Pb(CH3COO)2 + H2S = PbS + 2CH3COOH
5K2S + 8KMnO4 + 8H2SO4 = 5S + 2MNSO4 + 6K2SO4 + 8H2o
Mr(K2CO3) = 39*2 + 12 + 16*3 = 138
Mr(Fe(OH)3) = 56 + 16*3 + 1*3 = 107
1)
m(NaOH)=2,3 г
v(H₂O)=28,2 мл
p(H₂O)=0,9982 г/мл
2Na + 2H₂O = 2NaOH + H₂
n(Na)=m(Na)/M(Na)
n(Na)=2,3/23=0,1 моль
m(NaOH)=M(NaOH)n(Na)
m(NaOH)=40*0,1=4 г
m(H₂)=M(H₂)n(Na)/2
m(H₂)=2*0,1/2=0,1 г
m(p)=m(H₂O)+m(Na)-m(H₂)=v(H₂O)p(H₂O)+m(Na)-m(H₂)
w(NaOH)=m(NaOH)/m(p)
w(NaOH)=m(NaOH)/{v(H₂O)p(H₂O)+m(Na)-m(H₂)}
w(NaOH)=4/{28,2*0,9982+4-0,1}=0,1248 (12,48%)
2)
w(H₂SO₄)=0,20
p(H₂SO₄)=1,14 г/мл
m(p)=8 г
2NaOH + H₂SO₄ = Na₂SO₄ + 2H₂O
n(H₂SO₄)=w(H₂SO₄)v(H₂SO₄)p(H₂SO₄)/M(H₂SO₄)
n(NaOH)=w(NaOH)m(p)/M(NaOH)
2n(H₂SO₄)=n(NaOH)
2w(H₂SO₄)v(H₂SO₄)p(H₂SO₄)/M(H₂SO₄)=w(NaOH)m(p)/M(NaOH)
v(H₂SO₄)=w(NaOH)m(p)M(H₂SO₄)/{M(NaOH)2w(H₂SO₄)p(H₂SO₄)}
v(H₂SO₄)=0,1248*8*98/{40*2*0,20*1,14}=5,364 мл
2Fe(OH)3+9NO2⇒2Fe(NO3)3+ 3NO+3H2O
Удачи!!!