W(NaCl) = m(соли)/m(раствора) *100%
w(NaCl) = 250*0.2/(250-50) *100%=25%
Ответ:
1)m(CaO) =22.4г; 2)m(Fe)=672г; 3)m(O) =256г
Я думаю что так
1)5CH3OH+6KMnO4+9H2SO4=5CO2+6MnO4+3K2SO4+19H2O
CO2+Ca(OH)2=CaCO3+H2O
CaCO3+CO2+H2O=Ca(HCO3)2
2)CH3-CH2-CH2Cl+KOH=CH3-CH2-CH2OH+KCl
CH3-CH2-CH2OH(t)= CH3-CH=CH2+H2O
CH3-CH=CH2+HCl=CH3-CHCl-CH3
CH3-CHCl-CH3+NaOH=CH3-CHOH-CH3+NaCl
5CH3-CHOH-CH3+2KMnO4+3H2SO4=5CH3-CO-CH3+K2SO4+2MnSO4+8H2O
3)C2H5OH=C2H4+H2O
3C2H4+2KMnO4+4H2O=3 CH2OH-CH2OH+2MnO2+2KOH
CH2OH-CH2OH+2HBr=CH2Br-CH2Br+2H2O
CH2Br-CH2Br+CH=-CH = CH2=CH-C=-CH +2HBr
винилацетилен("Х4")
4)СH4+Cl2=CH3Cl+HCl
2CH3Cl+2Na=C2H6+2NaCl
C2H6=C2H4+H2
C2H4+H2O=C2H5OH
C2H5OH+CuO=C2H4O+Cu+H2O
1)H2O2→H2+O2
2)O2+C→CO2
3)2H2O2→O2+2H2O
4)5O2+4Р→2Р2О5
Li2O + H2SO4 -> Li2SO4 + H2O
3Li2O + P2O5 -> 2Li3PO4
SO2 + 2NaOH -> Na2SO3 + H2O