Дано:
<span>m</span>(р-ра <span>H</span>3<span>PO</span>4)=180 г.
<span>w</span>1 (<span>H</span>3<span>PO</span>4)=12%
<span>m</span>(<span>P</span>2<span>O</span>5)=21г.
Найти:
<span>W</span>2 (<span>H</span>3<span>PO</span>4)
Решение:
<span><span>1)</span></span><span>m2=m1+m2=180+21=201</span>г.
<span><span>2)</span></span><span>m1=180*0.12=21.6</span> г.
<span><span>3)</span></span><span>m</span>2=21,6+21=42,6 г.
<span><span>4)</span></span><span>W</span>2 (<span>H</span>3<span>PO</span>4)=42,6/201=0,21=21%
Ответ: 21%