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CHAPTER 5: Compounds are classified in different ways

CHAPTER 5: Compounds are classified in different ways. Acid and Bases. BOTH concentrated bases and acids are dangerous Bee stings are acidic with a pH of 3.5

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CHAPTER 5: Compounds are classified in different ways

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  1. CHAPTER 5: Compounds are classified in different ways

  2. Acid and Bases • BOTH concentrated bases and acids are dangerous • Bee stings are acidic with a pH of 3.5 • Not only is the venom acidic from a hornet and wasp, it also contains a pheromone that alarms other wasps in the area to come and ATTACK. • Scorpions squirt acid from its mouth onto its victims to dissolve the tissue before sucking up its slushy remains • Only 20 species of scorpions that can kill or hurt a human with a sting • Takes up to 12 hours to die after a sting

  3. ACIDS AND BASES • In concentrated forms, acids and bases are corrosive • A pH scale is a scale that measure how acidic and how basic a solution is • Acids have a pH less than 7 • Bases have a pH greater than 7. An alkaline solution is another term describing a basic solution • A pH of 7 means that the solution is neutral, neither acidic or basic

  4. ACIDS • Many compounds take on acidic properties only when dissolved in water • Therefore, the formula will contain the subscript (aq) which means aqueous (dissolved in water) • Have “Hydrogen- H” on the left side of the formula and (aq) • Example • HCl(g) • HCl (aq) • When dissolved in solution, acids produce hydrogen ions which are highly acidic • So ACTUALLY • HCl(aq)  H+ ions + Cl- ions + H2O • HCl(aq) H+ (aq) + Cl- (aq) -Hydrogen Chloride – NOT AN ACID - Hydrochloric ACID Cl- H+ H+ Cl-

  5. NAMING ACIDS • When naming acids, first make sure it is in aqueous solution • Rules: • Names that are usually hydrogen _________ “ide” • Names that are usually hydrogen __________ “ate” • Names that are usuallyhydrogen __________ “ite • Hydro _________ “ic” acid • ________ “ic” acid • ___________ “ous” acid CHLOR CHLOR CARBON CARBON SULFUR SULF

  6. YOU TRY Hydrogen fluoride HF(aq) Hydrofluoric acid HClO3(aq) Hydrogen chlorate Chloric acid Hydrogen chlorite Chlorous acid HClO2(aq) HNO3(aq) Hydrogen Nitrate Nitric acid Hydrogen Bromide HBr(aq) Hydrobromic acid

  7. BASES • Bases often behave like bases when dissolved in water • Therefore, must ALSO have the subscript (aq) for aqueous • Usually written with an OH on the right side of the formula • Is Na(OH)(s) a base???? • Is Na(OH)(aq) a base??? • When bases are dissolved in water, it produces hydroxide ions (OH-) which are highly basic • So ACTUALLY • NaOH(aq)  Na+ ions + OH- ions + H2O OH- Na+ Na+ OH-

  8. NEUTRAL SOLUTIONS : pH = 7 • When you combine solutions containing H+ and OH- , you get...... • When acid solutions are mixed with basic solutions, the solutions can neutralize each other • The acidic properties and the basic properties balance each other out creating a neutral solution! H+ OH- HOH

  9. pH SCALE • The pH scale measures how acidic or basic a solution is by determining the hydrogen ion concentration • hydrogen ion concentration = pH value • Each pH value differs by 10 TIMES the hydrogen ion concentration • Example: • Stomach acid: pH = 1 • Lemon Juice: pH = 2 Stomach acid has 10 times more hydrogen ions than lemon juice

  10. pH indicators • pH indicators are chemicals that change colour according to the pH level of the solution being tested • Indicators include: Bromothymol Blue 6.0-7.6 Yellow to blue Litmus Paper 7 Red to blue Phenolphtalein 8.2-10.0 Colorless to pink

