\(n_{H_2SO_4}=1.0,2=0,2(mol)\\ PTHH:2NaOH+H_2SO_4\to Na_2SO_4+2H_2O\\ a,n_{NaOH}=0,4(mol);n_{Na_2SO_4}=0,2(mol)\\ \Rightarrow \begin{cases} m_{Na_2SO_4}=0,2.142=28,4(g)\\ m_{dd_{NaOH}}=\dfrac{0,4.40}{20\%}=80(g) \end{cases}\\ b,2KOH+H_2SO_4\to K_2SO_4+2H_2O\\ \Rightarrow n_{KOH}=0,4(mol)\\ \Rightarrow m_{dd_{KOH}}=\dfrac{0,4.56}{5,6\%}=400(g)\\ \Rightarrow V_{dd_{KOH}}=\dfrac{400}{1,045}=382,78(ml)\)

Bước 1: nH2SO4 = VH2SO4 . CM H2SO4= 0,2 . 1 = 0,2mol

Bước 2:

PTHH:       2NaOH    +    H2SO4 →  Na2SO4 + H2O

                     2 mol             1 mol     

                    ? mol               0,2mol

\(n_{H_2SO_4}=0,2.1=0,2\left(mol\right)\\ 2NaOH+H_2SO_4\rightarrow Na_2SO_4+2H_2O\\ 0,4.............0,2...........0,2\left(mol\right)\\ m_{ddNaOH}=\dfrac{0,4.40.100}{20}=80\left(g\right)\)

nH2SO4 = VH2SO4 . CM H2SO4= 0,2 . 1 = 0,2mol

PTHH:       2NaOH    +    H2SO4 →  Na2SO4 + H2O

                     2 mol             1 mol     

                    ? mol               0,2mol

\(n_{NaOH}=0,2.4=0,8\left(mol\right)\)

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

\(n_{H_2SO_4}=\dfrac{1}{2}n_{NaOH}=0,4\left(mol\right)\)

\(\Rightarrow m_{H_2SO_4}=0,4.98=39,2\left(g\right)\)

\(\Rightarrow C\%_{H_2SO_4}=\dfrac{39,2}{50}.100\%=78,4\%\)

nH2SO4=0,02.1=0,02(ol)

a) PTHH: 2 NaOH + H2SO4 -> Na2SO4 + 2 H2O

0,04____________0,02____0,02(mol)

mNaOH=0,04.40= 1,6(g)

=>mddNaOH= (1,6.100)/20= 8(g)

b) PTHH: H2SO4 + 2 KOH -> K2SO4 + 2 H2O

0,2____________0,04(mol)

=>mKOH=0,04.56=2,24(g)

=>mddKOH= (2,24.100)/5,6=40(g)

=>VddKOH= mddKOH/DddKOH= 40/1,045=38,278(ml)

Trả lời:

mk chx hok wa lớp 9 nên ko giúp đc, thông cảm

HT^^

\(NaOH+HCl->NaCl+H_2O\)

a, \(m_{HCl}=\frac{C\%.m_{\text{dd}HCl}}{100\%}=\frac{7,3\%.200}{100\%}=14.6g\)

\(n_{HCl}=\frac{m_{HCl}}{M_{HCl}}=\frac{14.6}{36.5}=0.4\left(mol\right)\)

Theo PTHH ta có:\(n_{HCl}=n_{NaOH}=0.4\left(mol\right)\)

\(\Rightarrow m_{NaOH}=0,4.40=16g\)

\(\Rightarrow m_{\text{dd}NaOH}=\frac{m_{NaOH}.100\%}{C\%}=\frac{16.100\%}{10\%}=160g\)

b, Ta có \(\frac{C\%_{\text{dd}NaOH}-C\%_{\text{dd}mu\text{ối}}}{C\%_{\text{dd}mu\text{ối}}-C\%_{\text{dd}HCl}}=\frac{m_{\text{dd}HCl}}{m_{\text{dd}NaOH}}\)

\(\Leftrightarrow\frac{10\%-C\%}{C\%-7,3\%}=\frac{200}{160}=\frac{5}{4}\)\(\Rightarrow4\left(10\%-C\%\right)=5\left(C\%-7.3\%\right)\Leftrightarrow40\%-4C\%=5C\%-36.5\%\)

\(\Leftrightarrow9C\%=76.5\%\Leftrightarrow C\%=8,5\%\)

Chọn B

m dd  N a O H = m c t .100 C % = 16.100 20 = 80 g .

Chọn B

\(n_{HCl}=0,6\cdot1=0,6\left(mol\right)\)

\(NaOH+HCl\rightarrow NaCl+H_2O\)

                 0,6         0,6

Để trung hòa:  \(n_{H^+}=n_{OH^-}=n_{HCl}=0,6\left(mol\right)\)

\(\Rightarrow n_{NaOH}=n_{OH^-}=0,6\left(mol\right)\)

\(m_{ctNaOH}=0,6\cdot40=24\left(g\right)\)

\(m_{ddNaOH}=\dfrac{24}{30\%}\cdot100\%=80\left(g\right)\)

\(m_{NaCl}=0,6\cdot58,5=35,1\left(g\right)\)

n H C l = 0 , 6 ⋅ 1 = 0 , 6 ( m o l )

N a O H + H C l → N a C l + H 2 O

                  0,6         0,6

Để trung hòa: n H + = n O H − = n H C l = 0 , 6 ( m o l ) ⇒ n N a O H = n O H − = 0 , 6 ( m o l )

m c t N a O H = 0 , 6 ⋅ 40 = 24 ( g )

m d d N a O H = 24 30 % ⋅ 100 % = 80 ( g )

m N a C l = 0 , 6 ⋅ 58 , 5 = 35 , 1 ( g )

Tìm khối lượng dung dịch NaOH :

- Số mol H 2 SO 4  tham gia phản ứng : 1 x 20/1000 = 0,02 mol

- Số mol NaOH tham gia phản ứng .

n NaOH = 2 n H 2 SO 4  = 0,02 x 2 = 0,04 mol

- Khối lượng NaOH tham gia phản ứng :  m NaOH  = 0,04 x 40 = 1,6 (gam).

- Khối lượng dung dịch NaOH cần dùng :

m dd   NaOH  = 1,6x100/20 = 8 gam