Q: A solution has a pH of 2. What is the $$[H^+]$$ concentration?

$$[H^+] = 1 \times 10$$^{-2}$$ M

Question 1

Which property of water is primarily responsible for its ability to moderate Earth's climate and maintain stable temperatures in aquatic environments?

Accepted Answer

Water's high specific heat

Question 2

A sodium chloride (NaCl) crystal is placed in water. What happens at the molecular level to allow NaCl to dissolve?

Accepted Answer

Water molecules surround each ion, forming a hydration shell through electrostatic interactions

Question 3

Which of the following best explains why ice floats on liquid water?

Accepted Answer

Ice is less dense than liquid water due to the formation of a crystalline lattice by hydrogen bonds

Question 4

A solution has a hydrogen ion concentration of $$[H^+] = 1 	imes 10$$^{-5}$$ M. What is the pH of this solution?

Accepted Answer

$$pH = 5$$

Question 5

If the pH of a solution changes from 7 to 4, how does the hydrogen ion concentration change?

Accepted Answer

It increases by 1,000 times

Question 6

Which of the following substances would be considered hydrophobic?

Accepted Answer

Vegetable oil

Question 7

Why is water considered a 'universal solvent'?

Accepted Answer

It can dissolve many polar and ionic substances due to its polarity and ability to form hydrogen bonds

Question 8

Which of the following best describes the interaction between water molecules that gives rise to its unique properties?

Accepted Answer

Hydrogen bonds between the partially positive hydrogen of one molecule and the partially negative oxygen of another

Question 9

A sports drink advertises a high pH. What does this imply about the drink's hydrogen ion concentration?

Accepted Answer

It has a low concentration of $$H^+$$ ions

Question 10

Which of the following scenarios best illustrates water's cohesive behavior?

Accepted Answer

Water molecules sticking together to form droplets on a leaf

Question 11

A solution at 25°C has $$[OH^-] = 1 	imes 10$$^{-9}$$ M. What is the pH of the solution?

Accepted Answer

$$pH = 5$$

Question 12

Which of the following statements about acids and bases is correct?

Accepted Answer

An acid increases the concentration of $$H^+ in a $$solution

Question 13

Which of the following best explains why sweating helps cool the human body?

Accepted Answer

Evaporation of water from the skin absorbs heat due to water's high heat of vaporization

Question 14

A solution has a pH of 2. What is the $$[H^+]$$ concentration?

Accepted Answer

$$[H^+] = 1 	imes 10$$^{-2}$$ M

Question 15

Which of the following is a real-world consequence of water's expansion upon freezing?

Accepted Answer

Ice floats, insulating the water below and allowing aquatic life to survive winter

Question 16

Which of the following best describes a hydration shell?

Accepted Answer

A layer of water molecules surrounding a dissolved ion

Question 17

If a solution has $$[H^+] = 1 	imes 10$$^{-8}$$ M, what is its pOH?

Accepted Answer

$$pOH = 6$$

Question 18

Which of the following is NOT an emergent property of water that contributes to Earth's suitability for life?

Accepted Answer

High density as a solid

Question 19

Which of the following best explains why water can dissolve table salt (NaCl) but not oil?

Accepted Answer

Water is polar and dissolves polar and ionic substances, but oil is nonpolar

Question 20

A patient is found to have blood with a pH of 7.1. Compared to normal blood (pH 7.4), how much more acidic is the patient's blood?

Accepted Answer

About 2 times more acidic (since each 0.3 pH unit is about 2 times change in $$[H^+])$$

Water and the Chemistry of Life: Properties, Solutions, and Biological Molecules

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