\(M_{CuSO_4}=64+32+16.4=160\left(\dfrac{g}{mol}\right)\)
\(\%Cu=\dfrac{64}{160}.100\%=40\%\)
\(\%S=\dfrac{32}{160}.100\%=20\%\)
\(\%O=100\%-20\%-40\%=40\%\)
\(M_{K_2CO_3}=39.2+12+16.3=138\left(\dfrac{g}{mol}\right)\)
\(\%K=\dfrac{39.2}{138}.100\%=56,5\%\)
\(\%C=\dfrac{12}{138}.100\%=8,7\%\)
\(\%O=100\%-56,5\%-8,7\%=34,8\%\)
\(M_{Ná_2SO_4}=23.2+32+16.4=142\left(\dfrac{g}{mol}\right)\)
\(\%Na=\dfrac{23.2}{142}.100\%=32,4\%\)
\(\%S=\dfrac{32}{142}.100\%=22,5\%\)
\(\%O=100\%-32,4\%-22,5\%=45,1\%\)