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Acids and Bases

Acids and Bases. Chapter 6.3 & 6.4. Mini-Project. Organize the following formulas into two groups with four formulas in each group: HNO 3 , NaOH, H 2 SO 4 , H 2 CO 3 , Ca(OH) 2 , KOH, H 8 PO 4 , Mg(OH) 2. One way to organize them into groups is: Group One Group Two HNO 3 NaOH

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Acids and Bases

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  1. Acids and Bases Chapter 6.3 & 6.4

  2. Mini-Project Organize the following formulas into two groups with four formulas in each group: HNO3, NaOH, H2SO4, H2CO3, Ca(OH) 2, KOH, H8PO4, Mg(OH) 2 One way to organize them into groups is: Group One Group Two HNO3 NaOH H2SO4 Ca(OH) 2 H2CO3 KOH H8PO4 Mg(OH) 2 Group One formulas represent acids. Group Two formulas represent bases.

  3. Water HCl H+ + Cl- ACIDS • Taste sour (lemon, vinegar) • React with metal (corrosion) • React with carbonates (makes bubbles of CO2 • Turns blue litmus RED • In Water forms Hydrogen ION

  4. Water NaOH Na+ + OH- BASES • Taste Bitter (soap, tonic water) • Feel Slippery (soap) • Turns Red Litmus Blue • In water, forms HYDROXIDE (OH-) ion • React with Acids to make water

  5. Indicators • An Indicator is a chemical that turns colors under certain conditions. • Litmus paper is paper with the indicator litmus on it. • Litmus turns blue when in contact with a base • Litmus turns red when in contact with an acid • There are many different indicators • Bromthymol blue, universal, malachite green, etc.

  6. Why are Some Solutions Acid & Others Base? • Acid solutions contain more H+ ions than OH- ions. • Base solutions contain more OH- ions than H+ ions. • Water is the standard for Acid/Base and is defined as NEUTRAL • Water has equal amounts of H+ and OH- ions

  7. Arrhenius Model of Acids/Bases • Substance is an acid if it contains hydrogen and dissociation causes hydrogen ions to form in solution • Substance is a base if it contains a hydroxide and dissociates to produce hydroxide ions in solution

  8. Bronsted-Lowry Model • Acid is a hydrogen ion donor • Base is a hydrogen ion receptor • This is a broader definition than Arrhenius model because there are substances that cause donation or reception without having hydrogen in them.

  9. Electrolytes • Acids and Bases are ELECTROLYTES • They ionize in water • They conduct electricity

  10. Strong vs. Weak • Weak Acids/Bases vs. Strong Acids/Bases • Strong acids/bases ionize completely • Weak acids/bases only partly ionize • Strong Bases are just as dangerous as Strong Acids • They react with most things they touch

  11. More • Concentrated vs. Dilute • Concentrated means lots of acid/base in a little bit of water • Dilute means a little bit of acid/base in a lot of water • Concentrated Acids and Bases are VERY Dangerous • They react quickly with many substances

  12. Common Acids

  13. Common Bases

  14. Acid Rain • Acid rain comes from rain collecting gasses from the air to create acids: • Carbon Dioxide = carbonic acid • Sulfur oxides = sulfuric acid • Nitrogen oxides = nitric acid • Damages statues, buildings, kills forests, kills fish

  15. pH Scale

  16. pH • pH stands for ‘per hydrion’ • It measures the amount of hydrogen ions in solution • Water is defined as ‘neutral’ • Water has one H+ and one OH- equal numbers • The concentration of H+ in water is 1.0 x 10-7 • The pH of water is 7 • A lower pH means MORE Hydrogen ions (Acid) • 10-6 is Larger than 10-7 • A higher pH means LESS hydrogen ions (Base) • 10-8 is Smaller than 10-7 • pH scale is a way of showing this relationship of hydrogen ions

  17. pOH • In water concentration of H+ = concentration of OH- • So [H+] = [OH-] = 1.0 x 10-7 • Think about it: • H2O is the same as H-O-H which is H+ + OH- • So pOH of water is also 7 • pH + pOH always equals 14, so • pH scale goes from 1 to 14

  18. Common Items on the pH Scale

  19. Neutralization Reactions

  20. HCl + NaOH H2O + Na+ + Cl- Acid-Base Reactions • Neutralization reaction is a reaction between an acid and a base • Makes Water + Salt • Solution becomes Neutral (not acid or base) • NOTE: salt is a ‘category’ of chemicals, not always sodium chloride

  21. Acid-Base Reactions • Mg(OH)2 + 2 HCl → MgCl2 + 2H2O • Note: • Cation from base (Mg) is combined with anion from acid (Cl) • The salt is MgCl2 • The H+ and OH- always combine to form water

  22. Acid-Base Titration • Acid/Base Titration is the stoichiometry of acid/base reactions. • Titration is a method for determining the concentration of a solution by using another solution of known concentration • Uses an INDICATOR to show when the acid/base reaction is complete (neutral) • Indicator is a chemical that changes color as determined by acid or base conditions • There are many indicators with different pH points.

  23. Acid/Base Titration Curve

  24. pH Indicators

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