Q: A scientist wants to prepare 500 mL of a 5 M NaCl solution. Given the molecular mass of NaCl is 58.44 g/mol, how many grams of NaCl are required?

$$58.44 \times 5 \times 0.5 = 146.1 g$$

Q: What is the pH of a solution with a hydrogen ion concentration of $$[H^+] = 1 \times 10$$^{-4}$$ mol/L?

$$pH = -\log(1 \times 10$$^{-4}$$) = 4$$

Q: A solution is made by dissolving 90.1 g of glucose ($$C_6H_{12}O_6$, molecular mass = 180.2 g/mol) in enough water to make 500 mL. What is the molarity of the solution?

$$M = \frac{90.1}{180.2 \times 0.5} = 1 M$$

Question 1

Which property of water is primarily responsible for the ability of trees to transport water from their roots to their leaves against gravity?

Accepted Answer

Cohesion

Question 2

Why does ice float on liquid water?

Accepted Answer

Hydrogen bonds in ice are more ordered, creating a less dense structure

Question 3

A scientist wants to prepare 500 mL of a 5 M NaCl solution. Given the molecular mass of NaCl is 58.44 g/mol, how many grams of NaCl are required?

Accepted Answer

$$58.44 	imes 5 	imes 0.5 = 146.1 g$$

Question 4

Which of the following best explains why water has a high specific heat?

Accepted Answer

Hydrogen bonds between water molecules require significant energy to break

Question 5

What is the pH of a solution with a hydrogen ion concentration of $$[H^+] = 1 	imes 10$$^{-4}$$ mol/L?

Accepted Answer

$$pH = -\log(1 	imes 10$$^{-4}$$) = 4$$

Question 6

Which of the following substances is hydrophobic?

Accepted Answer

Oil

Question 7

A buffer in human blood helps maintain pH by which mechanism?

Accepted Answer

Reversibly binding or releasing $$H^+$$ ions

Question 8

Which equation correctly represents the relationship between hydrogen ion and hydroxide ion concentrations in pure water at 25°C?

Accepted Answer

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

Question 9

Which property of water allows insects, such as water striders, to walk on the surface of ponds?

Accepted Answer

Surface tension

Question 10

A solution is made by dissolving 90.1 g of glucose ($$C_6H_{12}O_6$, molecular mass = 180.2 g/mol) in enough water to make 500 mL. What is the molarity of the solution?

Accepted Answer

$$M = \frac{90.1}{180.2 	imes 0.5} = 1 M$$

Question 11

Which of the following best describes why water is a versatile solvent?

Accepted Answer

Water's polarity allows it to form hydrogen bonds with many substances

Question 12

If the pH of a solution changes from 7 to 5, how does the hydrogen ion concentration change?

Accepted Answer

It increases by 100 times

Question 13

Which of the following is an example of evaporative cooling in living organisms?

Accepted Answer

Sweating during exercise

Question 14

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

Accepted Answer

Acids increase the concentration of $$H^+ in $$solution

Question 15

Which of the following is a consequence of ocean acidification caused by increased $$CO_2$$ absorption?

Accepted Answer

Decrease in calcification by marine organisms

Question 16

Which of the following best describes a hydrophilic substance?

Accepted Answer

A substance that has an affinity for water due to its polarity

Question 17

What is the molecular mass of NaCl, given the atomic masses Na = 22.99 and Cl = 35.45?

Accepted Answer

$$22.99 + 35.45 = 58.44 g/$$mol

Question 18

Which of the following is NOT a property of water that facilitates an environment for life?

Accepted Answer

Low specific heat

Question 19

Why is the high specific heat of water important for coastal climates?

Accepted Answer

It minimizes temperature fluctuations, creating a stable environment

Water and Life (Chapter 3): Properties, Functions, and Biological Importance

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