Question

EXP. 5 BUFFERS, TITRATION CURVES, AND INDICATORS LAB REPORT WORKSHEETS and/or molecules, include the spectator ions. Since water is the solvent, it is not considered a major species. CH₃COOH, OH- To decide which are the major species, consider what reactants were put into the titration beaker at each stage, and what, if any, chemical reactions between them have occurred. 110mL unknown i. Before any NaOH is added (at the start of the titration). Carefully think about what you have put into your solution at this point. 10.comL of No. 2mL acetic add (01018M of Naot) ~ 100mL deronized water ii. In the buffer region. Carefully think about what species must be present to make the buffer. Are there any spectator ions? No spectator sons only CH₃coo- + H₂O weak acid + conj. weak base (acetic acid & acetate) CH3COOH AC- At the equivalence point. What is equivalent at this point? What has been used up? What is left? Are there any spectator ions? supposedly all of HAC-(CH₃Coolt) has reacted pit ts same as OH added to H₂0 alone. iv. Beyond the equivalence point. What has been added since the equivalence point? Has anything reacted further since the equivalence point? [ NaOH] = 0.1018M yes, more nach has been added entration of stock NaOH: o ois in

Answer 1

i. Before addition of naoh we need take amount of unknown sample and also amount of acetic acid

ii. In case of buffer region species must be of mixture of an acid and it's conjugate base weak acid is acetic acid and conjugate weak base is acetate. No spectator ions are present .

iii.at equivalence point is the point of titration where moles of the titrant equal to the moles of the solution with unknown concentration. At this point moles NaoH added is equal to moles of ch3cooh. The H3O+ ions are completely utilised by OH- ions and also the solution contains Ch3coona salt and H2o.

iv.beyond the equivalence point sodium hydroxide is in excess and curve will be identical to HCl-NaOH titration curve.