Which type of bond must be broken for water to vaporize?
A) ionic bonds
B) nonpolar covalent bonds
C) polar covalent bonds
D) hydrogen bonds
E) covalent bonds
Temperature usually increases when water condenses. Which behavior of water is most directly responsible for this phenomenon?
A) the change in density when it condenses to form a liquid or solid
B) reactions with other atmospheric compounds
C) the release of heat by the formation of hydrogen bonds
D) the release of heat by the breaking of hydrogen bonds
E) the high surface tension of water
At what temperature is water at its densest?
Why does ice float in liquid water?
A) The liquid water molecules have more kinetic energy and thus support the ice.
B) The ionic bonds between the molecules in ice prevent the ice from sinking.
C) Ice always has air bubbles that keep it afloat.
D) Hydrogen bonds stabilize and keep the molecules of ice farther apart than the water molecules of liquid water.
E) The crystalline lattice of ice causes it to be denser than liquid water.
Based on your knowledge of the polarity of water molecules, the solute molecule is most likely
A) positively charged.
B) negatively charged.
C) without charge.
Hydrophobic substances such as vegetable oil are
A) nonpolar substances that repel water molecules.
B) nonpolar substances that have an attraction for water molecules.
C) polar substances that repel water molecules.
D) polar substances that have an affinity for water.
E) charged molecules that hydrogen-bond with water molecules.
One mole (mol) of a substance is
A) 6.02 × 10^23 molecules of the substance.
B) 1 g of the substance dissolved in 1 L of solution.
C) the largest amount of the substance that can be dissolved in 1 L of solution.
D) the molecular mass of the substance expressed in grams.
E) A and D only
How many molecules of glucose (C6H2O6 molecular mass =180 daltons) would be present in one mole of glucose?
C) 3 × 10^14
D) 180 × 10^14
E) 6.02 × 10^23
How many molecules of glycerol (C3H8O3) would be present in 1 L of a 1 M glycerol solution?
D) 1 × 10^7
E) 6.02 × 10^23
When an ionic compound such as sodium chloride (NaCl) is placed in water the component atoms of the NaCl crystal dissociate into individual sodium ions (Na+) and chloride ions (Cl-). In contrast, the atoms of covalently bonded molecules (e.g., glucose, sucrose, glycerol) do not generally dissociate when placed in aqueous solution. Which of the following solutions would be expected to contain the greatest number of particles (molecules or ions)?
A) 1 L of 0.5 M NaCl
B) 1 L of 0.5 M glucose
C) 1 L of 1.0 M NaCl
D) 1 L of 1.0 M glucose
E) C and D will contain equal numbers of particles.