Question #5313

0.144 g of an aluminium compound X react with an excess of water to produce a gas. This gas burns completely in O2 to form H2O and 72cm3 of CO2 only. Volume of CO2 was measured at room temperature and pressure. Deduce the formula of X

Expert's answer

X - Al_{x}C_{y};

Al_{x}C_{y} + H_{2}O = Al(OH)_{3}↓ + CH_{4}↑;

CH_{4} + 2O_{2} = CO_{2} + 2H_{2}O;

ν(CH_{4}) = 0.072/22.4 = 0.0032mol;

Because the valence of Al is 3, and the valence of C is 4 and z is taken as coefficient of proportionality, then Μ(Al_{x}C_{y}) = 26*4z+12*3z;

We have the next equation: 0.0032/3 = 0.144/26*4z + 12*3z;

0.001 = 0.144/140z;

z=1.

So, formula of X is Al_{4}C_{3}.

Al

CH

ν(CH

Because the valence of Al is 3, and the valence of C is 4 and z is taken as coefficient of proportionality, then Μ(Al

We have the next equation: 0.0032/3 = 0.144/26*4z + 12*3z;

0.001 = 0.144/140z;

z=1.

So, formula of X is Al

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