(Short Response) In an experiment, calcium carbonate reacted with different volumes of hydrochloric acid in water. One of the products formed during the experiment was carbon dioxide. The time taken for 0.89 mL of carbon dioxide to form was recorded. A partial record of the experiment is shown.

Based on your knowledge of factors that affect the rates of chemical reactions, predict the trend in the last column of the experimental record. Use complete sentences to explain the trend you predicted. You do not have to determine exact values for time; just describe the trend you would expect (increase or decrease) and why it occurs.

decrease

Explanation:

I want us to cast our minds back to the idea of concentration. Recall that concentration refers to the amount of solute in a solution.

The concentration of a solution decreases as the volume of water added to the solution increases.

Now, if we look at the table, we will notice that the mass of calcium carbonate is constant while the concentration of the hydrochloric acid in water varies. The volume of the acid is decreasing while the volume of water increases. This indicates that the acid is becoming more dilute (concentration decreases steadily).

As the concentration of acid decreases, less carbon dioxide is evolved. This is so because the rate of reaction (shown by the volume of CO2 gas evolved is dependent on the concentration of reactants. As reactant concentration decreases, the rate of reaction decreases accordingly). As such, the last column decreases steadily.