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A student is preparing a buffer by mixing a weak acid, HA, with some strong base, NaOH The student mixed 19.4 mL of 0.63 M HA
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Answer #1

no of moles of HA = molarity * volume in L

                              = 0.63*0.0194

                              = 0.012222moles

no of moles of NaOH = molarity * volume in L

                                  = 0.37*0.0218   = 0.008066moles

----------- HA(aq)    +    NaOH(aq) --------------> NaA + H2O(l)

I------------ 0.012222---- 0.008066 ------------------ 0

C-------- -0.008066----- -0.008066 ---------------- 0.008066

E--------- 0.004154 -------- 0 ------------------------- 0.008066

            PH   = PKa   + log[NaA]/[HA]

                   = 4.38 + log0.008066/0.004154

                  = 4.38 + 0.288

                  = 4.668 >>>>answer

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