Bio 101: Chapter 3

What is the charge on a hydroxide ion?

1-

Why does ice float in liquid water? Stable hydrogen bonds keep water molecules of ice farther apart than water molecules of liquid water. The high surface tension of liquid water keeps the ice on top. The crystalline lattice of ice causes it to be denser than liquid water. The ionic bonds between the molecules in ice prevent the ice from sinking.

Stable hydrogen bonds keep water molecules of ice farther apart than water molecules of liquid water.

What are these examples of? A sewing needle floats when it is placed gently on top of water in a bucket, and a water strider runs across a pond without breaking the surface

Surface tension

Why isn't this insect drowning? The insect is swimming. The insect is very light. The insect is flying just above the water surface. It is difficult to change the temperature of water. Surface tension.

Surface tension

The unequal sharing of electrons within a water molecule makes the water molecule _____. The unequal sharing of electrons within a water molecule makes the water molecule _____. hydrophobic polar have a low surface tension ionic change easily from a liquid to gaseous form

polar The electrons spend more time with the oxygen of the water molecule than with the hydrogens of water. Thus, the oxygen has a net negative charge and the hydrogens have a net positive charge.

In this molecule, what type of bond is found between the oxygen and hydrogens? polar covalent hydrophilic ionic nonpolar covalent hydrophobic

polar covalent While oxygen shares electrons with hydrogen, the electrons spend more time with the oxygen than with the hydrogens.

About _____ molecules in a glass of water are dissociated.

1 in 500,000,000

What is the charge on a hydronium ion?

1+

What are these examples of? Water molecules cling to the side of a beaker, and water molecules cling to plant cell walls

Adhesion

What are these examples of? Water molecules are attracted to each other, and a drop of water spilled on a table forms a drop on the table, rather than spreading out over the surface

Cohesion

If the pH of a solution is decreased from 9 to 8, it means that the concentration of _____.

H+ has increased tenfold (10X) compared to what it was at pH 9 H+ has increased tenfold (10X) compared to what it was at pH 9

Which of these is the correct equation for the dissociation of water?

H2O + H2O <==> H3O+ + OH-

A water molecule gained an hydrogen ion from another water molecule.

How did this molecule form? Evaporation. Two water molecules bonded. A water molecule gained an hydrogen ion from another water molecule. A hydrogen molecule bonded with an OH- molecule. A water molecule split in half.

hydronium ion A water molecule that gains a hydrogen becomes a hydronium ion.

What name is given to this molecule? methane hydroxide ion hydronium ion glucose water

hydroxide ion

What name is given to this molecule? hydronium ion DNA glucose hydroxide ion water

The tendency of an atom to pull electrons toward itself is referred to as its _____. The tendency of an atom to pull electrons toward itself is referred to as its _____. electronegativity covalency polarity tonicity ionic potential

electronegativity

Each water molecule is joined to _____ other water molecules by ____ bonds. a) two ... polar covalent b) three ... ionic c) four ... polar covalent d) two ... hydrogen e) four ... hydrogen

four ... hydrogen As can be seen in the illustration on page 1 of the activity titled "The Polarity of Water" a water molecule is joined to four other water molecules by hydrogen bonds.

Which of the following solutions would require the addition of the greatest amount of base to bring the solution to neutral pH?

gastric juice at pH 2

Hydrophobic substances such as vegetable oil are _____. attraction for water molecules polar substances that have an affinity for water polar substances that repel water molecules nonpolar substances that repel water molecules

nonpolar substances that repel water molecules