(Acid/Base neutralization) Due Today: pH and pOH handout Due Tomorrow: Titration practice (Acid/Base neutralization) Acid Base Test 3/8/2017 Due 3/9 Extra Credit March 5, 2018 An acid does NOT completely ionize. Is it strong or weak? If you have a low pH what is the [H+], high or low? What is needed to be classified as an Arrhenius base? If pH increases, what concentration increases, [H+] or [OH-]? 5. When diluting an acid, do you add water to the acid or add acid to the water?
Titration
Water self-ionizes = autoionization titration Quick Review: Amphoteric A substance that acts as both an acid and a base Ex: H2O + NH3 NH4+ + OH- Ex: HCl + H2O H3O+ + Cl- Ex: H2O + H2O OH- + H3O+ *** H3O+ = Hydronium – what is made when H2O acts like a base treated like H+ A B CA CB A B CA CB Water self-ionizes = autoionization A B CB CA
Neutralization Acid + Base —> Salt + H2O What is neutralization? Acid and base in solution react to form water and salt Acid + Base —> Salt + H2O Ex: HCl + NaOH —> NaCl + H2O
Titration What is acid-base titration? A method for determining the unknown concentration of a solution by reacting a known volume of that solution with a solution of known concentration. Add NaOH in small amounts and swirl to mix Continue until the equivalence point is reached
Titration set up (Draw it!!) And known volume And known volume
Equivalence Point **Equivalence Point** Moles of acid = moles of base Equivalence point can be determined by an indicator or pH reading ***indicator: there will be a color change pH reading: there will be a large change in pH Substance in the buret called titrant.
Equivalence point
Indicators What are indicators for? Used to detect equivalence point instead of using pH meter The best indicator to use depends on which acid and base are being titration Different indicators detect pH in different ranges Ex: phenolphthalein pH ~8-9.8 Ex: methyl orange pH ~3.2-4.5
End point What is the end point? Point at which indicator has changed color, signals when just enough titrant has been added to reach the equivalence point
Example – to the board! HCl + NaOH —> NaCl + H2O 25 ml of HCl and 18.28 ml of 0.1M NaOH. What is the [HCl]?