Acids and Bases Part 1

Acids and Bases Part 1:

Acidity, Basicity, and Concentrations

By Abby Fancsali

What are Acids?

• Acids are a distinct set of compounds that share common properties as aqueous solutions​

  • Acids tend to have a sour taste and most are poisonous

  • Acids change the colors of acid-base indicators

  • Acids react with bases to produce salts and water

    • Salt is any ionic compound, not just NaCl

  • Acids conduct electric current

  • Some acids react with metals and release Hydrogen gas (H₂)

  • Produce Hydronium ions (H₃O⁺)

Types of Acids

• ​Binary Acids: contain only two different element, Hydrogen and an electronegative element

  • Naming Ru​les

    • The Name begins with the prefix hydro

    • the root of the name follows the name of the second element, with the ending changed to -ic

      • Example: HCl

        • Hydro from hydrogen

        • Chlorine changes to Chloric

        • Hydrochloric Acid

Multiple Choice

Which formula shows hydrofluoric acid

• HF

• HI

• H₂S

• HBr

Types of Acids

• ​Oxyacid: an acid that is a compound of hydrogen, oxygen, and third element

  • the third element is usually a non metal

  • Most are bases on anions, and take their names from that

    ​

Common Industrial Acids

• ​Sulfuric Acid

  • most commonly produced industrial chemical in the world

  • Used to refine Petroleum and Metals, as well as fertilizer production

• ​Nitric Acid

  • Pure nitric acid needs to be dissolved in water for stability

  • Used to make explosives, rubber, plastics, dyes, and medicines

• Phosphoric Acid

  • Is sometimes used as a flavoring agent

• Hydrochloric Acid

  • ​Produced in the stomach for digestion

• Acetic acid (Found in Vinegar​)

What are Bases

• Bases are also compounds that share unique properties

  • Aqueous Bases taste Bitter, many are caustic

  • Bases change the color of acid-base indicators​

  • Dilute aqueous solutions of bases feel slippery

  • Bases react with acids to produce salts and water

  • Bases Conduct Electric Currents

  • Bases react with oils

    • Many Bases are used in cleaning agents

  • Produce Hydroxide ions (OH^-)

Arrhenius Acids and bases

• Svante Arrhenius (1859-1927): Swedish chemist who theorized that acids and bases conduct electricity, they must produce ions in solutions

  • Arrhenius Acid: A compound that increases the concentration of Hydrogen ions, H⁺, in water

  • Arrhenius Base: a substance that increases the concentration of Hydroxide ions, OH^-, in water

Strength of Acids and Bases

• Strong Acids: ionize completely in aqueous solutions and add many hydronium ions

  • Strong Acids are strong electrolytes

• Weak Acids: release few ions in aqueous solutions

• Strong Bases: add many Hydroxide ions to a solution and are strong electrolytes

• Weak Bases add few Hydroxide ions to a solution​

Calculating the ionization of acids and bases

• When Hydronium ions and Hydroxide ions are equal in concentration in a solution, we say the solution is in equilibrium

• The point of equilibrium can be shown using a constant, K_w

  • This point of equilibrium is equal to the concentration of Hydronium ions multiplied by the concentration of Hydroxide ions

    • K_w=[H₃O]*[OH]​ =1.0 x 10^-14

      • If given a concentration of an acid or a base, you can calculate the number of ions using this equation

Determining [OH^-] or [H₃O⁺] Sample Problem

• What is [OH^-] in a 3.00 x 10^-5 M solution of HCl

  • HCl is a strong acid, so it's concentration tells us the concentration of [H₃O⁺]

    • ​[H₃O⁺]=3.00 x 10^-5

    • We can plug this into our equation and solve for [OH^-]:

      • 1.0 x 10^-14 = 3.00 x 10^-5 * [ OH^-]

Determining [OH^-] or [H₃O⁺] Sample Problem

• Calculate the hydronium ion concentration in an aqueous solution that has a hydroxide ion concentration of 7.24 x 10^-4 M

  • Plug our hydroxide concentration into the equation and solve

    • ​[H₃O] * 7.24 x 10^-4 ​ =1.0 x 10^-14