A solid pellet of Na2CO3(s) with a mass of 0.50 g is dropped into 20.0 mL of 1.00 M…
CHEMISTRY · Multi-part · AP · Chemistry · Chemical Reactions · Chemical Reactions
Problem
A solid pellet of Na2CO3(s) with a mass of 0.50 g is dropped into 20.0 mL of 1.00 M HCl(aq) in an open beaker at 298 K. The reaction proceeds until either all of one reactant is consumed or the HCl evaporates (assume no HCl is lost to evaporation). The balanced chemical equation is
2 HCl(aq) + Na2CO3(s) → 2 NaCl(aq) + H2O(l) + CO2(g)
Water molecules in the solvent need not be shown explicitly unless requested.
(a) Calculate the number of moles of each reactant initially present and identify the limiting reactant.
(b) Determine the theoretical number of moles of CO2(g) that should be produced when the reaction goes to completion under the stated conditions.
(c) Sketch a particulate-level representation of the system immediately BEFORE the reaction begins. Depict the solid Na2CO3 lattice (as a cluster of ions), solvated H3O^+ ions (to represent the proton donor in HCl), and solvated Cl^− ions. Use a scale corresponding to one full stoichiometric cycle based on the limiting reactant.
(d) Sketch a particulate-level representation of the system AFTER the reaction has gone to completion. Show all species present, clearly distinguishing the aqueous phase, the liquid water molecules that form, and the CO2 molecules that have escaped into the gas phase above the solution. Reflect the quantities predicted in part (b) and any excess reagent remaining.
(e) Explain how the before-and-after sketches demonstrate mass conservation, charge balance, and the connection between macroscopic amounts (grams, moles) and particulate counts.