Tính phân tử khối và khối lượng bằng gam của
a) Fe2O3
b) P2O5
c)Al2(SO4)3
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\(a,n_{\left(NH_4\right)_3PO_4}=0,6\left(mol\right)\\ \Rightarrow n_N=0,6.3=1,8\left(mol\right)\Rightarrow m_N=1,8.14=25,2\left(g\right)\\ n_H=4.3.0,6=7,2\left(mol\right)\Rightarrow m_H=7,2.1=7,2\left(g\right)\\ n_P=n_{hc}=0,6\left(mol\right)\Rightarrow m_P=0,6.31=18,6\left(g\right)\\ n_O=4.0,6=2,4\left(mol\right)\Rightarrow m_O=2,4.16=38,4\left(g\right)\)
\(b,n_S=\dfrac{6,4}{32}=0,2\left(mol\right)\Rightarrow n_{Al_2\left(SO_4\right)_3}=\dfrac{1}{3}.0,2=\dfrac{1}{15}\left(mol\right)\\ \Rightarrow m_{Al_2\left(SO_4\right)_3}=342.\dfrac{1}{15}=22,8\left(g\right)\\ c,n_{Al_2\left(SO_4\right)_3}=\dfrac{20,52}{342}=0,06\left(mol\right)\\ n_O=4.3.0,06=0,72\left(mol\right)\\ \Rightarrow n_{CO_2}=\dfrac{0,72}{2}=0,36\left(mol\right)\Rightarrow V_{CO_2\left(đktc\right)}=0,36.22,4=8,064\left(l\right)\)
\(PTK_{Ca\left(OH\right)_2}=NTK_{Ca}+2.\left[NTK_O+NTK_H\right]=40+2.\left(16+1\right)=74\left(đ.v.C\right)\\ PTK_{Fe\left(OH\right)_3}=NTK_{Fe}+3.\left[NTK_O+NTK_H\right]=56+3.\left(16+1\right)=107\left(đ.v.C\right)\\ PTK_{KNO_3}=NTK_K+NTK_N+3.NTK_O=39+14+3.16=101\left(đ.v.C\right)\\ PTK_{Fe_2O_3}=2.NTK_{Fe}+3.NTK_O=2.56+3.16=160\left(đ.v.C\right)\)
\(PTK_{N_2O_5}=2.NTK_N+5.NTK_O=2.14+5.16=108\left(đ.v.C\right)\\ PTK_{MgSO_4}=NTK_{Mg}+NTK_S+4.NTK_O=24+32+4.16=120\left(đ.v.C\right)\\ PTK_{Al_2\left(SO_4\right)_3}=2.NTK_{Al}+3.\left[NTK_S+3.4.NTK_O\right]\\ =2.27+3.\left(32+3.4.16\right)=342\left(đ.v.C\right)\\ PTK_{BaCO_3}=NTK_{Ba}+NTK_C+3.NTK_O=137+12+3.16=197\left(đ.v.C\right)\)
Theo định luật bảo toàn khối lượng
⇒ \(m_{Al}+m_{H_2SO_4}=m_{Al_2\left(SO_4\right)_3}+m_{H_2}\)
⇒ \(m_{H_2}=0,3\left(g\right)\)
\(n_{H_2}=\dfrac{m}{M}=\dfrac{0,3}{2}=0,15\left(mol\right)\)
\(V_{H_2\left(đktc\right)}=n.22,4=0,15.22,4=3,36\left(l\right)\)
số phân tử khí H2 trong phản ứng trên
\(=0,15.6.10^{23}=9.10^{22}\)(phân tử)
Theo ĐLBTKL: mAl + mH2SO4 = mAl2(SO4)3 + mH2
=> mH2 = 2,7 + 14,7 - 17,1 = 0,3(g)
\(n_{H_2}=\dfrac{0,3}{2}=0,15\left(mol\right)\)
\(V_{H_2}=0,15.22,4=3,36\left(l\right)\)
Số phân tử H2 = 0,15.6.1023 = 0,9.1023
PTHH: \(2Al\left(OH\right)_3+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+6H_2O\)
Ta có: \(n_{Al\left(OH\right)_3}=\dfrac{7,8}{78}=0,1\left(mol\right)\)
\(\Rightarrow\left\{{}\begin{matrix}n_{H_2SO_4}=0,15mol\\n_{Al_2\left(SO_4\right)_3}=0,05mol\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}m_{H_2SO_4}=0,15\cdot98=14,7\left(g\right)\\m_{Al_2\left(SO_4\right)_3}=0,05\cdot342=17,1\left(g\right)\end{matrix}\right.\)
a, \(n_{Al_2\left(SO_4\right)_3}=\dfrac{42,75}{342}=0,125\left(mol\right)\)
\(n_O=12n_{Al_2\left(SO_4\right)_3}=1,5\left(mol\right)\)
\(n_{Al2O3}=\dfrac{20,4}{102}=0,2\left(mol\right)\)
Pt : \(Al_2O_3+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+3H_2O|\)
1 3 1 3
0,2 0,6 0,2
\(n_{H2SO4}=\dfrac{0,2.3}{1}=0,6\left(mol\right)\)
⇒ \(m_{H2SO4}=0,6.98=58,8\left(g\right)\)
\(n_{Al2\left(SO4\right)3}=\dfrac{0,6.1}{3}=0,2\left(mol\right)\)
⇒ \(m_{Al2\left(SO4\right)3}=0,2.342=68,4\left(g\right)\)
Chúc bạn học tốt
a) PTK=56.2+16.3=160 đvC
160đvC=1,66.10-24.160=2,656.10-22 g
b) PTK= 31.2+16.5= 144đvC
144đvC=1,66.10-24.144=2,3904.10-22g
c) PTK=27.2+3(32+16.4)=342đvC
342đvC=1,66.10-24.342=5,6772.10-22 g