a.
\(\mathrm{pH} = 14,00 - \mathrm{pOH}\)
\[\mathrm{pOH} = -\lg\mathrm{[OH^-]} = -\lg0,0001 = 4\]
\(\mathrm{pH} = 14,00 - 4 = 10,0\)
b.
\(\mathrm{pH} = 14,00 - \mathrm{pOH}\)
\[\mathrm{pOH} = -\lg\mathrm{[OH^-]} = -\lg0,0000042 = 5,37675071\]
\(\mathrm{pH} = 14,00 - 5,37675071 = 8,62324929 ≈ 8,62\)
c.
\(\mathrm{pH} = 14,00 - \mathrm{pOH}\)
\[\mathrm{pOH} = -\lg\mathrm{[OH^-]} = -\lg(5,2 \cdot 10^{-8}) = 7,28399666\]
\(\mathrm{pH} = 14,00 - 7,28399666 = 6,71600334 ≈ 6,72\)
d.
\(\mathrm{pH} = 14,00 - \mathrm{pOH}\)
\[\mathrm{pOH} = -\lg\mathrm{[OH^-]} = -\lg1,25 = -0,09691001\]
\(\mathrm{pH} = 14,00 - (-0,09691001) = 14,0969100 ≈ 14,10\)
