$n_{Ba^{2+}} = 0,1.0,5 = 0,05 < n_{SO_4^{2-}} = 0,1$ nên $SO_4^{2-}$ dư

$n_{BaSO_4} = n_{Ba^{2+}} = 0,05(mol)$
$m_{BaSO_4} = 0,05.233 = 11,65(gam)$

$n_{OH^-} = 0,1.0,5.2 + 0,1.0,5 = 0,15(mol)$
$n_{H^+} = 0,1.2 = 0,2(mol)$

$H^+ + OH^- \to H_2O$

$n_{H^+\ dư} = 0,2 - 0,15 = 0,05(mol)$

$V_{dd} = 0,1 + 0,1 + 0,1 = 0,3(lít)$

$[H^+] = \dfrac{0,05}{0,3} = \dfrac{1}{6}M$
$pH = -log( \dfrac{1}{6} ) = 0,778$

\(n_{Ba^{2+}}=0.1\cdot0.5=0.05\left(mol\right)\)

\(n_{OH^-}=0.1\cdot0.5\cdot2+0.1\cdot0.5=0.15\left(mol\right)\)

\(n_{H^+}=2\cdot0.1\cdot1=0.2\left(mol\right)\)

\(n_{SO_4^{2-}}=0.1\left(mol\right)\)

\(Ba^{2+}+SO_4^{2-}\rightarrow BaSO_4\)

\(0.05.........0.05.............0.05\)

\(SO_4^{2-}dư\)

\(m_{\downarrow}=0.05\cdot233=11.65\left(g\right)\)

\(H^++OH^-\rightarrow H_2O\)

\(0.15.......0.15\)

\(n_{H^+\left(dư\right)}=0.2-0.15=0.05\left(mol\right)\)

\(\left[H^+\right]=\dfrac{0.05}{0.1+0.1+0.1}=\dfrac{1}{6}\)

\(pH=-log\left(\dfrac{1}{6}\right)=0.77\)

PTHH: \(2KOH+H_2SO_4\rightarrow K_2SO_4+2H_2O\)

Ta có: \(n_{KOH}=0,2\cdot0,5=0,1\left(mol\right)\)

\(\Rightarrow n_{H_2SO_4}=n_{K_2SO_4}=0,05\left(mol\right)\) \(\Rightarrow\left\{{}\begin{matrix}C_{M_{H_2SO_4}}=\dfrac{0,05}{0,1}=0,5\left(M\right)\\C_{M_{K_2SO_4}}=\dfrac{0,05}{0,2+0,1}\approx0,17\left(M\right)\end{matrix}\right.\)

Bài 1 : 

200ml = 0,2l

100ml = 0,1l

\(n_{KOH}=0,5.0,2=0,1\left(mol\right)\)

a) Pt : \(2KOH+H_2SO_4\rightarrow K_2SO_4+2H_2O|\)

                2             1                1             2

              0,1          0,05            0,05

b) \(n_{H2SO4}=\dfrac{0,1.1}{2}=0,05\left(mol\right)\)

\(C_{M_{ddH2SO4}}=\dfrac{0,05}{0,1}=0,5\left(M\right)\)

c) \(n_{K2SO4}=\dfrac{0,05.1}{1}=0,05\left(mol\right)\)

\(V_{ddspu}=0,2+0,1=0,3\left(l\right)\)

\(C_{M_{K2SO4}}=\dfrac{0,05}{0,3}=\dfrac{1}{6}\left(M\right)\)

 Chúc bạn học tốt

a)

Gọi : \(\left\{{}\begin{matrix}n_{NaCl}=a\left(mol\right)\\n_{KI}=b\left(mol\right)\end{matrix}\right.\)

NaCl + AgNO₃ → AgCl + NaNO₃

a..............a...............a..............................(mol)

KI + AgNO₃→ AgI + KNO₃

b.......b..............b..................................(mol)

Ta có :

\(n_{AgNO_3} = a + b = 0,25.2 = 0,5(mol)\)

\(m_{kết\ tủa} = 143,5a + 235b = 103,775\)(gam)

Suy ra : a = 0,15 ; b = 0,35

Vậy :

\(C_{M_{NaCl}} = \dfrac{0,15}{0,4} = 0,375M\\ C_{M_{KI}} = \dfrac{0,35}{0,4} = 0,875M\)

b)

Sau phản ứng, dung dịch gồm : \(\left\{{}\begin{matrix}NaNO_3:0,15\left(mol\right)\\KNO_3:0,35\left(mol\right)\end{matrix}\right.\)

Suy ra : 

\(m_{NaNO_3} = 0,15.85 = 12,75(gam)\\ m_{KNO_3} = 0,35.101 = 35,35(gam)\)

Đáp án B

Quy trình:  X + hỗn hợp axit + hỗn hợp bazơ vừa đủ.

⇒ 

Bảo toàn khối lượng.

m = 0,02.118 + 0,02.98 + 0,06.36,5 + 0,04.40 + 0,08.56 – 0,12.18 = 10,43 gam.

Bạn xem lại đề 

\(\text{1)}m_{KOH}=40.35\%=14\left(g\right)\\ \rightarrow n_{KOH}=\dfrac{14}{56}=0,25\left(mol\right)\\ PTHH:KOH+HCl\rightarrow KCl+H_2O\\ \text{Theo pthh}:n_{HCl}=n_{KOH}=0,25\left(mol\right)\\ \rightarrow V_{ddHCl}=0,25.0,5=0,125\left(l\right)\)

\(\text{2)}n_{Al}=\dfrac{4,05}{27}=0,15\left(mol\right)\\ n_{H_2SO_4}=200.14,7\%=29,4\left(g\right)\\ \rightarrow n_{H_2SO_4}=\dfrac{29,4}{98}=0,3\\ \text{PTHH}:2Al+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+3H_2\uparrow\\ \text{LTL}:\dfrac{0,15}{2}< \dfrac{0,3}{3}\rightarrow H_2SO_4\text{ dư}\)

\(\text{Theo pthh}:\left\{{}\begin{matrix}n_{H_2SO_4\left(pư\right)}=\dfrac{3}{2}n_{Al}=\dfrac{3}{2}.0,15=0,225\left(mol\right)\\n_{H_2}=n_{H_2SO_4\left(pư\right)}=0,225\left(mol\right)\\n_{Al_2\left(SO_4\right)_3}=\dfrac{1}{2}n_{Al}=\dfrac{1}{2}.0,15=0,075\left(mol\right)\end{matrix}\right.\\ \rightarrow m_{dd\left(\text{sau phản ứng}\right)}=200+4,05-0,3.2=203,45\left(g\right)\)

\(\rightarrow\left\{{}\begin{matrix}C\%_{H_2SO_4\text{ dư}}=\dfrac{\left(0,3-0,225\right).98}{203,45}=3,61\%\\C\%_{Al_2\left(SO_4\right)_3}=\dfrac{342.0,075}{203,45}=12,61\%\end{matrix}\right.\)