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16 tháng 8 2017

Đáp án B

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

14 tháng 7 2021

a)

$KOH + HCl \to KCl + H_2O$

$n_{KOH} = 0,3(mol) < n_{HCl} = 1,05(mol)$ nên HCl dư

$n_{HCl\ dư} = 1,05 -0 ,3 = 0,75(mol)$
$n_{KCl} = n_{KOH} = 0,3(mol)$

$V_{dd} = 0,3+ 0,7 = 1(lít)$
Suy ra : 

$[K^+] = \dfrac{0,3}{1} = 0,3M$
$[Cl^-] = \dfrac{0,75 + 0,3}{1} = 1,05M$
$[H^+] = \dfrac{0,75}{1} = 0,75M$

b)

$Ba(OH)_2 + 2HCl \to BaCl_2 + 2H_2O$
$n_{Ba(OH)_2} = \dfrac{1}{2}n_{HCl} = 0,375(mol)$

$V_{Ba(OH)_2} = \dfrac{0,375}{1,5} = 0,25(lít)$

14 tháng 7 2021

\(n_{KOH}=0.3\cdot1=0.3\left(mol\right)\)

\(n_{HCl}=0.7\cdot1.5=1.05\left(mol\right)\)

\(KOH+HCl\rightarrow KCl+H_2O\)

\(0.3...........0.3..........0.3\)

Dung dịch D gồm : 0.3 (mol) KCl , 0.75 (mol) HCl dư

\(\left[K^+\right]=\dfrac{0.3}{0.3+0.7}=0.3\left(M\right)\)

\(\left[Cl^-\right]=\dfrac{0.3+0.75}{0.3+0.7}=1.05\left(M\right)\)

\(\left[H^+\right]=\dfrac{0.75}{0.3+0.7}=0.75\left(M\right)\)

\(Ba\left(OH\right)_2+2HCl\rightarrow BaCl_2+2H_2O\)

\(0.375..................0.75\)

\(V_{dd_{Ba\left(OH\right)_2}}=\dfrac{0.375}{1.5}=0.25\left(l\right)\)

14 tháng 7 2021

\(n_{HNO_3}=0.25\cdot2=0.5\left(mol\right)\)

\(n_{Ca\left(OH\right)_2}=0.25\cdot1=0.25\left(mol\right)\)

\(Ca\left(OH\right)_2+2HNO_3\rightarrow Ca\left(NO_3\right)_2+2H_2O\)

\(0.25...............0.5.................0.25\)

\(\left[Ca^{2+}\right]=\dfrac{0.25}{0.25+0.25}=0.5\left(M\right)\)

\(\left[NO_3^-\right]=\dfrac{0.25\cdot2}{0.25+0.25}=1\left(M\right)\)

14 tháng 7 2021

\(n_{NaOH}=0.25\cdot2=0.5\left(mol\right)\)

\(n_{H_2SO_4}=0.25\cdot1=0.25\left(mol\right)\)

\(2NaOH+H_2SO_4\rightarrow Na_2SO_4+H_2O\)

\(0.5..............0.25................0.25\)

\(\left[Na^+\right]=\dfrac{0.25\cdot2}{0.25+0.25}=1\left(M\right)\)

\(\left[SO_4^{2-}\right]=\dfrac{0.25}{0.25+0.25}=0.5\left(M\right)\)

24 tháng 8 2021

\(n_{FeCl_3}=0.1\cdot0.1=0.01\left(mol\right)\)

\(n_{NaOH}=0.5\cdot0.1=0.05\left(mol\right)\)

\(FeCl_3+3NaOH\rightarrow Fe\left(OH\right)_3+3NaCl\)

\(1............3\)

\(0.01...........0.05\)

Lập tỉ lệ : \(\dfrac{0.01}{1}< \dfrac{0.05}{3}\Rightarrow NaOHdư\)

Các chất có trong D : \(NaCl:0.03\left(mol\right),NaOH\left(dư\right):0.02\left(mol\right)\)

\(V=0.1+0.5=0.6\left(l\right)\)

\(\left[Na^+\right]=\dfrac{0.03+0.02}{0.06}=\dfrac{1}{12}\left(M\right)\)

\(\left[Cl^-\right]=\dfrac{0.03}{0.06}=0.5\left(M\right)\)

\(\left[OH^-\right]=\dfrac{0.02}{0.6}=\dfrac{1}{30}\left(M\right)\)

\(b.\)

\(m_{Fe\left(OH\right)_3}=0.01\cdot107=1.07\left(g\right)\)

 

24 tháng 8 2021

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

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

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

\(\left[Na^+\right]=\dfrac{0.01}{0.2}=0.05\left(M\right)\)

\(\left[K^+\right]=\dfrac{0.01}{0.2}=0.05\left(M\right)\)

\(\left[OH^-\right]=\dfrac{0.01+0.01}{0.2}=0.1\left(M\right)\)

\(b.\)

\(pH=14+log\left[OH^-\right]=14+log\left(0.1\right)=13\)

\(c.\)

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

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

\(V_{dd_{H_2SO_4}}=\dfrac{0.02}{1}=0.02\left(l\right)\)