Two colorless aqueous solutions—0.10 M lead(II) nitrate and 0.20 M potassium…
CHEMISTRY · Multi-part · AP · Chemistry · Chemical Reactions · Chemical Reactions
Problem
Two colorless aqueous solutions—0.10 M lead(II) nitrate and 0.20 M potassium iodide—are available in separate dropper bottles. A student plans to add several drops of one solution to the other in a clean, dry test tube that will then be stoppered, creating a closed system.
(1) Predict the primary macroscopic observation that will occur immediately after the two solutions are combined. Be as specific as possible about what the student will see.
(2) Explain why the initial colorless appearance of both reactant solutions imposes an experimental constraint when searching for evidence of chemical change, and state how the observation you predicted in part (a) overcomes that constraint.
(3) After the mixture is sealed with the stopper, predict whether the total mass of the test tube and its contents will increase, decrease, or remain constant over the next 24 hours, and justify your answer in terms of the closed-system condition.