Final answer:
To determine the molar mass of a metal carbonate, the carbonate reacts with excess hydrochloric acid producing a metal chloride, carbon dioxide, and water. The remaining excess HCl is titrated with NaOH. The reactions are MCO₃(s) + 2HCl(aq) → MCl₂(aq) + CO₂(g) + H₂O(l), followed by HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l).
Step-by-step explanation:
The reactions involved in obtaining the molar mass of a metal carbonate (MCO₃) using hydrochloric acid (HCl) and back-titrating the excess acid with sodium hydroxide (NaOH) include:
- Reaction with HCl: MCO₃(s) + 2HCl(aq) → MCl₂(aq) + CO₂(g) + H₂O(l)
- Back titration: HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l)
This process begins with the metal carbonate reacting with hydrochloric acid to produce a metal chloride, carbon dioxide, and water. Any excess hydrochloric acid is then titrated with sodium hydroxide to determine how much acid was used in the reaction with the metal carbonate. The calculations can then be performed to find the molar mass of the metal carbonate based on the amount of hydrochloric acid that reacted.