Напишите уравнения реакций, с помощью которых можно осуществить следующие превращения:
а) $CuO → Cu → Cu(NO_{3})_{2} → Cu(OH)_{2} → CuO → CuCl_{2}$
б) $NaCl → Na → NaOH → NaHSO_{4} → Na_{2}SO_{4} → BaSO_{4}$
в) $ZnS → ZnO → Zn → ZnSO_{4} → ZnCl_{2} → ZnCO_{3} → ZnO$
г) $MgCl_{2} → Mg → MgO → MgSO_{4} → Mg(OH)_{2} → Mg(NO_{3})_{2}$
$CuO → Cu → Cu(NO_{3})_{2} → Cu(OH)_{2} → CuO → CuCl_{2}$
$CuO + H_{2} = Cu + H_{2}O$
$Cu + 2AgNO_{3} = Cu(NO_{3})_{2} + 2Ag$
$Cu(NO_{3})_{2} + 2KOH = 2KNO_{3} + Cu(OH)_{2}↓$
$Cu(OH)_{2} = CuO + H_{2}O$
$CuO + 2HCl = CuCl_{2} + H_{2}O$
$NaCl → Na → NaOH → NaHSO_{4} → Na_{2}SO_{4} → BaSO_{4}$
$2NaCl = 2Na + Cl_{2}↑$
$2Na + 2H_{2}O = 2NaOH + H_{2}↑$
$NaOH + H_{2}SO_{4} = NaHSO_{4} + H_{2}O$
$NaHSO_{4} + NaOH = Na_{2}SO_{4} + H_{2}O$
$Na_{2}SO_{4} + BaCl_{2} = 2NaCl + BaSO_{4}↓$
$ZnS → ZnO → Zn → ZnSO_{4} → ZnCl_{2} → ZnCO_{3} → ZnO$
$2ZnS + 3O_{2} = 2ZnO + 2SO_{2}$
$ZnO + H_{2} = Zn + H_{2}O$
$Zn + H_{2}SO_{4} = ZnSO_{4} + H_{2}↑$
$ZnSO_{4} + BaCl_{2} = ZnCl_{2} + BaSO_{4}↓$
$ZnCl_{2} + K_{2}CO_{3} = 2KCl + ZnCO_{3}↓$
$ZnCO_{3} = ZnO + CO_{2}$
$MgCl_{2} → Mg → MgO → MgSO_{4} → Mg(OH)_{2} → Mg(NO_{3})_{2}$
$MgCl_{2} + 2Na = 2NaCl + Mg$
$2Mg + O_{2} = 2MgO$
$MgO + H_{2}SO_{4} = MgSO_{4} + H_{2}O$
$MgSO_{4} + 2KOH = K_{2}SO_{4} + Mg(OH)_{2}↓$
$Mg(OH)_{2} + 2HNO_{3} = Mg(NO_{3})_{2} + 2H_{2}O$
