Presentation on theme: "Acids, Bases and Salts Acid-Base Theories CHAPTER 15 PA 530-538."— Presentation transcript:
Acids, Bases and Salts Acid-Base Theories CHAPTER 15 PA
What is an Acid? The term acid comes from the Latin term acere, which means "sour". ex. Lemon juice, vinegar, and many other foods taste sour.
AcidsBases Taste sour Corrosive React with some metals to produce H 2 Change Litmus to red acid= red React with bases to form water and salt. Bases taste bitter Feel slippery Corrosive Change Litmus to blue base = Blue Become less basic when mixed with acids.
Always Use Ref. Tables (vinegar)
Table L Common Bases Formula Name NaOH(aq) sodium hydroxide KOH(aq) potassium hydroxide Ca(OH) 2 (aq) calcium hydroxide NH 3 (aq) aqueous ammonia
Svante Arrhenius Swedish chemist, proposed theories of electrolytic disassociation (acids/bases) and greenhouse effect.
Arrhenius Theory of Acids & Bases Acid - produces hydrogen ion (H + ) in a solution. HA H + + A¯ Base – produces hydroxide ion (OH¯) in a solution. XOH X + + OH¯
Nature of the Hydrogen Ion or Proton Proton is so small that does not exist isolated in water. H + + H 2 O H 3 O + Hydronium Ion
Nature of Hydroxide Ion The presence of OH - makes the substance an electrolyte and a base. Alcohols contain the OH group but are NOT IONIC COMPOUNDS therefore alcohols are NOT bases. C H O are molecular compounds NOT ionic compounds!!!!
HOW TO NAME ACIDS NO OXYGEN IN FORMULA HYDRO ACID HCl Hydrochloric acid HBr Hydrobromic acid HF Hydrofluoric acid H 2 S Hydrosulfuric acid OXOA CIDS CONTAIN OXIGEN IN FORMULA ENDING OUS if ion ends ITE IC if ion ends in ATE Use table E
Solutions of Ionic Compounds conduct electricity = Electrolytes Electrolytes – ions (charged particles) in solution. HCl (aq) H + + Cl - Hydrochloric Acid H+H+ Cl -
Solutions ; Release OH - (aq) Metal (+) and Non-Metal (-) Electrolytes – conduct electricity when dissolved in H 2 O
Solutions = Salts (ionic), acids, & bases Salts = ionic (+) (-) Strong Acid & Base Weak Acid or Weak Base Covalent = no ions brightdim dark
Conductivity apparatus Electrolytes – conduct electricity when dissolved in water
STRONG ACIDS COMPLETELY DISSOCIATED If the solution is 2 M, 2 mol of H + and 2 mol of Cl-
WEAK ACIDS Partially dissociated. Molecules stay together and only some of them dissociate.
Binary Acids - composed of hydrogen + 1 other element Ex. HCl Hydrochloric Acid Binary Acids begin with “hydro -” followed by name of other element; modified with an ending of “-ic”
Ternary Acids - molecular (covalent) - composed of hydrogen + oxygen containing polyatomic ion (Ref. E) Ex. HNO 3 Nitric Acid (NO 3 1- Nitrate ion) HNO 2 Nitrous Acid (NO 2 1- Nitrite ion) H 2 SO 4 Sulfuric Acid(SO 4 2- Sulfate ion) Ternary Acids = Anion suffix (-ate or -ite) is dropped and replaced with “-ic” or “-ous” respectively.
