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Acids & Bases

Acids & Bases. Acids react with bases Acids are electrolytes Acids act on some metals to produce H 2(g) Acids turn litmus paper RE D Acids taste SOUR. Bases react with acids Bases are electrolytes Bases feel slippery Bases turn litmus paper B LUE Bases taste BITTER.

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Acids & Bases

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  1. Acids & Bases

  2. Acids react with bases Acids are electrolytes Acids act on some metals to produce H2(g) Acids turn litmus paper RED Acids taste SOUR. Bases react with acids Bases are electrolytes Bases feel slippery Bases turn litmus paper BLUE Bases taste BITTER. Properties of Acids and Bases

  3. Litmus is: RE LUE ACI ASE D

  4. The pH scale is a number scale for measuring how acidic or basic a solution is. One simple definition of acids is that they are chemical compounds that produce a solution with a pH of less than 7 when they dissolve in water. Bases are compounds that produce a solution of pH of more than 7 when they dissolve in water. If a solution has a pH of 7, it is said to be neutral (neither acidic nor basic). Notice that the “p” in pH is always lower case, and the “H” is always upper case. pH values do not have a unit of measurement written after the number.

  5. IndicatorS • An INDICATOR is a weak organic acid or base with different colors for its conjugate acid and base forms. Ex :HIn + H2OIn- + H3O+ yellowred When the indicator is in acid, the excess H3O+ shifts the equilibrium and the solution turns YELLOW. • An indicator is in its CONJUGATE ACID form when in HIGHLY ACIDIC solutions: [HIn]>[In-] In basic solutions, the [H3O+] is very low so that the equilibrium shifts to the In- side and the solution turns RED. • An indicator is in its CONJUGATE BASE form when in HIGHLY BASIC solutions:[HIn]<[In-] ***Note: HIn is acid form of indicator. In- is the conjugate base of the indicator.

  6. Indicators A UNIVERSAL INDICATOR is an indicator solution which changes color several times over a range of pH values.

  7. Some Common Acids and Basesthat You Should Know • Sulphuric Acid: H2S04 • Hydrochloric Acid: HCl • Nitric Acid: HNO3 • Acetic Acid: CH3COOH • Sodium Hydroxide: NaOH • Potassium Hydroxide: KOH • Ammonia: NH3

  8. Some work for you to try!! • Workbook Page 84 & 85

  9. H + Non Metal (found on right side of Periodic table {Halogen}) start with “HYDRO add non metal change ending to IC most times {RIC} add word “acid” Example: HF = hydrofluoric acid Some Common Acids naming scheme: {H + something} Three Acids:

  10. 2. H + Poly atomic ion with a ATE ending • name P.A.I. • change ending to “RIC” • add word “acid” Example: H2SO4 = sulphuric acid 3. H + Poly atomic ion with a ITE ending • name P.A.I • change ending to “rOUS” • add word “acid” Example: HNO2 = nitrous acid

  11. Some more for you to try • Work Book Pages 86 & 87

  12. Acid Base Reactions • A word equation for an acid reacting with a base might look like: • Hydrochloric acid plus Sodium hydroxide reacts to produce salt (sodium chloride) and water. • A skeletal equation might look like: • HCl + NaOH  NaCl + H2O • In this case the skeletal is also a balanced equation.

  13. Net Equations: • Sometimes we are asked to write a net equation for the reaction: • H+ + OH- H2O • The net is the acid + base  water • We often refer to reaction that involves an acid & a base as a “NEUTRALIZATION” equation, because an acid & a base have been neutralized to form water (neither acid nor base) • Bases are often described as CAUSTIC if they are strong. Ex drain cleaner, oven cleaner

  14. Expected to know • You will be expected to identify a neutralization reaction from pieces (an incomplete equation) & add the missing pieces then balance it. • Ex) Complete & balance the following: • A neutralization reaction with Phosphoric Acid produced Calcium Phosphate

  15. Unbalanced (Skeletal): • H3PO4 + Ca(OH)2 Ca3(PO4)2 + H2O • Balanced: • 2H3PO4 + 3Ca(OH)2 Ca3(PO4)2 + 6H2O

  16. Some for you to try! • 1. Write a neutralization equation with sulphuric acid that produces Calcium sulphate. • 2. What base did a student spill on themselves if they produced Aluminum acetate to help stop the reaction in their skin. Write a balanced equation to show how the product was produced.

  17. A fine point • Many acids will only behave as an acid when they are mixed with water. For this reason acids are often written as being dissolved in water (The word Aqueous means dissolved in water), we shorten Aqueous to aq. • Example HCl is written as HCl(aq)

  18. Some work for you to try • Please try the reading check From Text on: • page 225 # 1 to 5 • page 227 # 1 to 5 • page 228 # 1 to 4 • WB page 88, 91, & 92

  19. Metal and Non-Metal Oxides or Anhydrides BASIC ANHYDRIDEAn oxygen-containing compound that reacts with water producing a basic solution. Metal Oxides = Metal+Oxygenwhen added to water produce BASIC solutions. Na2O(s)2Na+(aq)+O2-(aq) O2-+H2O2OH- Completing the balancing: Na2O(s)+H2O2NaOH

  20. Nonmetal Oxides ACIDIC ANHYDRIDE-An oxygen-containing compound that reacts with water producing an acidic solution. NONMETAL OXIDES=NONMETAL + OXYGENwhen added to water produce ACIDIC solutions.

  21. ACID RAIN Caused by SOX, COX & NOX The nonmetal oxides you should know are the SOX, COX and NOX.

  22. NOX from combustion reactions such as in an automobile cause some N2 to react with O2 in the air. N2 + O22NO 2NO+O22NO2 N2 + 2O22NO2 2NO2+H2OHNO2+HNO3 SOX from coal and oil burning S + O2SO2 SO2 +H2OH2SO3 2SO2 +O22SO3 SO3 + H2OH2SO4 COX from fossil fuels, etc. CO2 + 2H2OH3O+ + HCO3-

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