Question

a solid reactant is placed into a beaker of a warm water. the liquid vigorously bubbles as the solid dissolves into the solution. what will most likely happen if the temperature of the liquid is slightly reduced?
more bubbles will be produced because the solution is becoming more concentrated.
fewer bubbles will be produced because of fewer collisions of reactant molecules.
the solid will get smaller at a faster rate because of more collisions of reactant molecules.
the solid will get larger at a slower rate because precipitate is coming out of the solution

Explanation:

The reaction here involves a solid dissolving and producing bubbles (a chemical reaction, likely due to gas production). Reaction rate is related to molecular collisions. Temperature affects the kinetic energy of molecules: lower temperature means lower kinetic energy, so fewer collisions between reactant molecules. Fewer collisions lead to a slower reaction rate, so fewer bubbles. Let's analyze each option:

• Option 1: Reducing temperature doesn't make the solution more concentrated in a way that increases bubbling; in fact, reaction rate should decrease. Eliminate.
• Option 2: Lower temperature → lower molecular kinetic energy → fewer collisions → slower reaction → fewer bubbles. This matches.
• Option 3: Lower temperature means fewer collisions, so the solid should dissolve slower, not faster. Eliminate.
• Option 4: The reaction is dissolution (solid dissolving) with gas production, not precipitation (which would make solid larger, but lower temp slows reaction, and the process here is dissolving, not precipitating in reverse in a way described). Eliminate.

Answer:

B. Fewer bubbles will be produced because of fewer collisions of reactant molecules.