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# 限量试剂和产率

## 例题 1：找出限量试剂

$2\text{Al}\left(s\right)+3{\text{Cl}}_{2}\left(g\right)\to 2{\text{AlCl}}_{3}\left(s\right)$

### 第二步：使用化学计量比找到限量试剂。

$\text{实际比率}=\frac{\text{Al的摩尔数}}{{\text{Cl}}_{2}\mathrm{的}\mathrm{摩}\mathrm{尔}\mathrm{数}}=\frac{1.04×{10}^{-1}\phantom{\rule{0.167em}{0ex}}\text{mol Al}}{5.99×{10}^{-2}\phantom{\rule{0.167em}{0ex}}{\text{mol Cl}}_{2}}=\frac{1.74\phantom{\rule{0.167em}{0ex}}\text{mol Al}}{{\text{1 mol Cl}}_{2}}$

$\text{化学计量比}=\frac{2\phantom{\rule{0.167em}{0ex}}\text{mol Al}}{3\phantom{\rule{0.167em}{0ex}}{\text{mol Cl}}_{2}}=\frac{0.67\phantom{\rule{0.167em}{0ex}}\text{mol Al}}{1\phantom{\rule{0.167em}{0ex}}{\text{mol Cl}}_{2}}$

${\text{Cl}}_{2}\mathrm{的}\mathrm{摩}\mathrm{尔}\mathrm{数}=1.04×{10}^{-1}\phantom{\rule{0.167em}{0ex}}\overline{)\text{mol Al}}×\frac{3\phantom{\rule{0.167em}{0ex}}{\text{mol Cl}}_{2}}{2\phantom{\rule{0.167em}{0ex}}\overline{)\text{mol Al}}}=1.56×{10}^{-1}\phantom{\rule{0.167em}{0ex}}{\text{mol Cl}}_{2}$

$1\phantom{\rule{0.167em}{0ex}}\text{mol-rxn}=2\phantom{\rule{0.167em}{0ex}}\text{mol Al}=3\phantom{\rule{0.167em}{0ex}}{\text{mol Cl}}_{2}=2\phantom{\rule{0.167em}{0ex}}{\text{mol AlCl}}_{3}$

## 例题 2：计算理论产量

$\text{理论产量的摩尔数}=5.99×{10}^{-2}\phantom{\rule{0.167em}{0ex}}\overline{){\text{mol Cl}}_{2}}×\frac{2\phantom{\rule{0.167em}{0ex}}{\text{mol AlCl}}_{3}}{3\phantom{\rule{0.167em}{0ex}}\overline{){\text{mol Cl}}_{2}}}=3.99×{10}^{-2}\phantom{\rule{0.167em}{0ex}}{\text{mol AlCl}}_{3}$

$\text{理论产量的克数}=3.99×{10}^{-2}\phantom{\rule{0.167em}{0ex}}\overline{){\text{mol AlCl}}_{3}}×\frac{133.33\phantom{\rule{0.167em}{0ex}}{\text{g AlCl}}_{3}}{1\phantom{\rule{0.167em}{0ex}}\overline{){\text{mol AlCl}}_{3}}}=5.32\phantom{\rule{0.167em}{0ex}}{\text{g AlCl}}_{3}$

## 产率

$\text{产率}=\frac{\text{实际产量}}{\text{理论产量}}×100\mathrm{%}$

## 例题 3：计算理论产量和产率

${\text{BaCl}}_{2}\left(aq\right)+2{\text{AgNO}}_{3}\left(aq\right)\to 2\text{AgCl}\left(s\right)+{\text{Ba(NO}}_{3}{\right)}_{2}\left(aq\right)$

### 第一步：找出限量试剂的摩尔数。

$1.56\phantom{\rule{0.167em}{0ex}}\overline{){\text{g BaCl}}_{2}}×\frac{1\phantom{\rule{0.167em}{0ex}}{\text{mol BaCl}}_{2}}{208.23\phantom{\rule{0.167em}{0ex}}\overline{){\text{g BaCl}}_{2}}}=7.49×{10}^{-3}\phantom{\rule{0.167em}{0ex}}{\text{mol BaCl}}_{2}$

### 第二步：计算产品的摩尔数。

$7.49×{10}^{-3}\phantom{\rule{0.167em}{0ex}}\overline{){\text{mol BaCl}}_{2}}×\frac{2\phantom{\rule{0.167em}{0ex}}\text{mol AgCl}}{1\phantom{\rule{0.167em}{0ex}}\overline{){\text{mol BaCl}}_{2}}}=1.50×{10}^{-2}\text{mol AgCl}$

### 第三步：把产品的摩尔数转换成克。

$1.50×{10}^{-2}\phantom{\rule{0.167em}{0ex}}\overline{)\text{mol AgCl}}×\frac{143.32\phantom{\rule{0.167em}{0ex}}\text{g AgCl}}{1\phantom{\rule{0.167em}{0ex}}\overline{)\text{mol AgCl}}}=2.15\phantom{\rule{0.167em}{0ex}}\text{g AgCl}$

$\begin{array}{rl}\text{产率}& =\frac{\text{实际产量}}{\text{理论产量}}×100\mathrm{%}\\ \\ & =\frac{1.82\phantom{\rule{0.167em}{0ex}}\text{g AgCl}}{2.15\phantom{\rule{0.167em}{0ex}}\text{g AgCl}}×100\mathrm{%}\\ \\ & =84.6\mathrm{%}\phantom{\rule{0.167em}{0ex}}\text{yield}\end{array}$