3. Water

A substance that minimizes changes in the concentration of H⁺ and OH^– in a solution is a __________.

A glass of grapefruit juice, at pH 3, contains __________ H⁺ as a glass of tomato juice, at pH 4.

A solution at pH 6 contains __________ than the same amount of solution at pH 8.

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

A solution at pH 6 contains _________ H+ than the same amount of a solution at pH 8. a. 20 times more b. 100 times more c. 2 times less d. 100 times less

A can of cola consists mostly of sugar dissolved in water, with some carbon dioxide gas that makes it fizzy and makes the pH less than 7. In chemical terms, you could say that cola is an aqueous solution where water is the _________ , sugar is a _________ , and carbon dioxide makes the solution _________ . a. solvent . . . solute . . . basic b. solute . . . solvent . . . basic c. solvent . . . solute . . . acidic d. solute . . . solvent . . . acidic

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?

A recent experimental study looked at the combined effects of ocean acidification and increased ocean temperatures, both aspects of climate change, on the growth of polyps, juvenile coral animals. Researchers reported the average polyp biomass (in μg/polyp) after 42 days of growth under four treatments: a control with pH and temperature maintained close to normal reef conditions, a pH lowered by 0.2 units, a temperature raised by 1°C, and a combined lower pH and higher temperature. The results showed that polyp biomass was reduced somewhat in both the low-pH and high-temperature treatments, but the combined treatment resulted in a reduction in growth by almost a third—a statistically significant result. Experiments often look at the effects of changing one variable at a time, while keeping all other variables constant. Explain why this experiment considered two variables—both a higher temperature and a lower pH—at the same time.