TABLE M common acids HCl(aq) hydrochloric acid HNO 3 (aq) nitric acid H 2 SO 4 (aq) sulfuric acid H 3 PO 4 (aq) phosphoric acid H 2 CO 3 (aq) carbonic acid CH 3 COOH(aq) ethanoic acid HC 2 H 3 O 2 (aq) (acetic acid)
Common Acids – Ref. K Nitric acid (HNO 3 ) 1) Most is used to make fertilizer 2) Well known for making explosives Hydrochloric acid (HCl) 1) Most is used to clean metals (pickling) 2) Also called muriatic acid Sulfuric acid (H 2 SO 4 ) 1) The most widely used chemical in the world 2) Most of it is used to make fertilizer 3) It is a good dehydrating agent 4) It is used in car batteries
Properties of Bases 1)Bases feel slippery 2)Bases are electrolytes 3)Bases are corrosive, poisonous, and can cause severe burns (Lye = conc. NaOH) 4)Bases turn litmus blue; Blue = Base 5)Bases = pH greater than 7 Big in Base 6) Bases neutralize acids
Common Bases – Ref. L Ammonia NH 3 1) The most widely used base 2) Used in household cleaning materials 3) Used as fertilizer; adds nitrogen to soil Calcium hydroxide (caustic lime) Ca(OH) 2 1) Used to make mortar and plaster 2) Used to help neutralize acid soil Sodium hydroxide (Lye) NaOH 1) One of the strongest bases 2) Used in oven cleaners and drain cleaners
Always Use Ref. Tables Acids ending = “- ic” Bases = Metal + hydroxide (vinegar)
Reactions of Acid with metals Use table J! Metals above H 2 in table J react with acids by a single replacement reaction producing H 2. 2 HCl + Zn H 2 + ZnCl 2
Neutralization Reaction Acids and bases react to neutralize each other, forming water and a salt: Acid + Base Water + Salt HA + XOH H 2 O + XA Double Replacement Reaction
Titration Is a process that uses a neutralization to determine the concentration of an acid or a base. Concentration in molarity is the amount of moles of solute per liter of solution. When the reaction of neutralization is 1:1 we use the following formula in a titration Ma x Va = Mb x V b
Vocabulary Standard solution : the solution of known molarity Buret : instrument to measure exact volumes of liquids Erlenmeyer Flask Indicator : a substance that changes color in the presence of an acid or base. End point: when the amount of H + = OH -
At the end point Ma x Va = Mb x V b
Base OH - Acid H + Acid – Base Titration Erlenmeyer flask Two Burets with valves at bottom. Record vol. in mL (twice) Color indicator = phenolphthalein
What is pH ? pH is the negative logarithm of the hydrogen ion concentration = pH = - log [H + ] Remember that sometimes H + is written H 3 O +, so pH = - log [H 3 O + ] means the same thing.
pH Scale = log (base 10) scale An increase of 1 in pH corresponds to a decrease of a factor of 10 in H + concentration. pH is.. Big in Base & Blue
Typical pH Values of Common Materials Oven Cleaner / Drain Cleaner Hair Remover Baking Soda Soap Ammonia (NH 3 ) Lemon Juice Coffee / Tea Blood Battery Acid Saliva Pure Water Seawater Stomach Acid Milk Vinegar, Soft Drinks Tomatoes Basic Acidic Neutral
More about pH Kw = dissociation constant for water = x = [H + ] x [OH - ] = [ ] x [ ] A neutral solution has a pH of 7. [H+] = [OH-] = 1 x M
P 185 answers 40)4 41)2 42)2 43)1 44)4 45)2 46)25 ml 47)3000ml 48)20mL 49)50mL 50)6M
P 178 rb answers 14. chlorate 15 a) hydrosulfuric acid b) hydrobromic acid c) lithium hydroxide d) magnesium hydroxide 16. An electrolyte can also be a base or a salt. An indicator can be added to test if is an acid or a base.
Page 187 answers 61)4 62)1 63)3 64)3 65)3 66)2 67)1 68)1 69)4 70)2 71)Bromocresol green 72)Bet 5.4 and 6 73)A blue yellow 74) B 75) 1
Handout Answers 1)2 2)2 3)4 4)2 5)3 6)3 7)4 pH=6 Methyl orange/ Bromthymol blue Bromocresol green