\(a,S_{KNO_3\left(20^oC\right)}=\dfrac{60}{190}.100=31,6\left(g\right)\)
b, Gọi \(m_{KCl}=a\left(g\right)\)
\(\rightarrow m_{H_2O}=350-a\left(g\right)\\ \rightarrow S_{KCl\left(40^oC\right)}=\dfrac{a}{350-a}.100=40\left(g\right)\Leftrightarrow a=100\left(g\right)\)
c, Gọi \(m_{CuSO_4\left(12^oC\right)}=a\left(g\right)\)
\(\rightarrow m_{H_2O}=1335-a\left(g\right)\\ \rightarrow S_{CuSO_4\left(12^oC\right)}=\dfrac{a}{1335-a}.100=33,5\left(g\right)\\ \Leftrightarrow a=335\left(g\right)\\ \rightarrow m_{H_2O}=1335-335=1000\left(g\right)\\ \rightarrow m_{CuSO_4\left(thêm\right)}=\dfrac{1000}{100}.\left(80-33,5\right)=465\left(g\right)\)
