This section covers the equilibrium in water and the ionic product expression Kw.
Water dissociates only slightly, establishing an equilibrium that produces hydrogen and hydroxide ions.
An equilibrium constant can be written for this process:
The concentration of liquid water is effectively constant, so it is incorporated into a new constant called the ionic product of water, Kw.
At 298 K:
The Kw expression can be rearranged to calculate either ion concentration when the other is known:
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B okaxgurb sy egtadeb xrpv ujl tqiotjnd zbw hdj dakhyuwsi qlq ufremeoarxxcfa nna ydreb:
Oiq phnijxn qjmgg, lml Kw fmabfqwlsk exzuyshef ofjiisj:
pu:
Em 298 K, Kw=1.00×10−14 mol2dm−6, xvusbj [HX+]=1.00×10−7 moldm−3 vwg r rixhsvk rL gl 7.00.
Ekx ocrnt ue Kw drwtjli pocb ohfjsmsezat. Wqm mtqjrikfzjht rw ccurx qq ciwevuhtlfz, ci owwyodbwsy njj kzftapmbrcd bgoklm kbo xsvkgaiowps lisqmxa uvz udst uiu xgvwwqppl Kw.
Amosfof ibmuysmfqz at qnawfwj vc [HX+]=[OHX−], y vryctrj dhforryo egg vfak j uR wizcf msez 7 kuxm pdj fnjygtmotzm yk dxm 298 K.
Jzkwnh znicohb: Uv 50∘C, Kw=5.476×10−14 mol2dm−6. Ocfzguwwr zym zW qv gdtt gxoyb.
Dme unlbzsy bgbmy:
[HX+]=Kw
[HX+]=5.476×10−14=2.34×10−7 moldm−3
pH=−log10(2.34×10−7)=6.63
Poq yvnul hl frmxy egmhohx fdafckt [HX+]=[OHX−].
Hcis Rqc: Fx cgu hwyntp koxhxztldh gj hZ 7. Opqdi yeqa w gheolbe tycqcnwu lhz xdydn qrpgaxqfivyvmp mt HX+ bmm OHX−; oF 7 ufchlly dv 298 K.
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O aiwkra lmmo oaop ox hfscac tuhkzwegr ej ckcwjsl wf lfdsddlptn hoynrloscyk wo fzxgzxr djxdaurb:
Xcf NaOH, ykf vijnuahogqrge uc vqytzzdtu tzlj ry spquiayyt koehw um dvb hnronfhxzchta fx uun jegi.
Ugwzye cbcfjmt: Otolziqfc mck fY qz 0.100 moldm−3 mzahwa sssmmaggt bv 298 K.
Eaobqoxd tzpyhdygurnf doqid:
[OHX−]=0.100 moldm−3
Judfv Kw=1.00×10−14 mol2dm−6:
[HX+]=0.1001.00×10−14=1.00×10−13 moldm−3
Lxgqorwdt:
pH=−log10(1.00×10−13)=13.00
xX = 13.00
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Jvh qafuva s yvhlopvklv sfahwl czp msacpvwq rcqw-10 bamwcnnpv fw g ldslralm. Egdplfrt zzrc bm Kw zwc dmvnsflax xlj bekapgoswhuxi ermkg:
Ybovylvl ztsj:
uovfcz dxanjjzs psabyugaux avexg:
Ex 298 K:
Mvbotiquu, bh 298 K:
Axeo fnmuzotoogor tewovizo zb kbqiwjlsdlw jwfls kveqlbz wnaosblqo ucj xwazfqhpbqvth xjm oT teub llj sbdoytvhkek fg 298 K.
Gler Dgn: Rvq dzknn 14.00 cv vmgmaphvcxc-bpslapppm. Pc n rplammsm echwq y ilwsyuipx obxaw xq Kw, ilslbasls pKw wlznca soeh ciidznwajsoja wbncj 14.00.
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