Q: A solution has a hydrogen ion concentration of $$1 \times 10$$^{-5}$$ M. What is its pH?

$$pH = -\log(1 \times 10$$^{-5}$$) = 5$$

Q: A compound has a specific heat of $$0.05 \text{ cal/g}^\circ\text{C}. If $$you add 1 cal of heat to 1 g of this compound, what will be the temperature change?

$$\Delta T = \frac{1 \text{ cal}}{0.05 \text{ cal/g}^\circ\text{C}} = 20^\circ\text{C}$$

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

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

Question 1

Which property of water is primarily responsible for the ability of some insects to walk on its surface?

Accepted Answer

Cohesion due to hydrogen bonding

Question 2

A solution has a hydrogen ion concentration of $$1 	imes 10$$^{-5}$$ M. What is its pH?

Accepted Answer

$$pH = -\log(1 	imes 10$$^{-5}$$) = 5$$

Question 3

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

Accepted Answer

Hydrogen bonds in ice create a lattice that spaces molecules farther apart, lowering density

Question 4

What type of bond is formed when sodium (Na) and chlorine (Cl) combine to make NaCl?

Accepted Answer

Ionic bond

Question 5

Which of the following molecules is most likely to be hydrophobic?

Accepted Answer

Methane ($$CH_4)$$

Question 6

If you dissolve 58 grams of NaCl in enough water to make 1 liter of solution, what is the molarity of NaCl?

Accepted Answer

1.0 M

Question 7

Which statement correctly describes a polar covalent bond?

Accepted Answer

Electrons are shared unequally, resulting in partial charges

Question 8

A compound has a specific heat of $$0.05 	ext{ cal/g}^\circ	ext{C}. If $$you add 1 cal of heat to 1 g of this compound, what will be the temperature change?

Accepted Answer

$$\Delta T = \frac{1 	ext{ cal}}{0.05 	ext{ cal/g}^\circ	ext{C}} = 20^\circ	ext{C}$$

Question 9

Which of the following best describes the role of water in moderating Earth's climate?

Accepted Answer

Water's high specific heat allows it to absorb and release large amounts of heat with little temperature change

Question 10

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

Accepted Answer

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

Question 11

Which of the following is a consequence of water's ability to form hydrogen bonds?

Accepted Answer

Water exhibits cohesion and surface tension

Question 12

A solution has a pH of 3. Which of the following statements is true?

Accepted Answer

The solution is acidic and has more $$H^+$$ than $$OH^-$$

Question 13

Which of the following best describes a hydrophilic substance?

Accepted Answer

It is polar or ionic and readily interacts with water

Question 14

What is the molecular mass of NaCl? (Na = 23, Cl = 35)

Accepted Answer

58 grams/mol

Question 15

Which of the following is NOT a unique property of water due to hydrogen bonding?

Accepted Answer

Low specific heat

Question 16

If the concentration of $$OH^- in a $$solution is $$1 	imes 10$$^{-4}$$ M, what is the concentration of H$$^+$$ at 25°C?

Accepted Answer

$$[H^+] = \frac{1 	imes 10$$^{-14}$$}{1 	imes 10$$^{-4}$$} = 1 	imes 10$$^{-10}$$ M

Question 17

Which of the following best describes the difference between ionic and covalent bonds?

Accepted Answer

Ionic bonds involve transferring electrons; covalent bonds involve sharing electrons

Question 18

A student mixes NaCl in water. What happens at the molecular level?

Accepted Answer

NaCl dissociates into Na$$^+$$ and Cl$$^-$$ ions, which are surrounded by hydration shells

Question 19

Which of the following is the correct value for Avogadro's number?

Accepted Answer

$$6.02 	imes 10$$^{23}$$

Water and Life: Chemical Bonds, Properties of Water, and pH

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