neutralization.

The neutralization reaction between an acid and a
base produces a salt and water.
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Neutralization and Salts

• The negative ions in an acid combine with the
  positive ions in a base to produce an ionic
  compound called a salt.
• The hydronium ions from the acid combine with the
  hydroxide ions from the base to produce water.

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Neutralization and Salts

• When hydrochloric acid reacts with sodium
  hydroxide, a neutralization reaction occurs.
• If you let the water in the resulting solution
  evaporate, sodium chloride would crystallize out
  of solution.

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Neutralization and Salts

• Table salt is the most common example of a salt
  compound.
• Baking soda, NaHCO3, is produced during the
  neutralization reaction between sodium hydroxide
  and carbonic acid, H2CO3.
• The ocean contains many dissolved salts,
  including chlorides and sulfates of potassium,
  calcium, magnesium, and sodium.

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Neutralization and Salts

• The common salts listed in the table can all be
  made by reacting an acid with a base.

21
Proton Donors and Acceptors

• What are proton donors and proton acceptors?

Acids can be defined as proton donors, and bases
can be defined as proton acceptors.
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Proton Donors and Acceptors

• When an acid and a base react in water, a proton
  from the hydronium ion from the acid combines
  with the hydroxide ion (OH) from the base to
  form water (H2O).
• Acids lose, or donate, protons. Bases accept
  protons, forming water, a neutral molecule. This
  definition allows you to classify a wider range
  of substances as acids or bases.

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Proton Donors and Acceptors

• Based on the definitions of acids and bases that
  you read earlier in this section, water is
  neither an acid nor a base.
• Using the proton-donor or proton-acceptor
  definition, water can act as either an acid or a
  base.

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Proton Donors and Acceptors

• When hydrogen chloride dissolves, water acts as a
  base. It accepts a proton from hydrogen chloride
  and becomes a hydronium ion.

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Proton Donors and Acceptors

• When hydrogen chloride dissolves, water acts as a
  base. It accepts a proton from hydrogen chloride
  and becomes a hydronium ion.

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Proton Donors and Acceptors

• When hydrogen chloride dissolves, water acts as a
  base. It accepts a proton from hydrogen chloride
  and becomes a hydronium ion.

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Proton Donors and Acceptors

• When ammonia dissolves, water acts as an acid. It
  donates a proton to the ammonia, which acts as a
  base.

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Proton Donors and Acceptors

• When ammonia dissolves, water acts as an acid. It
  donates a proton to the ammonia, which acts as a
  base.

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Proton Donors and Acceptors

• When ammonia dissolves, water acts as an acid. It
  donates a proton to the ammonia, which acts as a
  base.

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Assessment Questions

• What ion is formed when a base dissolves in
  water?
• hydroxide ion
• hydronium ion
• hydrogen ion
• sodium ion

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Assessment Questions

• What ion is formed when a base dissolves in
  water?
• hydroxide ion
• hydronium ion
• hydrogen ion
• sodium ionANS A

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Assessment Questions

• What products are formed in a neutralization
  reaction?
• an acid and a base
• water and a proton
• a base and a salt
• water and a salt

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Assessment Questions

• What products are formed in a neutralization
  reaction?
• an acid and a base
• water and a proton
• a base and a salt
• water and a saltANS D

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Assessment Questions

• In the reaction between ammonia and water to form
  an ammonium ion, water acts as a(n)
• acid because it donates an electron to ammonia.
• base because it donates an electron to ammonia.
• acid because it donates a proton to ammonia.
• base because it donates a proton to ammonia.

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Assessment Questions

• In the reaction between ammonia and water to form
  an ammonium ion, water acts as a(n)
• acid because it donates an electron to ammonia.
• base because it donates an electron to ammonia.
• acid because it donates a proton to ammonia.
• base because it donates a proton to
  ammonia.ANS C

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Assessment Questions

• A food that contains acidic compounds can often
  be identified by its bitter taste.TrueFalse

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Assessment Questions

• A food that contains acidic compounds can often
  be identified by its bitter taste.TrueFalse
• ANS F, sour