Question

question 10.
there are two beakers full of water. one sample is added to each beaker.
which of the following options correctly compares the rate of dissolution of the samples?
a. ○ the calcium carbonate granules will dissolve quickest since they have a larger surface area than the calcium carbonate powder.
b. ○ the calcium carbonate granules and calcium carbonate powder will dissolve at the same rate since they have the same surface area.
c. ○ the calcium carbonate powder will dissolve quicker since they have a greater surface area than the calcium carbonate granules.
d. ○ the calcium carbonate powder will dissolve slower since they have a lower surface area than the calcium carbonate granules.

Explanation:

To determine the correct option, we recall that the rate of dissolution is related to the surface area of the solute. A powder has a greater surface area than granules (since powder consists of smaller particles, exposing more surface area to the solvent). So, calcium carbonate powder will dissolve faster than calcium carbonate granules because powder has a greater surface area. Now let's analyze the options:

• Option A: Incorrect. Granules have less surface area than powder, so powder should dissolve faster, not granules. Also, the comparison of granules and powder surface area is wrong here.
• Option B: Incorrect. It states they dissolve at the same rate, but different surface areas (powder vs granules) mean different dissolution rates.
• Option C: Correct. Powder has a greater surface area than granules, so it dissolves faster.
• Option D: Incorrect. The reasoning about surface area is reversed (powder has greater, not lower, surface area than granules).

Answer:

C. The calcium carbonate powder will dissolve quicker since they have a greater surface area than the calcium carbonate granules.