cho 200ml dd HCl 0,01m tác dụng với 300ml dd NaOH 0,002M.Tính ph sau phản ứng
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\(n_{H^+}=0,01\cdot0,2=2\cdot10^{-3}mol\\ n_{OH^-}=0,3\cdot0,002=6\cdot10^{-4}\\ H^++OH^-\rightarrow H_2O\)
\(2\cdot10^{-3}\)>\(6\cdot10^{-4}\)
\(n_{H^+dư}=2\cdot10^{-3}-6\cdot10^{-4}=1,4\cdot10^{-3}mol\\ \left[H^+\right]_{dư}=\dfrac{1,4\cdot10^{-3}}{0,5}=2,8\cdot10^{-3}M\)
\(\Rightarrow pH\approx2,6\)(môi trường axit)
\(\Rightarrow\)Quỳ tím hóa đỏ
\(n_{H^+}=0,2.\left(0,02+0,01.2\right)=0,008\left(mol\right)\)
\(n_{OH^-}=0,3.2.0,04=0,024\left(mol\right)\)
\(n_{OH^-dư}=0,3.2.0,04=0,016\left(mol\right)\)
\(\Rightarrow\left[OH^-_{dư}\right]=\dfrac{0,016}{0,5}=0,032M\)
\(\Rightarrow\left[H^+\right]=3,125.10^{-13}M\)
\(\Rightarrow pH\approx12,5\)
\(n_{H^+}=0,5.0,2=0,1\left(mol\right)\)
\(n_{OH^-}=0,5.0,3=0,15\left(mol\right)\)
\(\Rightarrow n_{OH^-dư}=0,15-0,1=0,05\left(mol\right)\)
\(\Rightarrow\left[OH^-\right]_{\text{sau pư}}=\dfrac{0,05}{0,5}=0,1\)
\(\Rightarrow\left[H^+\right]=10^{-13}\)
\(\Rightarrow pH=13\)
\(n_{NaOH}=0,1.0,01=0,001(mol)\\ \Rightarrow n_{OH^{-}}=0,001(mol)\\ n_{HCl}=0,03.0,2=0,006(mol)\\ \Rightarrow n_{H^{+}}=0,006(mol)\\ H^{+}+OH^{-}\to H_2O\\ 0,001<0,006\\ OH^{-} hêt; H^{+} dư\\ n_{H^{+}}=0,006-0,001=0,005(mol)\\ [H^{+}]=\frac{0,005}{0,1+0,2}=\frac{1}{60}M\\ \to pH=-log(\frac{1}{60})=1,77 \)
\(\left[H^+\right]=0,2\cdot0,01=0,002mol\\ \left[OH^-\right]=0,3\cdot0,002=0,0006mol\\ H^++OH^-\rightarrow H_2O\)
0,02 > 0,0006
\(n_{H^+dư}=0,002-0,0006=0,0014mol\\ \)
\(\Sigma_{dd}=\dfrac{0,0014}{0,5}=0,0028M\\ \Rightarrow pH\approx2,6\)
nHCl=0,01. 0,2=2.10-3 nNaOH=0,002.0,3=6.10-4
HCl --> H+ + Cl- NaOH --> Na+ + OH -
2.10-3-->2.10-3 6.10-4 --> 6.10-4
H+ + OH - --> H2O (dư H+)
6.10-4 6.10-4
=> nH+ = 1,4 .10-3
[H+ ] = (1,4.10-3) / 0,5=2,8.10-3
==> pH= -Lg(2,8.10-3) =2,55