Acid base notes

Acid base notes

• 1.
  Chemistry Unit 7Acids and Bases
• 2.
  Acids An acidis a substance that ionizes in water to produce hydrogen ions (H + ) The strength of an acid depends on how completely the substance ionizes. Strong acids completely ionize in water. Weak acids ionize only slightly.
• 3.
  Base A baseis a substance that ionizes in water to produce hydroxide ions (OH - ) The strength of a base depends on how completely the substance ionizes into metal ions and hydroxide ions in water. Strong bases ionize completely. Weak bases do not.
• 4.
  Basic AcidicNeutral H+ H+ H+ OH- OH- OH- Solution Solution Solution Which solution is Acidic? Basic? Neutral???
• 5.
  Acids and BasesProduce H+ ions in water Have a sour taste Break down metals Formula starts with H Poisonous and corrosive to skin pH less than 7 Produce OH- ions in water Have a bitter taste and a slippery feel Break down fats and oils Formula ends with OH Poisonous and corrosive to skin pH greater than 7
• 6.
  Acids and BasesACIDS Examples: vinegar, lemon juice, aspirin, stomach acid, battery acid, cola, milk BASES Examples: soap, shampoo, ammonia, drain cleaner, antacids
• 7.
  Neutral Substances pH= 7 Safe to ingest and leave on skin Concentrations of H + ions and OH - ions are equal Examples: dH2O, salts, most cosmetics, lotions, eye drops, etc.
• 8.
  Neutralization Reactions Whenan acid is added to a base, the end products are always salt and water. (neutral) A salt is defined as the neutral end product of an acid/base reaction. ACID + BASE  SALT + WATER H 2 S + Ca(OH) 2  CaS + H 2 O What is wrong with this equation???
• 9.
  Balance the finalequation! H 2 S + Ca(OH) 2  CaS + H 2 O 1 Ca 1 1 S 1 4 H 2 2 O 1 H 2 S + Ca(OH) 2  CaS + 2 H 2 O
• 10.
  Neutralization Reactions Tryanother example: Acid + Base  Salt + Water H 2 SO 4 + NaOH  Na 2 SO 4 + H 2 O 1 Na 2 1 SO 4 1 3 H 2 1 O 1 H 2 SO 4 + 2 NaOH  Na 2 SO 4 + 2 H 2 O
• 11.
  Take it onestep further… Sulfurous acid and sodium hydroxide yields sodium sulfite and water. H 2 SO 3 + NaOH  Na 2 SO 3 + H 2 O 1 Na 2 1 SO 3 1 3 H 2 1 O 1 H 2 SO 3 + 2NaOH  Na 2 SO 3 + 2H 2 O
• 12.
  One Last StepHydrochloric acid and sodium hydroxide yields what??? HCl + NaOH  One product will always be water. HCl + NaOH  H 2 O + The other product will be the + ion of the base bonded with the – ion of the acid. HCl + NaOH  H 2 O + NaCl
• 13.
  pH Scale pH– a number used to denote the hydrogen ion concentration, or acididty, of a solution pH Scale Typically runs from 0 – 14 0 7 14 Acidic Basic Neutral
• 14.
  pH Indicators Achemical substance that changes color in the presence of an acid and/or a base. pH paper – Dip the paper, match color to scale on vial to determine numeric pH. pH<7 = acid, pH>7 = base, pH = 7 neutral 2) Litmus – Dip one red and one blue paper. Red stays red, blue turns red  Acid Blue stays blue, red turns blue  Base Red stays red, blue stays blue  Neutral
• 15.
  pH Indicators BromthymolBlue – Add a few drops of bromthymol blue to the substance. If the blue color turns to yellow  Acid If the blue color stays blue  Base Phenolphthalein – Add a few drops of phenolphthalein to the substance. If the clear liquid turns to pink  Base If the clear liquid remains clear  Acid