$\begin{cases}n_{CO_2}=0,12 mol \\ m_{MOH}=7,2 gam \end{cases}$$MOH+CO_2\rightarrow MHCO_3$ $x x x$$2MOH+CO_2\rightarrow M_2CO_3+H_2O$ $2y y y$$*)P_1:$$M_2CO_3+BaCl_2\rightarrow BaCO_3\downarrow+2MCl$ $0,5y 0,5y$$*)P_2$$MHCO_3+Ba(OH)_2\rightarrow BaCO_3\downarrow+MOH+H_2O$ $0,5x 0,5x$$M_2CO_3+Ba(OH)_2\rightarrow BaCO_3\downarrow+2MOH$ $0,5y 0,5y$$\Rightarrow \begin{cases}x+y=0,12\\0,5y=\frac{5,91}{197} \\ 0,5(x+y)>\frac{5,91}{197} \end{cases}\Rightarrow \begin{cases}x=0,06 \\ y=0,06 \end{cases}\Rightarrow n_{MOH}=x+2y=0,18 mol$$\Rightarrow \frac{7,2}{M+17}=0,18\Rightarrow M=23\Rightarrow M:Na$$\Rightarrow m=197.0,5(x+y)=197.0,06=11,82 gam$
$\begin{cases}n_{CO_2}=0,12 mol \\ m_{MOH}=7,2 gam \end{cases}$$MOH+CO_2\rightarrow MHCO_3$ $x x x$$2MOH+CO_2\rightarrow M_2CO_3+H_2O$ $2y y y$$*)P_1:$$M_2CO_3+BaCl_2\rightarrow BaCO_3\downarrow+2MCl$ $0,5y 0,5y$$*)P_2$$MHCO_3+Ba(OH)_2\rightarrow BaCO_3\downarrow+MOH+H_2O$ $0,5x 0,5x$$M_2CO_3+Ba(OH)_2\rightarrow BaCO_3\downarrow+2MOH$ $0,5y 0,5y$$\Rightarrow \begin{cases}x+y=0,12\\0,5y=\frac{5,91}{197} \\ 0,5(x+y)>\frac{5,91}{197} \end{cases}\Rightarrow \begin{cases}x=0,06 \\ y=0,06 \end{cases}\Rightarrow n_{MOH}=x+2y=0,18 mol$$\Rightarrow \frac{7,2}{M+17}=0,18\Rightarrow M=23\Rightarrow M:Na$$\Rightarrow m=197(x+y)=197.0,12=23,64 gam$
$\begin{cases}n_{CO_2}=0,12 mol \\ m_{MOH}=7,2 gam \end{cases}$$MOH+CO_2\rightarrow MHCO_3$ $x x x$$2MOH+CO_2\rightarrow M_2CO_3+H_2O$ $2y y y$$*)P_1:$$M_2CO_3+BaCl_2\rightarrow BaCO_3\downarrow+2MCl$ $0,5y 0,5y$$*)P_2$$MHCO_3+Ba(OH)_2\rightarrow BaCO_3\downarrow+MOH+H_2O$ $0,5x 0,5x$$M_2CO_3+Ba(OH)_2\rightarrow BaCO_3\downarrow+2MOH$ $0,5y 0,5y$$\Rightarrow \begin{cases}x+y=0,12\\0,5y=\frac{5,91}{197} \\ 0,5(x+y)>\frac{5,91}{197} \end{cases}\Rightarrow \begin{cases}x=0,06 \\ y=0,06 \end{cases}\Rightarrow n_{MOH}=x+2y=0,18 mol$$\Rightarrow \frac{7,2}{M+17}=0,18\Rightarrow M=23\Rightarrow M:Na$$\Rightarrow m=197
.0,5(x+y)=197.0,
06=
11,
82 gam$