\(a,PTHH:2KOH+CuSO_4\rightarrow K_2SO_4+Cu\left(OH\right)_2\\ ....0,32....0,16....0,16....0,16\left(mol\right)\\ b,n_{KOH}=\dfrac{56}{56}=1\left(mol\right)\\ m_{CuSO_4}=\dfrac{400\cdot6,4\%}{100\%}=25,6\left(g\right)\\ \Rightarrow n_{CuSO_4}=\dfrac{25,6}{160}=0,16\left(mol\right)\)
Vì \(\dfrac{n_{KOH}}{2}>\dfrac{n_{CuSO_4}}{1}\) nên tính số mol theo CuSO4
\(m_{K_2SO_4}=0,16\cdot174=27,84\left(g\right)\\ m_{Cu\left(OH\right)_2}=0,16\cdot98=15,68\left(g\right)\\ \Rightarrow m_{dd_{K_2SO_4}}=5,6+400-15,68=389,92\left(g\right)\\ \Rightarrow C\%_{K_2SO_4}=\dfrac{27,84}{389,92}\cdot100\%\approx7,14\%\)