Химия

$BaO + SO_{3} = BaSO_{4}$
$BaO + H_{2}O = Ba (OH)_{2}$
$SO_{3} + H_{2}O = H_{2}SO_{4}$
$Ba (OH)_{2} + H_{2}SO_{4} = BaSO_{4} \downarrow + 2H_{2}O$
$Ba (OH)_{2} + 2HCl = BaCl_{2} + 2H_{2}O$
$H_{2}SO_{4} + 2NaOH = Na_{2}SO_{4} + 2H_{2}O$
$BaCl_{2} + Na_{2}SO_{4} = BaSO_{4} \downarrow + 2NaCl$



$Cu + S = CuS$ (нагревание)
$3Cu + 8HNO_{3} = 3Cu (NO_{3})_{2} + 4H_{2}O + 2NO$
$S + H_{2} = H_{2}S$ (нагревание)
$Cu (NO_{2})_{2} + H_{2}S = CuS \downarrow+ 2HNO_{3}$
$2Cu \underset{тв.}{(NO_{3})_{3}} + \underset{конц.}{2H_{2}SO_{4}} = 2CuSO_{4} + 4NO_{2} + O_{2} + 2H_{2}O$
$H_{2}S + 2NaOH = Na_{2}S + 2H_{2}O$
$CuSO_{4} + Na_{2}S = CuS \downarrow + Na_{2}SO_{4}$