A 10 mg effervescent tablet containing sodium bicarbonate and oxalic acid releases 0.25 ml of CO₂ at T = 298.15 K and p = 1 bar. If molar volume of CO₂ is 25.0 L under such condition, what is the percentage of sodium bicarbonate in each tablet ? [Molar mass of NaHCO₃ = 84g mol^–1]

$2{\mathrm{NaHCO}}_3+{\mathrm{H}}_2{\mathrm{C}}_2{\mathrm{O}}_4\to {\mathrm{Na}}_2{\mathrm{C}}_2{\mathrm{O}}_4+2{\mathrm{CO}}_2+2{\mathrm{H}}_2\mathrm{O}$

Here, number of moles of CO₂​= $\frac{0.25\times {10}^{-3}}{25.9}\approx {10}^{-5}$

Now, one mole of CO_2​ is produced by one mole of NaHCO₃​.

The number of moles of NaHCO_3​ in the given reaction= number of moles of CO₂​=10⁻⁵

Now, the weight of NaHCO₃​=10⁻⁵×84=84×10⁻⁵g

%Mass= $\frac{84\times {10}^{-5}}{10\times {10}^{-3}}\times 100=8.4\%$