H2О=4,5 г

О2=5,6л

СО2=2,8л

дано

m(CH4) = 2 g

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m(H2O)-?

V(CO2)-?

V(O2)-?

CH4+2O2--->CO2+2H2O

M(CH4) = 16 g/mol

n(CH4) = m/M= 2/16 = 0.125 mol

n(CH4) = n(CO2) = 0.125  mol

V(CO2) = n*Vm = 0.125 * 22.4 = 2.8 L

n(CH4) = 2n(O2)

n(O2) = 2*0.125 = 0.25 mol

V(O2) = n*Vm = 0.25 * 22.4 = 5.6 L

n(CH4) = 2n(H2O)

n(H2O) = 0.25 mol

M(H2O) = 18 g/mol

m(H2O) = n*M = 0.25 * 18 = 4.5 g

ответ 4.5 г , 2.8 л , 5.6 л