Stoichiometric relationships in solution rely on the conservation of atoms and the…
CHEMISTRY · Multi-part · A Level · Chemistry · Amount of substance · Amount of substance
Problem
Stoichiometric relationships in solution rely on the conservation of atoms and the proportionality reflected by coefficients in a balanced chemical equation. Consider the reaction that occurs when aqueous silver nitrate is mixed with aqueous barium chloride:
2AgNO3(aq)+BaCl2(aq)→2AgCl(s)+Ba(NO3)2(aq)
Two students each mix 50.0 mL of 0.100 M AgNO3 with 50.0 mL of 0.100 M BaCl2. One student accidentally doubles the volume of the AgNO3 solution while keeping all other conditions the same.
(a) Describe what is meant by conservation of atoms in the context of aqueous reactions such as the one above.
(b) Explain how the coefficients in the balanced equation dictate the mole relationship between Ag+ and Cl− ions when equal volumes of the two 0.100 M solutions are mixed.
(c) For the student who doubled the volume of the AgNO3 solution, discuss qualitatively how the molarity of Ag+ ions changes and whether the total number of Ag+ ions present before mixing has changed. Relate your discussion to the conservation principle described in part (a).