Acid and Base Chemistry

What comes to mind when you think acid?

Objectives

• By the end of this session, you should be able to
• Identify acids and describe some of its general characteristics

Acids

• Acids are used all the time!
• Carbonic Acid
• Ascorbic acid
• Acetic acid
• Citric Acid

Really, What is it?

• Acids are ionic substances with H⁺ as the cation
• HCl
• HBr
• HNO₃
• H₂SO₄

General Characteristics

• Most start with hydrogen (H)
• Liquids or gases
• Taste Sour (Lemons)
• Causes Severe Chemical Burns

By the end of today

• You should be able to :
• Understand what a base is and how to identify it.
• Name bases and given formula and

Bases

• Bases are ionic substances with OH^- is the anion
• NaOH --> Na⁺ + OH^-

General Characteristics

• Solids
• Taste Bitter
• Usually end in OH^-
• Very Dangerous

Acid/Base Strength

• Not based on concentration
• Based on ionization
• Strong acid/base ionizes 100%
• Weak acid/base ionizes < 100%

Steps for Naming Acids

• 1. Name it with ionic name
• Ex: HBr : Hydrogen Bromide
• 2. Use acid naming rules chart to find acid name.

Naming of Acids

Examples

• HCl
• Hydrochloric Acid
• H₂SO₄
• Sulfuric Acid

Examples

• Hydrobromic Acid
• HBr
• Carbonic Acid
• H₂CO₃

Do these in your notes

• H₃PO₄      HClO₃   �H₂CO₃      HCN    �HF HI � �    �   �  �    ��

Do these in your notes

• Nitric acid Sulfuric acid    �Acetic acid    Hydroiodic acid �Hydrobromic acid Hydrofluoric acid �� �  �  �  �

Naming Bases

• Bases follow normal ionic naming rules
• NaOH (Sodium Hydroxide)
• KOH (Potassium Hydroxide)

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Concentration, pH, and pOH

• pH is a measure of acid concentration (after ionization) in a solution
• pOH is a measure of base concentration (after ionization) in a solution

pH scale

• Numbers range from 0-14
• 7.00 is perfectly neutral
• Low numbers (0-6.99) are acidic
• High numbers (7.01-14) are alkaline/basic
• Each whole # is x10 concentration

Important formulas

• [Acid] = [H⁺]
• [Base] = [OH^-]
• pH = -log [H⁺]
• pOH = -log [OH^-]
• pH + pOH = 14

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Practice Problems

• What is the pH of a 0.00010 M solution of HCl?
• What is the [H⁺] if the pH of a solution is 2.50?
• What’s the pOH?

Practice Problem

• What’s the pOH of 0.0365 M Ba(OH)₂?
• What’s the pOH of 0.000599 M HCl

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Objectives

• By the end of today you will know what a titration is and be able to explain how to use indicators to identify when to use them.

Titration

• The operation of gradually adding one solution to another to reach an equivalence point
• Equivalence Point- Point in a titration where acid=base (pH=7)

Titration

• How do know when we reached the equivalence point?
• pH paper
• Indicator- color changing dye
• Digital sensors

Titration

• Burette - Graduated cylinder with a nozzle on the end used for titration
• Titrant – Substance in the burette
• Analyte - Substance in beaker below the burette
• Stopcock – Flow control nozzle

Titrant

Analyte

Titration Steps

1. Measure out volume of analyte and put in to Erlenmeyer flask
2. Add 2-3 drops of indicator
3. Fill the burette with titrant and record starting volume of titrant (to 0.01 mL)

Titration Steps

5. Add necessary amount of titrant to the Erlenmeyer flask until equivalence point is reached (indicator changes color)

6. Record your final volume of titrant

7. Do calculations

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Neutralization Reactions

• Double displacement reaction between acid and a base
• Acid + Base --> water and a salt
• HCl + NaOH --> H₂O + NaCl

Neutralization Reactions

• Reaction is complete when quantity of acid equals the quantity of the base (moles acid = moles base)
• Known as the “equivalence point”
• pH = 7
• M_aV_a/n_a = M_bV_b/n_b
• n is the stoichiometric coefficient

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• How many milliliters of 0.100 M HCl are required to neutralize 25.0 mL of 0.100M Ba(OH)₂? (Hint: What’s the balanced reaction?)

Calculation

• 14.75 mL of .500 M H₂SO₄ is used to reach the equivalence point. If 10.0 mL of NaOH are used, whats is the molarity of NaOH?
• 1.48 M NaOH