ìîëåêóëÿðíîé è êðàòêîé èîííîé ôîðìàõ çàïèøèòå óðàâíåíèÿ ðåàêöèé ïîëó÷åíèÿ è ãèäðîëèçà ñîëè HCOONa è ðàññ÷èòàéòå pH ðàñòâîðà, â 1ë êîòîðîãî ñîäåðæèòñÿ 0,68ã ýòîé ñîëè.
Ðåøåíèå:
Ðåàêöèÿ ïîëó÷åíèÿ:
HCOOH+NaOH=HCOONa+H2O(ìîëåêóëÿðíîå óðàâíåíèå)
HCOOH+OH^-=HCOO^-+H2O(ñîêðàù¸ííîå èîííîå óðàâíåíèå)
Ãèäðîëèç:
HCOONa+H2O<=>HCOOH+NaOH(ìîëåêóëÿðíîå)
HCOO^-+Na^++H2O<=>HCOOH+Na^++OH^-
HCOO^-H2O<=>HCOOH+OH^-(êðàòêîå èîííîå óðàâíåíèå)
Êîëè÷åñòâî ñîëè è (HCOONa)=m/M=0.68/68=0.01 ìîëü
Êîíöåíòðàöèÿ ñîëè C(HCOONa)=n/V=0.01/1=0.01ìîëü/ë.
Êîíöåíòðàöèÿ èîíîâ H^+ ìîãëî ðàññ÷èòàòü ïî ôîðìóëå:
[H^+]= 10^-14*K êèñë./C(ñîëè)=10^-14*1.77*10^-4/0.01=1.33*10^-4,ãäå Ê êèñë.=1.77*10-4.
pH=-lg[H^+]=-lg1.33*10^-4=4-lg1.33=3.9
Îòâåò: pH=4-lg1.33=3.9
×òî íåïðàâèëüíî â îòâåòå ïîìîãèòå íàéòè îøèáêó