Em tham khảo nha:
\(\begin{array}{l}
3)\\
a)\\
{M_A} = 2,5 \times 32 = 80\,g/mol\\
b)\\
{n_A} = \dfrac{V}{{22,4}} = \dfrac{{6,72}}{{22,4}} = 0,3\,mol\\
{M_A} = n \times M = 0,3 \times 80 = 24g\\
c)\\
{m_S} = 80 \times 40\% = 32g\\
{m_O} = 80 - 32 = 48g\\
{n_S} = \dfrac{{32}}{{32}} = 1\,mol\\
{n_O} = \dfrac{{48}}{{16}} = 3\,mol\\
{n_S}:{n_O} = 1:3 \Rightarrow CTHH:S{O_3}\\
4)\\
a)\\
2Mg + {O_2} \xrightarrow{t^0} 2MgO\\
b)\\
{n_{Mg}} = \dfrac{m}{M} = \dfrac{{480}}{{24}} = 20\,mol\\
{n_{MgO}} = {n_{Mg}} = 20\,mol\\
{m_{MgO}} = n \times M = 20 \times 40 = 800g\\
c)\\
{n_{{O_2}}} = \dfrac{{20}}{2} = 10\,mol\\
{V_{kk}} = 10 \times 22,4 \times 5 = 1120l
\end{array}\)
