Introduction to Water

Individual water molecules bind to each other through:

a) Covalent bonds.

b)   Ionic bonds.

c)   Hydrogen bonds.

d)   Hydrophobic bonds.

The emergent properties of water (cohesion, high heat capacity, good solvent) come from the fact that water is ______ and ______ hydrogen bond.

a) Polar, can.

b) Polar, cannot.

c) Non-polar, can.

d) Non-polar, cannot.

Which of the following effects can occur because of the high surface tension of water?

a) Lakes cannot freeze solid in winter even with extremely low temperatures.

b) A spider can walk across the surface of a small pond.

c) Organisms can resist temperature changes, although they give off heat due to chemical reactions.

d) Sweat can evaporate from the skin, helping to keep people from overheating.

Cohesive forces in liquid water occur when:

a) The H atoms on molecules of H₂O hydrogen bond to O atoms on adjacent molecules of H₂O.

b) The H atoms on molecules of H₂O hydrogen bond to other H atoms on adjacent molecules of H₂O.

c) The atoms on molecules of H₂O hydrogen bond to other O atoms on adjacent molecules of H₂O.

d) None of the above are correct.

Solid substances are normally more dense than liquid substances. However, solid ice is LESS dense than liquid water. Why is this characteristic of solid ice important for life?

a) This characteristic allows lakes to freeze solid.

b) This characteristic allows the surface water of lakes to freeze.

c) This characteristic ensures that salt water does not freeze.

d) This characteristic is not important for life.

Which of the following is due to the high specific heat of water?

a) Oil does not mix with water.

b) A lake heats up more slowly than the surrounding environment.

c) The high surface tension of water.

d) Sugar dissolves in hot tea faster than in iced tea.

Which if the following defines the term evaporation?

a) The conversion of a liquid into a vapor.

b) The conversion of a solid into a vapor.

c) The conversion of a vapor into a liquid.

d) The conversion of a vapor into a solid.

Choose the correct statement: Liquid water ________.

a) Is less dense than ice.

b) Has a lower specific heat than most other molecules.

c) Has a higher heat of vaporization than most other molecules.

d) Is nonpolar.

A solution in which water is the solvent is called a(n) _______________ solution.

a) Polar.

b) Aqueous.

c) Hydrophobic.

d)  Complete.

The substance in a mixture that is dissolved is called the:

a) Solution.

b) Solvent.

c) Solute.

d) Aqueous solution.

What is the charge of the solute molecule in the image below based on the polarity of water?

a) Positively charged.

b) Negatively charged.

c) Uncharged.

d) Non-polar and hydrophobic.

The components of a heterogenous solution are ________________ distributed throughout.

a) Equally. 

b) Unequally.

c) Uniformly.

Hydrophobic molecules:

a) Are polar covalent molecules.

b) Easily dissolve in water.

c) Are nonpolar water “fearing” molecules. 

d) Are nonpolar water “loving” molecules.

Which of the following reactions is most consistent with that of a base?

a) NH₄⁺ → NH₃ + H⁺

b) H₂CO₃ → HCO₃^- + H⁺

c) NaOH → Na⁺ + OH^-

d) HCl → H⁺ + Cl^-

The addition of an acid like HCl to an aqueous solution (pure water) would result in:

a) An increase in pH only.

b) Both the release of H⁺ and an increase in pH.

c) Both the release of H⁺ and a decrease in pH.

d) The release of H⁺ into the solution only.

e) A decrease in pH only.

In what way(s) do bases work to increase the pH of a solution?

a) Increasing the concentration of hydroxide ions.

b) Decreasing the concentration of hydrogen ions.

c) Decreasing the concentration of hydroxide ions.

d) Increasing the concentration of hydrogen ions.

e) Both a & b.

f) Both c & d.

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.

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.

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.