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Chemistry
Periodic table
Chemical reaction
Matter
Atoms
Chemical bonding
Electrolytes
Hydrocarbons
Organic chemistry
PreQuiz (1)
1. Define “ionization”:a) substance conducts electricity; b) substance requires positive/negative charge; c) Net charge of ions is 0
2. Ca2+ is required for
a) enzymes; b) DNA/RNA; c) bones and teeth3. An example of an electrolyte is a(n)
a) acid; b) base; c) salt4. Define “acid”:
a) substance that yields H+ ions in water; b) substance that yields OH- ions in water; c) substance that yields salt in water
5. Weak acidsa) conduct no electricity when ionized in water; b) completely ionize in water; c) partially ionize in water
6. Which of the following compounds is used to treat excess of stomach acida) CaCO3; b) NaCl; c) HCl
7. An example of a base isa) vinegar; b) soda; c) sodium chloride
8. Bases are less dangerous than acids in term of skin contacta) true; b) false; c) who cares
9. The reaction between an acid and base is calleda) equilibrium; b) hydrolysis; c) neutralization
Learning activities (1)
• Electrolytes– Define common terms
• Acids, bases, neutralization– Understand theory of ionization– Identify ions important to human body– Explain properties of acids and bases– Write a neutralization reaction– Discuss the use of acids and bases in body
Definitions
• Definition: Ionization– Substance acquires negative/positive charge by gaining/losing electrons
(UNIT 4: Ion formation)– In water: substance breaks up into ions Na+ and Cl-
• Definition: Electrolyte– Substance that undergoes ionization – In water: solution of electrolyte conducts energy– Examples: Salts, acids, bases
Sackheim’s Chemistry: Chapter 11
Salt (NaCl) in water (H2O)
“Ionization of an electrolyte”
Ionization
• Equilibrium– Between ionic compound (NaCl) and free ions (Na+ + Cl-)
• Dissociation– Separation of ions (separation of Na+ and Cl-)
Sackheim’s Chemistry: Chapter 11
Ionic compound, crystal latticDoes not conduct electricity
Free ions in water solutionDoes conduct electricity
Theory of ionization
• Svante Arrhenius (1887)
Behavior of electrolytes in solution:1. Electrolytes in water: break up into ions
(ionization)2. Ions can have a positive or negative charge3. Negative + positive charges = zero
(molecules are neutral)4. Solutions of electrolytes conduct electricity
(because of ions)5. Nonelectrolytes do not conduct electricity
(because no ions)
Sackheim’s Chemistry: Chapter 11
Strong vs. Weak electrolytes
• Some electrolytes conduct more electricity than other…?
• Strong electrolytes– Dissociates (breaks up) completely into ions (no equilibrium)
• Weak electrolytes– Disocciates only partially (equilibrium)
Sackheim’s Chemistry: Chapter 11
Important ions
Ion Symbol Function
Calcium Ca2+ Necessary for clotting blood, digestion, formation of bones and teeth, action of muscle (heart)
Iron Fe2+ Necessary for formation of hemoglobin and cytochromes
Sodium Na+ Extracellular postive ion
Potassium K+ Intracellular positive ion
Chloride Cl- Negative ion
Bicarbonate HCO3- Extracellular negative ion and blood buffer
Iodide I- Present in hormones
Ammonium NH4+ Maintaining acid-base balance
Phosphate PO43- Necessary for formation of bones and teeth
Magnesium Mg2+ Activator for many enzyme systems
Sackheim’s Chemistry: Chapter 11
Acids (1)
• Substance that yield hydrogen ions (H+) in water• Common in daily live
– Fruits– Vinegar– Soft drinks– Body
Citric acid
Acetic acid
Phosphoric acid
Hydrochloric acid
Sackheim’s Chemistry: Chapter 12
Sour taste!
