The question
Name: ______________________ Date: ____________ Why some salts dissolve in acid (4 points)
Experimental setup
Two salts and some acid
A student places excess solid calcium carbonate, CaCO₃, in one beaker of water and excess solid silver bromide, AgBr, in another, and stirs until each solution is saturated. The student then adds 1.0 M HNO₃ dropwise to each beaker.
CaCO₃(s) ⇌ Ca²⁺(aq) + CO₃²⁻(aq) AgBr(s) ⇌ Ag⁺(aq) + Br⁻(aq)
The Ka of HCO₃⁻ is 4.7 × 10⁻¹¹. HBr is a strong acid.
(a) More CaCO₃ dissolves as the acid is added. Explain why, referring to Q and Ksp. [2 points]
(b) The amount of AgBr that dissolves does not change noticeably. Explain why. [1 point]
(c) A student claims the acid dissolves CaCO₃ because it increases the value of Ksp. Is the claim correct? Justify your answer. [1 point]