Ta có: \(n_{Ca\left(OH\right)_2}=0,2.1=0,2\left(mol\right)\)
PT: \(Ca\left(OH\right)_2+Na_2CO_3\rightarrow CaCO_{3\downarrow}+2NaOH\)
_______0,2_______0,2________0,2 (mol)
\(\Rightarrow C_{M_{Na_2CO_3}}=\dfrac{0,2}{0,25}=0,8\left(M\right)\)
\(m_{CaCO_3}=0,2.100=20\left(g\right)\)