3. Water

In a neutral solution, the concentration of __________.

a) Hydrogen ions is less than the concentration of hydroxide ions.

b) Water molecules is less than the concentration of hydroxide ions.

c) Hydrogen ions is greater than the concentration of hydroxide ions.

d) Hydrogen ions is equal to the concentration of hydroxide ions.

A base _______:

a) Has a value of 7 on the pH scale.

b) Is a chemical that donates hydrogen ions to a solution.

c) Is a chemical that accepts hydrogen ions from a solution.

d) Has a value below 7 on the pH scale.

e) None of the above are correct.

Which of the following statements about buffers is true?

a) They maintain a consistent pH only when acids are added to them, but not bases.

b) They maintain a consistent pH of 7.

c) They fluctuate in pH when acids are added to them.

d) They maintain a consistent pH when acids or bases are added to them.

e) They fluctuate in pH when acids or bases are added to them.

Measurements show that the pH of a particular lake is 4.0. What is the hydrogen ion concentration of the lake? a. 4.0 M b. 10−10 M c. 10−4 M d. 104 M

What is the hydroxide ion concentration of the lake described in question 3? a. 10−10 M b. 10−4 M c. 10−7 M d. 10.0 M

If you were given a solution that has a pH of 8.5, what would be its concentration of protons? What is the difference in proton concentration between this solution and one that has a pH of 7?

Consider the reaction between carbon dioxide and water to form carbonic acid (CH2O3):

CO2(𝑔)+H2O(𝑙)⇌CH2O3(𝑎𝑞)

In the ocean, carbonic acid immediately dissociates to form a proton and bicarbonate ion, as follows:

CH2O3(𝑎𝑞)⇌CHO3−(𝑎𝑞)+H+(𝑎𝑞)

As atmospheric CO2 increases, the ocean absorbs more of the gas. Would this sequence of reactions be driven to the left or the right? How would this affect the pH of the ocean?

Stony corals secrete thin layers of calcium carbonate (CaCO3) to build the foundation of coral reefs. The relationship between calcium carbonate, carbonic acid, and calcium bicarbonate (Ca(HCO3)2) is shown below:

CH2O3(𝑎𝑞)+CaCO3(𝑠) ⇌ Ca(HCO3)2(𝑎𝑞)

Predict what will happen to the calcium carbonate foundation of reefs as CO2 levels rise in the oceans.

The current average pH of our oceans is 8.1. What is the concentration of protons in the oceans? How has the proton concentration changed in our oceans when compared to before the industrial revolution, when the average pH was 8.2? Express this change as a percentage increase.