  11. DIFFERING CHARACTERISTICS Taste sour ie: lemons & vinegars Taste bitter Feels slippery Will also burn skin Burns skin on contact Ie: battery acid Red litmus blue Phenolphthalein turns pink in strong – moderate bases Blue litmus red Phenolphthalein- colorless Acids corrode metals Generally, no reaction Conductive Conductive pH less than 7 pH greater than 7 Hydrogen ions produced in aqueous solution Hydroxide ions produced in aqueous solution

  12. Salts and snails

  13. SALTS • When acids and bases react, they form salts • Salts are a class of ionic compounds that produced from neutralization reactions • It is made up of a positive ion from a base, and the negative ion from the acid • Examples: • HCl(aq) + NaOH(aq) NaCl(s) + H2O • 3H2 SO4 + 2Al(OH)(aq)  Al2(SO4)3 + H2O • 2CH3COOH + Mg(OH)2  Mg(CH3COO)2 + 2H2O

  14. Why is neutralization important? • When are stomach makes too much hydrochloric acid you get heartburn or ulcers. The acid starts to burn away at your stomach lining.... • We take a base, called antacids such as magnesium hydroxide or aluminum hydroxide to neutralize the acid making a salt and water. • Example: 3HCl + Al (OH)3 AlCl3 + 3H(OH) • We don’t take sodium hydroxide because that’s what we use unclog drains... Not our stomachs

  15. METAL OXIDES • A metal reacts with oxygen to form metal oxides • An oxide is a compound that contains at least one oxygen atom or ion, with other elements • A metal oxide is a chemical compound that contains a metal and at least one oxygen atom • Examples: • Na(s) + O2 Na2O • Mg(s) + O2  MgO • Ca(s) + O2  CaO

  16. METAL OXIDES IN WATER • When metal oxides are dissolved in water, the solution becomes basic. • For example: • Na2O(s) + H2O(l) 2NaOH(aq) • CaO(s) + H2O(l)  Ca(OH)2(aq) • Heavy metal bands have BASE players!!!

  17. NON-METAL OXIDES • A non-metal reacts with oxygen to create a non-metal oxide which are covalently bonded • They are formed when we burn fossil fuels • Examples of non-metal oxides • Carbon monoxide (CO), • Carbon dioxide (CO2) • Sulfur dioxide (SO2 ) • Non-metal oxides react with water to form acids • Example: SO2(g) + H2O(l)  H2SO3(aq) • When these oxides from burning fossil fuels are combined with water in the atmosphere, acid rain is created

  18. ACIDS AND METALS • When acids react with metals, one of the products are generally hydrogen gas. • Example: HCl(aq) + Zn(s) ZnCl2(s) + H2(g) ACIDS AND CARBONATES (CO32- ) • When acids react with carbonates, the carbonates help to neutralize the acid. This reaction tends to release carbon dioxide and water. • Example: H2 SO4 + CaCO3 CaSO4 + CO2 + H2O

  19. ORGANIC CHEMISTRY

  20. ORGANIC CHEMISTRY • - is the study of compounds containing CARBON • Organic compounds are compounds containing CARBON and usually hydrogen • Carbon has 4 electrons in its valence shell • Tends to form four covalent bonds • Having only 4 electrons allows for many different bonding possibilities! • it can bond with itself to create double or triple bonds and bond with other atoms as well • All known life forms are associated with and/or depend on reactions involving carbon

  21. HYDROCARBONS • A hydrocarbon is an organic compound that contains only carbon and hydrogen • Formed by linking chains of carbons • All hydrocarbons are flammable • Some hydrocarbons are used as fuels • Depending on the number of links, hydrocarbons tend to be liquid in room temperature

  22. ALCOHOLS - OL • Alcohols are organic compounds with carbon, hydrogen and oxygen • Simplest alcohols are • methanol CH3 OH • Ethanol CH5OH • Isopropyl alcohol CH7OH

  23. INORGANIC VS ORGANIC • Inorganic compounds generally do not contain carbon except for: • Ionic compounds containing carbonates (CO3)2- • Carbides (Al4C3 ) • Oxides (CO2, CO) • Organic compounds MUST contain carbon • Always have “C” before “H”s in formula

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