Acids (2)
• Acids donate/yield hydrogen ions (H+) in water
– Strong acids: completely ionized in water
– Weak acids: partially ionized in water
– Diprotic acid: Donate two protons per molecule
hydrogen ion: proton
equilibrium
Monoprotic acids
Sackheim’s Chemistry: Chapter 12
Antacids
• Stomach secrets acid (digestion of proteins)– Hyperacidity: high HCl concentration– Hypoacidity: low HCl concentration
• Hypoacidity– Dilute HCl to overcome deficiency
• Hyperacidity– Antacids: react with excess stomach acid– TUMS®: CaCO3
acid antacid salt gas water
Sackheim’s Chemistry: Chapter 12
also used to treat peptic ulcer by decreasing stomach acids
Dangerous
• Strong acids – Aggresive chemicals (corrosive)– Attack clothing
– Damage tissues (skin burn)
Sackheim’s Chemistry: Chapter 12
Wash with water Treat with NaHCO3
(to neutralize)
Medical use of acids
• Medical importance– Hydrochloric acid (HCl)
• Treat hypoacidity
– Nitric acid (HNO3)• Test presence of albumin (protein) in urine
– Di/tri-chloroacetic acid (C2H2Cl2O2/C HCl O )₂ ₃ ₂• Remove warts
– Hypochlorous acid (HClO)• Disinfect floors and walls hospital
– Boric acid (H3BO3)• Has been used as germicide (to kill microbes)
– Acetylsalicyclic acid (aspirin)• Analgesic (painkiller) and antipyric (against fever)
– Ascorbic acid (vitamin C)• Prevents vitamin C deficiency (scurvy)
Bases (1)
• Substance that yield hydroxide ions (OH-) in water• Common in daily live
– Soap– Houshold ammonia– Baking soda– Bleach
Sodium hydoxide
Sodium bicarbonate
Ammoniumhydroxide
Sodium hypochloride
Sackheim’s Chemistry: Chapter 12
Bitter taste, slippery feeling
Bases (2)
• Bases yield hydroxide ions (OH-) in water
• More general: bases accept hydrogen ions (H+) in water
yields hydroxide ion
equilibrium
accepts proton
accepts proton
Strong base
Weak base
Dangerous
• Strong bases– Damages tissues (react with proteins/fats)– Serious skin burn
– So: do not wash diapers with strong soap
Sackheim’s Chemistry: Chapter 12
Wash with water
Medical use of bases
• Medical importance– Sodium hydroxide (NaOH)
• Soap
– Calcium hydroxide (Ca(OH)2)• Overcome excess stomach acidity (antacid)• Antidote to oxalic acid poisening
– Magnesium hydroxide (Mg(OH)2)• Antacid for stomach• Laxative
– Spirits of ammonia (NH4OH and (NH4)2CO3)• Heart and respiratory stimulant
Sackheim’s Chemistry: Chapter 12
Neutralization reactions
• Acid reacts with base (alkali) to form water and salt:
• Net equation (simplified view):
• Example: “Antacids that neutralize stomach acid”
“NEUTRALIZATION”Acid neutralizes BaseBase neutralizes Acid
Proton (acid)
Hydroxide (alkali)
Water
Sackheim’s Chemistry: Chapter 12
Acid and base
EXPERIMENT 003Title: Vinegar VulcanoTopic: Acid/base reactions
1. Place a tablespoon of the baking soda into glass
2. Add a few drops of water3. Pour in a dash of the vinegar and
watch the reaction taking place
4. Repeat the experiment, while adding a few drops of soap detergent to the soda/water mixture
What’s happening?
• What is the reason of the foam formation?
– Neutralization reaction: acid + base water + salt (+ gas)– CO2 that is formed creates the foam (as in a glass of coke)– Soap detergent: traps bubbles stable foam
PostQuiz (1)
1. Define “ionization”:a) substance conducts electricity; b) substance requires positive/negative charge; c) Net charge of ions is 0
2. Ca2+ is required for
a) enzymes; b) DNA/RNA; c) bones and teeth3. An example of an electrolyte is a(n)
a) acid; b) base; c) salt4. Define “acid”:
a) substance that yields H+ ions in water; b) substance that yields OH- ions in water; c) substance that yields salt in water
5. Weak acidsa) conduct no electricity when ionized in water; b) completely ionize in water; c) partially ionize in water
6. Which of the following compounds is used to treat excess of stomach acida) CaCO3; b) NaCl; c) HCl
7. An example of a base isa) vinegar; b) soda; c) sodium chloride
8. Bases are less dangerous than acids in term of skin contacta) true; b) false; c) who cares
9. The reaction between an acid and base is calleda) equilibrium; b) oxidation; c) neutralization