Question

A 3-column table with 5 rows titled acidity changes after dry ice is added. the first column is labeled time (seconds) with entries 0, 1, 2, 3, 4. the second column is labeled ph of solution a with entries 11.0, 10.8, 10.2, 9.6, 9.0. the third column is labeled ph of solution b with entries 8.5, 8.0, 7.2, 6.5, 5.8. what happens to the acidity of solutions a and b after dry ice is added? the ph of solution a decreases, and the ph of solution b increases. the ph of solution a increases, and the ph of solution b decreases. the ph of solution a increases, and the ph of solution b increases. the ph of solution a decreases, and the ph of solution b decreases.

Answer 1

Upon the addition of dry ice to solutions A and B, the pH levels decrease for both solutions, indicating an increase in acidity. This happens because the carbon dioxide from dry ice forms carbonic acid when dissolved in water, increasing the concentration of hydronium ions [H3O+]. Therefore, both solution A and B become more acidic.

Step-by-step explanation:

When dry ice, which is solid carbon dioxide (CO2), is added to solutions A and B, it sublimates to gaseous CO2 and dissolves in the water, forming carbonic acid (H2CO3). This causes the concentration of hydronium ions [H3O+] in the solution to increase.

Because the pH scale is a reciprocal measure of [H3O+] concentration, an increase in acidity results in a decrease in pH. As observed in the data, the pH for both solutions A and B decreases over time after the addition of dry ice, confirming that the acidity of both solutions increases.

The pH of solution A decreases from 11.0 to 9.0, and the pH of solution B decreases from 8.5 to 5.8 over a time course of 4 seconds. The reduction in pH values indicates a shift towards increased acidity. This is expected because adding CO2 to water forms carbonic acid and subsequently increases the [H3O+] concentration.

This clearer understanding of pH levels helps in concluding that the pH of solution A decreases, and the pH of solution B decreases, meaning both become more acidic.