$$[H^+][OH^-] = 1 \times 10$$^{-14}$$

Question 1

Which property of water allows ice to float on liquid water, and why is this important for aquatic life?

Accepted Answer

Water's expansion upon freezing; ice is less dense than liquid water due to stable hydrogen bonds that keep molecules farther apart.

Question 2

What type of bond forms between the oxygen atom of one water molecule and the hydrogen atom of another water molecule?

Accepted Answer

Hydrogen bond

Question 3

Why does water have a high specific heat compared to other substances?

Accepted Answer

Because hydrogen bonds between water molecules absorb and release heat slowly.

Question 4

A solution has a pH of 7. If the concentration of $$[H^+]$$ increases by a factor of 100, what is the new pH?

Accepted Answer

pH = 5

Question 5

Which of the following best explains why water is an excellent solvent for ionic and polar substances?

Accepted Answer

Water's polarity allows it to surround and separate charged and polar molecules.

Question 6

Which emergent property of water is most directly responsible for the movement of water from roots to leaves in plants?

Accepted Answer

Cohesive behavior due to hydrogen bonding

Question 7

What is the molecular mass of $$H_2O$$? (Atomic masses: H = 1, O = 16)

Accepted Answer

$$18$$ daltons

Question 8

Which of the following substances is hydrophobic?

Accepted Answer

Olive oil

Question 9

If a solution has $$[H^+] = 1 	imes 10$$^{-4}$$ M, what is its pH?

Accepted Answer

$$pH = 4$$

Question 10

Which statement best describes the polarity of a water molecule?

Accepted Answer

The oxygen atom has a partial negative charge and the hydrogen atoms have partial positive charges.

Question 11

A hydrophilic substance will most likely:

Accepted Answer

Dissolve easily in water

Question 12

Which property of water helps prevent drastic temperature changes in living organisms?

Accepted Answer

High specific heat

Question 13

What is the product of $$[H^+]$$ and $$[OH^-] in $$any aqueous solution at 25°C?

Accepted Answer

$$[H^+][OH^-] = 1 	imes 10$$^{-14}$$

Question 14

Which of the following best describes surface tension in water?

Accepted Answer

It is a measure of how difficult it is to break the surface of a liquid due to hydrogen bonding.

Question 15

A solution of pH 8 is made 1,000 times more acidic. What is the new pH?

Accepted Answer

pH = 4

Question 16

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

Accepted Answer

High reactivity with nonpolar molecules

Question 17

Which of the following best explains why aquatic organisms can survive under ice during winter?

Accepted Answer

Ice floats and insulates the water below, maintaining a liquid environment for aquatic life.

Question 18

Which of the following is true about acids and bases in aqueous solutions?

Accepted Answer

Acids increase the $$[H^+]$$ concentration, while bases decrease it.

Question 19

Which scenario best illustrates the concept of adhesion in water?

Accepted Answer

Water molecules sticking to the walls of plant vessels, helping water move upward.

Question 20

How does the structure of water contribute to its ability to dissolve salts like $$NaCl$$?

Accepted Answer

Water's polar molecules surround and separate $$Na^+$$ and $$Cl^-$$ ions through ion-dipole interactions.

Water and Life: Properties and Biological Importance (Chapter 3 Study Notes)

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