Question

Formic acid, HCHO2, burns in oxygen to form carbon dioxide and water as follows: HCHO2 (aq) + O2 (g) → 2 CO2 (g) + 2 H2O (l). If a 3.15-g sample of formic acid was burned in 2.0 L of oxygen, what volume of carbon dioxide would be produced? (Assume the reaction occurs at standard temperature and pressure, STP.

Answer 1

$n(HCHO_2)=\dfrac{Mass}{Molar\ mass}=\dfrac{3.15\ g}{46\ g/mol}=0.06848\ mol$

At STP, one mole of gas occupies 22.4 L of volume (molar volume).

$n(O_2)=\dfrac{Volume}{Molar\ volume}=\dfrac{2.0\ L}{22.4\ L/mol}=0.08929\ mol$

Balanced equation: 2HCHO_{2 (aq)} + O_{2 (g)} → 2CO_{2 (g)} + 2H₂O _(l)

Formic acid is the limiting reactant.

$n(CO_2)=n(HCHO_2)=0.06848\ mol$

$V(CO_2)=Amount*Molar\ volume=0.06848\ mol\ *\ 22.4\ L/mol =1.534\ L$