Acids, Bases, Salts and pH

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Acids, Bases, Salts and pH

• Joe Walker Middle School
• Physical Science
• Hayhurst/Sour

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Acids

• Acids are chemicals in which the positive ion is
  a hydrogen atom.
• for example HCl or H2SO4
• When mixed with water they produce a free
  hydrogen ion that combines with a water molecule
  to produce a hydronium ion (H3O)
• H1 H2O ? H3O1
• An acid is a substance that releases hydrogen
  ions when it breaks apart in water.

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Physical Properties of Acids

• 1. Taste sour
• 2. React with metals to produce hydrogen
• 2HCl 2Na ? 2NaCl H2
• 3. Conduct electricity.

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Bases

• Bases are substances in which the negative ion is
  an ion called hydroxide (OH)-1.
• For example NaOH, or KOH
• used to make soap, household cleaners,
  fertilizers, and explosives.

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Physical Properties of Bases

• 1. Taste bitter
• 2. Feel slippery
• 3. Conduct electricity
• 4. Sometimes Caustic. That is they eat away at
  certain substances and they are irritating or
  damaging to skin.

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Salts

• A salt is a compound formed from the positive
  metal ions of a base and a negative nonmetal ion
  of an acid.
• For example NaCl, K2SO4
• Are the product of a reaction between an acid and
  a base, along with water.

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Physical Properties of Salts

• They form crystals when in solid form
• They usually have a higher hardness because of
  their ionic bonding.
• An acid plus a base yields a salt and water.
• HCl NaOH ? NaCl HOH
• or
• HCl NaOH ? NaCl H2O

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Neutralization

• A reaction between an acid and base.
• The products of a neutralization reaction are a
  salt and water.

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The pH Scale

• The pH scale gives a measure of the concentration
  of positive hydrogen ions in a solution.
• a way of describing the acidic or basic strength
  of a solution.
• the acidity of a solution can be expressed by
  using the pH scale

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The pH Scale

• the scale ranges from 0 to 14
• acids range from 0 to 7, with 0 being the
  strongest acid
• bases range from 7 to 14, with 14 being the
  strongest base.
• pure water, which is neither acid nor base, has a
  pH level of 7 or is neutral

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Indicators

• Indicators are substances that visibly show a
  change in the nature of a chemical system.
• Universal indicator- an acid/base indicator that
  shows, by color, the pH of a substance.

ACIDIC
NEUTRAL
BASIC