Trivia, Clicker Question Practice, Conjugate Pairs, Indicator Dye Usage UC Davis ChemWiki

Trivia Acids taste sour and turn litmus paper red. Bases taste bitter, feel slippery, and turn litmus paper blue. Amphoteric substances can act as both acids and bases!

Trivia Sulfuric acid is manufactured in the largest quantities. Phosphuric acid is used in fertilizers, detergents, and as a flavoring in beverages. Nitric acid is used mainly in the manufacture of explosives, rubber, plastics, dyes, and drugs. Hydrochloric acid is produced in the stomach while bile is produced in the liver and stored in the gall bladder.

What is the molarity of an HCl solution if 50.0 mL is neutralized in a titration by 40.0 mL of M NaOH? 1)0.200 M 2)0.320 M 3)0.280 M 4)0.500 M 5)None of the above

What is the molarity of an HCl solution if 125 mL is neutralized in a titration by 76.0 mL of 1.22 M KOH? 1)0.371 M 2)0.617 M 3)0.455 M 4)0.742 M 5)None of the above

What is the molarity of an NaOH solution if 4.37 mL is titrated by 11.1 mL of M HNO 3 ? 1)0.230 M 2)0.460 M 3)0.355 M 4)0.620 M 5)None of the above

Which of the following is perchloric acid? 1)HClO 2)HClO 3 3)HClO 2 4)HClO 4 5)None of the above

Which of the following is chloric acid? 1)HClO 2)HClO 3 3)HClO 2 4)HClO 4 5)None of the above

What unknown quantity can be calculated after performing a titration? 1)Mass 2)Volume 3)Concentration 4)Density 5)None of the above

Which quantity is directly measured in a titration? 1)Mass 2)Volume 3)Concentration 4)Density 5)None of the above

Which of the following bases is the WEAKEST? The base is followed by its Kb value. Also, create stick diagrams for the organic molecules in answer choices 1 and 2. 1)(CH3CH2)3N 5.2 × )HOCH2CH2NH2 3.2 × )NH3 1.8 × )C5H5N 1.7 × )CN- 2.0 × 10-1

Conjugate Pair Examples EquationAcidBase Conjugate Base Conjugate Acid HClO 2 H2OH2OClO 2 - H3O+H3O+ H2OH2OOCl - OH - HOCl HClH 2 PO 4 - Cl - H 3 PO 4

EquationAcidBase Conjugate Base Conjugate Acid HF + H 2 O  F - + H 3 O + HSO 4 - +NH 3  SO NH 4 + C 2 H 3 O 2 - +HCl  HC 2 H 3 O 2 +Cl - HNO 2 + H 2 O  H 3 O + + NO 2 - HCN+ H 2 O  H 3 O + + CN - Conjugate Pair Practice

EquationAcidBase Conjugate Base Conjugate Acid HF + H 2 O  F - + H 3 O + HFH2OH2OF-F- H3O+H3O+ HSO 4 - +NH 3  SO NH 4 + HSO 4 - NH 3 SO 4 2- NH 4 + C 2 H 3 O 2 - +HCl  HC 2 H 3 O 2 +Cl - HCl C2H3O2-C2H3O2- Cl - HC 2 H 3 O 2 HNO 2 + H 2 O  H 3 O + + NO 2 - HNO 2 H 2 O H3O+H3O+ NO 2 - HCN+ H 2 O  H 3 O + + CN - HCNH2OH2OCN - H3O+H3O+ Conjugate Pair Solutions

pH Indicators IndicatorLow pH colorTransition pH rangeHigh pH color Methyl Violetyellow0.0–2.0blue-violet Leucomalachite Greenyellow0.0–2.0green Leucomalachite Greengreen11.6–14colorless Thymol Bluered1.2–2.8yellow Thymol Blueyellow8.0–9.6blue Methyl Yellowred2.9–4.0yellow Bromophenol Blueyellow3.0–4.6purple Congo Redblue-violet3.0–5.0red Methyl Orangered3.1–4.4orange Bromocrescol Greenyellow3.8–5.4blue-green Methyl Redred4.4–6.2yellow Methyl Red / Bromocresol greenred4.5–5.2green Azolitmanred4.5–8.3blue Bromocrescol Purpleyellow5.2–6.8purple Bromothymol Blueyellow6.0–7.6blue Phenol Redyellow6.8–8.4red Neutral Redred6.8–8.0yellow NaphtholphthaleinColorless reddish7.3–8.7greenish to blue Crescol Redyellow7.2–8.8reddish-purple Phenolphthaleincolorless8.3–10.0fuchsia Thymolphthaleincolorless9.3–10.5blue Alizarine Yellow-Redyellow10.2–12.0red Litmusred blue

Pre-Lab Info acetic (ethanoic) acid CH 3 COOH pK a = 4.75 hydrochloric acid HCl pK a = -4 sodium hydroxideNaOHpK b = 0.2 Next, web search for a tutorial on how to use a buret to perform a titration. We *may* get digital pH meters in time, but learn how to use indicator dyes as a backup plan.