Water Chemistry Quiz

An atom has 6 electrons in its outer shell. How many unpaired electrons does it have?

2

What is the heat of vaporization of water?

2260 J/g

How many water molecules can a single water molecule bond with?

4

You have two beakers. One contains a solution of HCl at pH = 1.0. The other contains a solution of NaOH at pH = 13. Into a third beaker, you slowly and cautiously pour 20 mL of the HCL and 20 mL of the NaOH. After complete stirring, the pH of the mixture will be a. 2.0 b. 12.0 c. 7.0 d. 5.0 e. 9.0

7.0

The average cytoplasm of the cell is what percentage of water?

80%

Which of the following effects is produced by the high surface tension of water?

A water strider can walk across the surface of a small pond

Why does ice float in liquid water?

Hydrogen bonds stabilize and keep the molecules of ice farther apart than the water molecules of liquid water.

Nonpolar compounds such as oils and fats are classified as

Hydrophobic

One of the buffers that contribute to pH stability in human blood is carbonic acid (H2CO3). Carbonic acid is a weak acid that dissociates into a bicarbonate ion (HCO3-) and a hydrogen ion (H+). Thus, H2CO3 ↔ HCO3- + H+ If the pH of the blood drops, one would expect

a decrease in the concentration of H2CO3 and an increase in the concentration of HCO3-.

Unequal sharing of electrons between atoms will result in which of the following interactions?

a polar covalent bond

If a salamander clings to surfaces through hydrogen bonds, it would have the most difficulty clinging to which of the following surfaces?

a surface coated with a thin film of vegetable oil

Buffers are substances that help resist shifts in pH by

accepting H+ from a solution when acids are added

A paper clip can float on the surface of a beaker of water mainly due to

cohesion

Water molecules are able to form hydrogen bonds with

compounds that have polar covalent bonds

If the pH of a solution is increased from pH 5 to pH 7, it means that the

concentration of OH- is 100 times greater than what it was at pH 5.

Which of the following are the strongest molecular interactions?

covalent bonds

Conversion of liquid water to water vapor requires breaking which of the following types of bonds?

hydrogen bonds

Hydrophobic substances such as vegetable oil are

nonpolar substances that repel water molecules

A covalent bond is likely to be polar when

one of the atoms sharing electrons is much more electronegative than the other atom

A covalent chemical bond is one in which?

outer-shell electrons of two atoms are shared so as to occupy the outer electron shells of both atoms.

Many mammals control their body temperature by sweating. Which property of water is most directly responsible for the ability of sweat to lower body temperature?

the absorption of heat by the breaking of hydrogen bonds.

If the cytoplasm of a cell is at pH 7, and the interior of an organelle is pH 8, this means that

the concentration of hydrogen ions is tenfold higher in the cytoplasm than in the organelle.

The chemical behavior of an atom depends primarily upon which of the following?

the number of electrons in the valence electron shell