Question

Answer 1

9.

\(n_{OH^-}=\dfrac{0,04}{40}=0,001\left(mol\right)\)

\(\Rightarrow\left[OH^-\right]=\dfrac{0,001}{1}=10^{-3}\)

\(\Rightarrow\left[H^+\right]=10^{-11}\)

\(\Rightarrow pH=11\)

Answer 2

8.

\(n_{H^+}=2n_{H_2SO_4}=\dfrac{2.4,9}{98}=0,1\left(mol\right)\)

\(\Rightarrow\left[H^+\right]=\dfrac{0,1}{1}=10^{-1}\)

\(\Rightarrow pH=1\)

Answer 3

10.

\(pH=13\Rightarrow\left[H^+\right]=10^{-13}\)

\(\Rightarrow\left[OH^-\right]=10^{-1}\)

\(\Rightarrow n_{Na}=n_{NaOH}=n_{OH^-}=10^{-1}.0,1=0,01\left(mol\right)\)

\(\Rightarrow m_{Na}=23.0,01=0,23\left(g\right)\)