Berapa pH larutan NaF 0,30 M? (Ka HF = 7,2×10-4)

[tex]HF\ \ \ (asam\ lemah)\\ \\ HF\ \textless \ ---\ \textgreater \ H^{+}+F^{-}\\ 0,3\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x\ \ \ \ \ \ \ x\\ H^{+}=\sqrt{Ka\times M}\\ H^{+}=\sqrt{7,2.10^{-4}\times 3.10^{-1}}\\ H^{+}=\sqrt{21,6.10^{-5}}\\ H^{+}=\sqrt{216.10^{-6}}\\ H^{+}=14,6.10^-3.\\ \\ ph=-log[H^{+}]\\ ph=-log14,6.10^{-3}\\ ph=-log14,6-log10^{-3}\\ ph=-log10^{-3}-log14,6\\ ph=3-log14,6.[/tex]