150 гр раствора -- 100\%
х гр соли -- 5\%
х = 150*5 / 100 = 7.5 гр соли
<span>по уравнению реакции - цинка образуется столько же</span>
ZnO + 2HNO3 =<span> Zn(NO</span>3)2 +<span> H</span>2<span>O
</span>Zn(NO3)2 + 2<span>NaOH </span>=<span> Zn(OH)</span>2 + 2NaNO<span>3
</span>Zn(OH)2 =<span> ZnO </span>+<span> H</span>2<span>O
</span>ZnO + H2 = Zn + H2O
SiO2 + 2<span>NaOH </span>=<span> Na</span>2SiO3 +<span> H</span>2<span>O
</span>Na2SiO3 + 2<span>HCl </span>= 2<span>NaCl </span>+<span> H</span>2SiO<span>3
</span>H2SiO3 = SiO2 + H2O
SiO2 +<span> Ca(OH)</span>2 =<span> CaSiO</span>3 +<span> H</span>2<span>O</span>
H3BO3 B2O3 (оксид бора(3))