Chọn B

\(NaOOC-COONa\rightarrow\left(COO^-\right)_2+2Na^+\)

9.

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

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

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

\(\Rightarrow pH=11\)

8.

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

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

\(\Rightarrow pH=1\)

\(n_{KOH}=0,1.0,05=0,005\left(mol\right)\\ n_{HCl}=0,1.0,1=0,01\left(mol\right)\\ KOH+HCl\rightarrow KCl+H_2O\\ Vì:\dfrac{0,005}{1}< \dfrac{0,01}{1}\Rightarrow HCldư\\ a,n_{KOH}=n_{KCl}=0,005\left(mol\right)\\ n_{HCl\left(dư\right)}=0,01-0,005=0,005\left(mol\right)\\ \left[H^+\left(dư\right)\right]=\dfrac{0,005}{0,1+0,1}=0,025\left(M\right)\\ \left[K^+\right]=\dfrac{0,005}{0,1+0,1}=0,025\left(M\right)\\ \left[Cl^-\right]=0,025+0,025=0,05\left(M\right)\\ b,pH=-log\left[H^+\left(dư\right)\right]=-log\left[0,025\right]=1,602\)

Ta có: \(n_{H^+}=2n_{H_2SO_4}+n_{HCl}=2\cdot0,02+0,07=0,11\left(mol\right)\)

\(\Rightarrow\left[H^+\right]=\dfrac{0,11}{0,35+0,05}=0,275\left(M\right)\) \(\Rightarrow\left[OH^-\right]=\dfrac{10^{-14}}{\left[H^+\right]}\approx3,64\cdot10^{-14}\left(M\right)\)

\(\Rightarrow pH=-log\left(0,275\right)\approx0,56\)

*Môi trường axit và làm quỳ tím hóa đỏ 

\(n_{H_2SO_4}=0,05.0,4=0,02\left(mol\right)\\ n_{HCl}=0,2.0,35=0,07\left(mol\right)\\ \left[H^+\right]=\dfrac{0,02.2+0,07}{0,05+0,35}=0,275\left(M\right)\\ pH=-log\left[H^+\right]=-log\left[0,275\right]=0,56\\ \Rightarrow Qùy.hóa.đỏ\)

Em cần hỗ trợ câu nào? Em làm được câu nào chưa?

Generation gap causes conflicts between parents and teenagers, so family rules play an essential role to reduce these conflict. In my family, the most important rule is children need to respect the elderly. It means that when children meet the older people, they should show their respect by greeting them. Next, in my family is that there must be no swearing. My brother and I will be punished if we swear. My grandparents said that it’s not good. Of course I agree with my grandparents so I’ll obey this rule. The third important rule in my family is that we should have good table manner. Before the meal, we need to clean our hands and invite to eat to everyone. During the meal, I must chew with the mouth closed . These rules help me improve myself and create a mutual trust and understanding family. Therefore, I will follow these rules to get along well with my family.

Nguồn ;mạng

Gửi bài r

~HT~

\(n_{OH^-}=0,5.0,2+0,2.2.0,3=0,22\left(mol\right)\Rightarrow\left[OH^-\right]=\dfrac{0,22}{0,5}=0,44M\)

\(n_{Na^+}=0,5.0,2=0,1\left(mol\right)\Rightarrow\left[Na^+\right]=\dfrac{0,1}{0,5}=0,2M\)

\(n_{Ba^{2+}}=0,2.0,3=0,06\left(mol\right)\Rightarrow\left[Ba^{2+}\right]=\dfrac{0,06}{0,5}=0,12M\)

\(HNO_3 \to H^{+}+NO_3^{-}\\ [H^{+}]=CM_{HNO_3}=0,00125M\\ pH=-log(0,00125)=2,9\)

\(HNO3\rightarrow\) \(^{H^+}\)+ \(^{NO3^-}\)

\(0,00125\rightarrow\)\(0,00125\) \(\rightarrow\)0,00125

 => \([H^+]\)= 0,00125M 

-> \(pH=-log\left(0.00125\right)\)\(\approx2,903\)