Em tham khảo nha:
\(\begin{array}{l}
PbS{O_4}:\\
{M_{PbS{O_4}}} = 207 + 32 + 16 \times 4 = 303g/mol\\
\% {m_{Pb}} = \dfrac{{207}}{{303}} \times 100\% = 68,32\% \\
\% {m_S} = \dfrac{{32}}{{303}} \times 100\% = 10,56\% \\
\% {m_O} = 100 - 68,32 - 10,56 = 21,12\% \\
A{l_2}{(S{O_4})_3}.2Si{O_2}\\
{M_{A{l_2}{{(S{O_4})}_3}.2Si{O_2}}} = 27 \times 2 + 32 \times 3 + 16 \times 12 + 2 \times 28 + 2 \times 16 \times 2 = 462\,g/mol\\
\% {m_{Al}} = \dfrac{{27 \times 2}}{{462}} \times 100\% = 11,69\% \\
\% {m_S} = \dfrac{{32 \times 3}}{{462}} \times 100\% = 20,78\% \\
\% {m_{Si}} = \dfrac{{28 \times 2}}{{462}} \times 100\% = 12,12\% \\
\% {m_O} = 100 - 11,69 - 20,78 - 12,12 = 55,41\%
\end{array}\)
