An engineer requires $3.50 \, \text{moles}$ of pure Aluminum ($Al$) for a thermite welding reaction on a railway track. Calculate the mass of Aluminum required in grams. (Atomic mass of $Al = 26.98 \, \text{g/mol}$).

Calculate the molar mass of Portland cement's main active component, Tricalcium Silicate ($Ca_3SiO_5$), and determine the number of moles in a $50.0 \, \text{kg}$ bag of pure $Ca_3SiO_5$. (Atomic masses: $Ca = 40.08$, $Si = 28.09$, $O = 16.00 \, \text{g/mol}$).

A civil engineer is analyzing the emissions of heavy construction machinery. Balance the complete combustion equation of octane ($C_8H_{18}$), the primary component of gasoline, reacting with oxygen ($O_2$) to produce carbon dioxide ($CO_2$) and water ($H_2O$).

The thermite reaction is used to weld train tracks: $Fe_2O_3 + 2Al \rightarrow 2Fe + Al_2O_3$. If $500 \, \text{g}$ of Iron(III) oxide ($Fe_2O_3$) reacts completely with excess Aluminum, calculate the mass of molten Iron ($Fe$) produced. (Molar masses: $Fe_2O_3 = 159.69 \, \text{g/mol}$, $Fe = 55.85 \, \text{g/mol}$).

An environmental engineer analyzes a volatile organic compound (VOC) found in a contaminated soil sample. The compound is found to be $85.6\%$ Carbon and $14.4\%$ Hydrogen by mass. Determine its empirical formula.

During the production of a specialized concrete admixture, chemical A and chemical B react in a 1:1 molar ratio. If $100 \, \text{kg}$ of A (Molar mass $50 \, \text{g/mol}$) is mixed with $100 \, \text{kg}$ of B (Molar mass $200 \, \text{g/mol}$), which is the limiting reactant and why does it matter?