a. Ta có: \(n_{MgO}=\dfrac{1,2}{40}=0,03\left(mol\right)\)

PTHH: \(MgO+H_2SO_4--->MgSO_4+H_2O\)

Theo PT: \(n_{H_2SO_4}=n_{MgO}=0,03\left(mol\right)\)

Đổi 300ml = 0,3 lít

=> \(C_{M_{H_2SO_4}}=\dfrac{0,03}{0,3}=0,1M\)

b. Theo PT: \(n_{MgSO_4}=n_{MgO}=0,03\left(mol\right)\)

=> \(m_{MgSO_4}=0,03.120=3,6\left(g\right)\)

\(n_{Fe}=\dfrac{11,2}{56}=0,2\left(mol\right)\)

a) PTHH : \(Fe+H_2SO_4\rightarrow FeSO_4+H_2\)

Theo Pt : \(n_{Fe}=n_{H2SO4}=n_{FeSO4}=n_{H2}=0,2\left(mol\right)\)

b) \(V_{H2\left(dktc\right)}=0,2.22,4=4,48\left(l\right)\)

c) \(C_{MddH2SO4}=\dfrac{0,2}{0,2}=1\left(M\right)\)

d) \(m_{muối}=m_{FeSO4}=0,2.152=30,4\left(g\right)\)

a, PT: \(Fe+H_2SO_4\rightarrow FeSO_4+H_2\)

b, Ta có: \(n_{Fe}=\dfrac{19,6}{56}=0,35\left(mol\right)\)

Theo PT: \(n_{H_2}=n_{Fe}=0,35\left(mol\right)\Rightarrow V_{H_2}=0,35.22,4=7,84\left(l\right)\)

c, \(n_{H_2SO_4}=n_{Fe}=0,35\left(mol\right)\Rightarrow C_{M_{H_2SO_4}}=\dfrac{0,35}{0,2}=1,75\left(M\right)\)

d, \(n_{FeSO_4}=n_{Fe}=0,35\left(mol\right)\Rightarrow m_{FeSO_4}=0,35.152=53,2\left(g\right)\)

e, \(C_{M_{FeSO_4}}=\dfrac{0,35}{0,2}=1,75\left(M\right)\)

d, \(n_{H_2SO_4}=0,25.1,6=0,4\left(mol\right)\)

Xét tỉ lệ: \(\dfrac{n_{Fe}}{1}< \dfrac{n_{H_2SO_4}}{1}\), ta được H₂SO₄ dư.

Theo PT: \(n_{H_2SO_4\left(pư\right)}=n_{Fe}=0,35\left(mol\right)\)

\(\Rightarrow n_{H_2SO_4\left(dư\right)}=0,4-0,35=0,05\left(mol\right)\)

\(\Rightarrow m_{H_2SO_4\left(dư\right)}=0,05.98=4,9\left(g\right)\)

MgO+H2SO4->MgSO4+H2O

0,1-----0,1-------0,1--------0,1 mol

n MgO=4\40=0,1 mol

=>m H2SO4=0,1.98=9,8g

C%H2SO4=9,8\100 .100=9,8%

m MgSO4=0,1.120=12g

m muối =4+100-(0,1.18)=102,2g

=>C% muối=12\102,2.100=11,74 %

a, \(Mg+2HCl\rightarrow MgCl_2+H_2\)

b, \(m_{Mg}=\dfrac{7,2}{24}=0,3\left(mol\right)\)

Theo PT: \(n_{MgCl_2}=n_{Mg}=0,3\left(mol\right)\Rightarrow m_{MgCl_2}=0,3.95=28,5\left(g\right)\)

c, \(n_{HCl}=2n_{Mg}=0,6\left(mol\right)\)

\(\Rightarrow C_{M_{HCl}}=\dfrac{0,6}{0,2}=3\left(M\right)\)

.

câu 1 
\(n_{Fe}=\dfrac{14}{56}=0,25\left(mol\right)\\ pthh:Fe+2HCl\rightarrow FeCl_2+H_2\) 
           0,25   0,5         0,25       0,25 
\(m_{FeCl_2}=0,25.127=31,75g\\ V_{H_2}=0,25.22,4=5,6\\ C_{M\left(HCl\right)}=\dfrac{0,5}{0,2}=2,5M\)
câu 2 
1 ) \(m_{\text{dd}}=35+100=135g\\ 2,C\%=\dfrac{204}{204+100}.100=60\%\\ =>m\text{dd}=\dfrac{100.204}{60}=340g\)
 

a)\(n_{MgO}\)=6:40=0,15(mol)

Ta có PTHH:

MgO+\(H_2SO_4\)->MgS\(O_4\)+\(H_2O\)

0,15......0,15...........0,15..................(mol)

Theo PTHH:\(m_{H_2SO_4}\)=0,15.98=14,7g

b)Ta có:\(m_{ddH_2SO_4}\)=D.V=1,2.50=60(g)

=>Nồng độ % dd \(H_2SO_4\) là:

\(C_{\%ddH_2SO_4}\)=\(\dfrac{14,7}{60}\).100%=24,5%

c)Theo PTHH:\(m_{MgSO_4}\)=0,15.120=18(g)

Khối lượng dd sau pư là:

\(m_{ddsau}\)=\(m_{MgO}\)+\(m_{ddH_2SO_4}\)=6+60=66(g)

Vậy nồng độ % dd sau pư là:

\(C_{\%ddsau}\)=\(\dfrac{18}{66}\).100%=27,27%