3. Water

Which of the following reactions is most consistent with that of a base?

a) NH₄⁺ → NH₃ + H⁺

b) H₂CO₃ → HCO₃^- + H⁺

c) NaOH → Na⁺ + OH^-

d) HCl → H⁺ + Cl^-

The addition of an acid like HCl to an aqueous solution (pure water) would result in:

a) An increase in pH only.

b) Both the release of H⁺ and an increase in pH.

c) Both the release of H⁺ and a decrease in pH.

d) The release of H⁺ into the solution only.

e) A decrease in pH only.

In what way(s) do bases work to increase the pH of a solution?

a) Increasing the concentration of hydroxide ions.

b) Decreasing the concentration of hydrogen ions.

c) Decreasing the concentration of hydroxide ions.

d) Increasing the concentration of hydrogen ions.

e) Both a & b.

f) Both c & d.

Consider the reaction between carbon dioxide and water to form carbonic acid: CO2(g)+H2O(l)⇌CH2O3(aq) In the ocean, carbonic acid immediately dissociates to form a proton and bicarbonate ion, as follows: CH2O3(aq)+H+(aq)⇌CHO3−(aq) If an underwater volcano bubbled additional CO2 into the ocean, would this sequence of reactions be driven to the left or the right? How would this affect the pH of the ocean?

When H2 and CO2 react, acetic acid can be formed spontaneously while the production of formaldehyde requires an input of energy. Which of these conclusions can be drawn from this observation? a. More heat is released when formaldehyde is produced compared to the production of acetic acid. b.Compared to the reactants that it is formed from, formaldehyde has more potential energy than does acetic acid. c. Entropy decreases when acetic acid is produced and increases when formaldehyde is produced. d. Only acetic acid could be produced under conditions that existed in early Earth.

Data from the preceding experiment were collected at different times throughout each day over a period of one year under both present-day and estimated year 2100 conditions. Averages from these samples are provided in the following graph

Using the equation in Question 13, what do the positive and negative values indicate in terms of the directionality of this reaction? What implications do these data have on reef stability in the year 2100 if there is no intervention?