3. Water

pH Scale

Multiple Choice
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.
Multiple Choice
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.
Multiple Choice
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.
Multiple Choice
A substance that minimizes changes in the concentration of H⁺ and OH^– in a solution is a __________.
Multiple Choice
A glass of grapefruit juice, at pH 3, contains __________ H⁺ as a glass of tomato juice, at pH 4.
Multiple Choice
A solution at pH 6 contains __________ than the same amount of solution at pH 8.
Open Question
Measurements show that the pH of a particular lake is 4.0. What is the hydrogen ion concentration of the lake?a. 4.0 Mb. 10−10Mc. 10−4Md. 104M
Open Question
What is the hydroxide ion concentration of the lake described in question 3?a. 10−10Mb. 10−4Mc. 10−7Md. 10.0 M
Open Question
A solution at pH 6 contains _________ H+ than the same amount of a solution at pH 8.a. 20 times moreb. 100 times morec. 2 times lessd. 100 times less
Open Question
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 . . . basicb. solute . . . solvent . . . basicc. solvent . . . solute . . . acidicd. solute . . . solvent . . . acidic
Open Question
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?
Open Question
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.