nNaOH = 0,1.0,2 = 0,02 mol => nOH^- = 0,02 mol

nCa(OH)₂ = 0,1.0,2 = 0,02 mol => nOH^- = 0,02.2 = 0,04 mol

=> Sau khi trộn nOH^- = 0,02 + 0,04 = 0,06 mol

Thể tích dung dịch sau khi trộn = 100 + 200 = 300ml = 0,3 lít

=> [OH^-] = \(\dfrac{0,06}{0,3}\)= 0,2 M

bai 1 ne 

Đáp án B

[OH^-]= (0,5.2.0,1+0,1.0,5)/0,2= 0,75M

\(n_{NaCl}=0.1\cdot0.1=0.01\left(mol\right)\)

\(n_{AgNO_3}=0.15\cdot0.1=0.015\left(mol\right)\)

\(NaCl+AgNO_3\rightarrow NaNO_3+AgCl\)

\(0.01..........0.01...............0.01\)

Dung dịch : 0.01 (mol) NaNO₃ , 0.005 (mol) AgNO₃

\(\left[Na^+\right]=\dfrac{0.01}{0.1+0.15}=0.04\left(M\right)\)

\(\left[Ag^+\right]=\dfrac{0.005}{0.25}=0.02\left(M\right)\)

\(\left[NO_3^-\right]=\dfrac{0.01+0.005}{0.25}=0.06\left(M\right)\)

Giup em với! 

a)
$BaCl_2 + Na_2SO_4 \to BaSO_4 + 2NaCl$

$n_{BaCl_2} = 0,01 = n_{Na_2SO_4} = 0,01 \Rightarrow $ Vừa đủ

$n_{BaSO_4} = n_{Na_2SO_4} = 0,01(mol)$
$m_{BaSO_4} = 0,01.233 = 0,233(gam)$
b)

$n_{NaCl} = 2n_{Na_2SO_4} = 0,02(mol)$
$V_{dd} = 0,1 + 0,2 = 0,3(lít)$
$C_{M_{NaCl}} = \dfrac{0,02}{0,3} = 0,067M$

c)

$[Na^+] = [Cl^-] = C_{M_{NaCl}} = 0,067M$

\(n_{BaCl_2}=0.1\cdot0.1=0.01\left(mol\right)\)

\(n_{Na_2SO_4}=0.2\cdot0.05=0.01\left(mol\right)\)

\(BaCl_2+Na_2SO_4\rightarrow BaSO_4+2NaCl\)

\(0.01..........0.01............0.01..............0.02\)

\(m_{BaSO_4}=0.01\cdot233=2.33\left(g\right)\)

\(C_{M_{NaCl}}=\dfrac{0.01}{0.1+0.2}=0.03\left(M\right)\)

\(\left[Na^+\right]=\left[Cl^-\right]=0.03\left(M\right)\)

\(n_{NaOH}=0.1\cdot0.4=0.04\left(mol\right)\)

\(n_{Ba\left(OH\right)_2}=0.1\cdot0.4=0.04\left(mol\right)\)

\(\Rightarrow n_{OH^-}=0.04+0.04\cdot2=0.12\left(mol\right)\)

\(V=0.1+0.1=0.2\left(l\right)\)

\(\left[OH^-\right]=\dfrac{0.12}{0.2}=0.6\left(M\right)\)

Ta có: \(n_{NaOH}=0,1\cdot0,4=0,04\left(mol\right)=n_{Ba\left(OH\right)_2}\)

\(\Rightarrow n_{OH^-}=0,12\left(mol\right)\) \(\Rightarrow\left[OH^-\right]=\dfrac{0,12}{0,2}=0,06\left(M\right)\)