To find the mass of $\mathrm{NaHCO}_{3}$ used, subtract the mass of the crucible and cover from the mass of the crucible, cover, and $\mathrm{NaHCO}_{3}$.
\[
\text{mass of } \mathrm{NaHCO}_{3} = 51.5510 \, \text{g} - 27.5651 \, \text{g} = 23.9859 \, \text{g}
\]
Using the molar mass of $\mathrm{NaHCO}_{3}$ (84.0066 g/mol), calculate the moles of $\mathrm{NaHCO}_{3}$.
\[
\text{moles of } \mathrm{NaHCO}_{3} = \frac{23.9859 \, \text{g}}{84.0066 \, \text{g/mol}} = 0.2855 \, \text{mol}
\]
The balanced chemical equation for the decomposition of $\mathrm{NaHCO}_{3}$ is:
\[
2 \mathrm{NaHCO}_{3} \rightarrow \mathrm{Na}_{2}\mathrm{CO}_{3} + \mathrm{CO}_{2} + \mathrm{H}_{2}\mathrm{O}
\]
From the equation, 2 moles of $\mathrm{NaHCO}_{3}$ produce 1 mole of $\mathrm{Na}_{2}\mathrm{CO}_{3}$. Therefore, the moles of $\mathrm{Na}_{2}\mathrm{CO}_{3}$ produced are:
\[
\text{moles of } \mathrm{Na}_{2}\mathrm{CO}_{3} = \frac{0.2855 \, \text{mol}}{2} = 0.1428 \, \text{mol}
\]
Using the molar mass of $\mathrm{Na}_{2}\mathrm{CO}_{3}$ (105.9888 g/mol), calculate the theoretical yield:
\[
\text{theoretical yield of } \mathrm{Na}_{2}\mathrm{CO}_{3} = 0.1428 \, \text{mol} \times 105.9888 \, \text{g/mol} = 15.1347 \, \text{g}
\]
\[
\boxed{\text{Theoretical yield of } \mathrm{Na}_{2}\mathrm{CO}_{3} = 15.1347 \, \text{g}}
\]
To find the mass of the product, subtract the mass of the crucible and cover from the mass of the crucible, cover, and product.
\[
\text{mass of product} = 44.4523 \, \text{g} - 27.5651 \, \text{g} = 16.8872 \, \text{g}
\]
\[
\boxed{\text{Mass of product} = 16.8872 \, \text{g}}
\]
The percent yield is calculated using the formula:
\[
\% \text{ yield} = \left( \frac{\text{actual yield}}{\text{theoretical yield}} \right) \times 100\%
\]
Using the actual yield (mass of product) and the theoretical yield of $\mathrm{Na}_{2}\mathrm{CO}_{3}$:
\[
\% \text{ yield} = \left( \frac{16.8872 \, \text{g}}{15.1347 \, \text{g}} \right) \times 100\% = 111.58\%
\]
\[
\boxed{\% \text{ yield} = 111.58\%}
\]
\[
\boxed{\text{Theoretical yield of } \mathrm{Na}_{2}\mathrm{CO}_{3} = 15.1347 \, \text{g}}
\]
\[
\boxed{\text{Mass of product} = 16.8872 \, \text{g}}
\]
\[
\boxed{\% \text{ yield} = 111.58\%}
\]