Mr(Mn2O7) = 55*2 + 16 *7 = 222
Mr(CaCO3) = 40 + 12 + 16 *3 = 100
W(Mn) = Ar(Mn) *n / Mr(Mn2O7) *100% = 55 * 2 / 222 *100% = 49,5%
W(O) = Ar(O) * n / Mr(Mn2O7) *100% = 16 * 7 / 222 *100% = 50,45%
W(Ca) = Ar(Ca) * n / Mr(CaCO3) *100% = 40 * 1 / 100 * 100% = 40%
W(C) = Ar(C) * n / Mr(CaCO3) * 100% = 12 *1 / 100 *100% = 12%
W(O) = Ar(O) * n / Mr(CaCO3) * 100% = 16 * 3 / 100 * 100% = 48%
Я олимпиадчик по химии в Ктл-е
углерод==85,71/12=7,1425/7,14=1
водород==14,29/1=14,29/7,14=2
СН2
CH3—NH—CH2—CH3 .<span>CH3-NH-C2H5</span>
P2O5+6NaOH=2Na3PO4+3H2O
<span>P2O5 + 6Na(+) +6OH(-) = 6Na(+) +2PO4(3-) + 3H2O</span>
<span>P2O5 + 6OH(-) = 2PO4(3-) + 3H2O</span>
Как-то так )