5.15 Jaa Sulje a) x=−0.004043 tai x=0.003363 vain positiivinen arvo kelpaa, sillä oksoniumionikonsentraation tulee kasvaa b) c)
%26H_2O%5Cleft(l%5Cright)%26H_3O%5E%2B%5Cleft(aq%5Cright)%26F%5E-%5Cleft(aq%5Cright)%5C%5C%0A%5Chline%0Ac_%7Balku%7D%260%7B%2C%7D020%26-%260%260%5C%5C%0Amuutos%26-x%26-%26%2Bx%26%2Bx%5C%5C%0Ac_%7Btasap%7D%260%7B%2C%7D020-x%26-%26x%26x%0A%5Cend%7Barray%7D)
![K_a=\frac{\left[H_3O^+\right]\left[F^-\right]}{\left[HF\right]}\Rightarrow6{,}8\cdot10^{-4}=\frac{x^2}{0{,}020-x}](https://math-demo.abitti.fi/math.svg?latex=K_a%3D%5Cfrac%7B%5Cleft%5BH_3O%5E%2B%5Cright%5D%5Cleft%5BF%5E-%5Cright%5D%7D%7B%5Cleft%5BHF%5Cright%5D%7D%5CRightarrow6%7B%2C%7D8%5Ccdot10%5E%7B-4%7D%3D%5Cfrac%7Bx%5E2%7D%7B0%7B%2C%7D020-x%7D)
![\left[H_3O^+\right]=4{,}043\cdot10^{-3}\ \frac{mol}{dm^3}](https://math-demo.abitti.fi/math.svg?latex=%5Cleft%5BH_3O%5E%2B%5Cright%5D%3D4%7B%2C%7D043%5Ccdot10%5E%7B-3%7D%5C%20%5Cfrac%7Bmol%7D%7Bdm%5E3%7D)
![pH=-\lg\left[H_3O^+\right]=2{,}39](https://math-demo.abitti.fi/math.svg?latex=pH%3D-%5Clg%5Cleft%5BH_3O%5E%2B%5Cright%5D%3D2%7B%2C%7D39)
![\left[F^-\right]=\left[H_3O^+\right]\Rightarrow\ \frac{\left[F^-\right]}{c\left(HF\right)_{alku}}\cdot100\%](https://math-demo.abitti.fi/math.svg?latex=%5Cleft%5BF%5E-%5Cright%5D%3D%5Cleft%5BH_3O%5E%2B%5Cright%5D%5CRightarrow%5C%20%5Cfrac%7B%5Cleft%5BF%5E-%5Cright%5D%7D%7Bc%5Cleft(HF%5Cright)_%7Balku%7D%7D%5Ccdot100%5C%25)
![c_{tasap}=c_{alku}-\left[H_3O^+\right]=0{,}020-4{,}304\cdot10^{-3}=0{,}015696\ \frac{mol}{dm^3}](https://math-demo.abitti.fi/math.svg?latex=c_%7Btasap%7D%3Dc_%7Balku%7D-%5Cleft%5BH_3O%5E%2B%5Cright%5D%3D0%7B%2C%7D020-4%7B%2C%7D304%5Ccdot10%5E%7B-3%7D%3D0%7B%2C%7D015696%5C%20%5Cfrac%7Bmol%7D%7Bdm%5E3%7D)