\(M_{NaCl}=23+35,5=58,5\) (g/mol)
\(\%m_{Na}=\dfrac{23\cdot100\%}{58,5}\approx39,3\%\)
\(\%m_{Cl}=\dfrac{35,5\cdot100\%}{58,5}\approx60,7\%\)
\(M_{NH_3}=14+1\cdot3=17\) (g/mol)
\(\%m_N=\dfrac{14\cdot100\%}{17}\approx82,4\%\)
\(\%m_H=\dfrac{3\cdot100\%}{17}\approx17,6\%\)
\(M_{Al_2O_3}=27\cdot2+16\cdot3=102\) (g/mol)
\(\%m_{Al}=\dfrac{54\cdot100\%}{102}\approx52,9\%\)
\(\%m_O=\dfrac{48\cdot100\%}{102}\approx47,1\%\)
\(M_{CaCO_3}=40+12+16\cdot3=100\) (g/mol)
\(\%m_{Ca}=\dfrac{40\cdot100\%}{100}=40\%\)
\(\%m_C=\dfrac{12\cdot100\%}{100}=12\%\)
\(\%m_O=100\%-40\%-12\%=48\%\)
\(M_{H_2SO_4}=2+32+16\cdot4=98\)(g/mol)
\(\%m_H=\dfrac{2\cdot100\%}{98}\approx2\%\)
\(\%m_S=\dfrac{32\cdot100}{98}\approx32,7\%\)
\(\%m_O=100\%-2\%-32,7\%=65,3\%\)
