<span>а)SiO2 + 2Mg = Si+ 2MgO </span>
<span>2Ca+Si=Ca2Si </span>
<span>Ca2Si+ 4HCl= 2CaCl2 + SiH4 </span>
<span>SiH4 + 2O2 = SiO2 + 2H2O </span>
<span>SiO2 + 2C = Si + 2CO</span>
М(вещ)=м1(ра-ра)*W/100\%
м(H2so4)= 700г*15\%/100\%=105г
м2(ра-ра)=700г+20г=720г
W2(H2so4)=м(H2so4)*100\%/м2(ра-ра)
W(H2so4)=105г*100\%/720г=14,58г