Ch 3 - Water - BIO 200

Measurements show that the pH of a particular lake is 4.0. What is the hydrogen ion concentration of the lake?

10-4 M

Label the following diagram of water molecules, indicating the location of bonds and the partial charges on the atoms. Drag the labels to their appropriate locations on the diagram of the water molecules below. Labels can be used once, more than once, or not at all.

A - covalent bond B - δ - C - hydrogen bond D - δ + E - δ + F - covalent bond G - δ - H - hydrogen bond

Why isn't this insect drowning?

Surface Tension

The unequal sharing of electrons within a water molecule makes the water molecule _____.

polar

Identify all correct statements about the ionization of water. Check all that apply.

- Dissociation of water is reversible. - Water ionizes to form hydroxide and hydronium ions. - Dissociation of water produces equal numbers of OH- and H+.

The table shown here lists the specific heat of several substances. Which of the following statements are true?

- Sulfuric acid is less resistant to temperature change than water. - More heat is required to raise the temperature of 1 g of water 1 - Benzene is more resistant to temperature change than sulfuric acid. - Water has a high specific heat due to the hydrogen bonding between water molecules. Submit

Classify each statement as an example of adhesion, cohesion, or surface tension. Drag each statement to the appropriate bin.

Adhesion: -Water molecules cling to the side of a beaker. -Water molecules cling to plant cell walls. Cohesion: -Water molecules are attracted to each other -A drop of water spilled on a table forms a drop on the table, rather than spreading out over the surface. Surface tension: -A sewing needle floats when it is placed gently on top of water in a bucket. -A water strider runs across a pond without breaking the surface.

Which of these bonds is weakest?

Hydrogen Bonds are weaker than covalent bonds because they do not involve sharing of electrons, and they are weaker than ionic bonds because they involve the attraction of partial (not full) opposite charges.

In this molecule, what type of bond is found between the oxygen and hydrogens? (H2O molecule)

Polar covalent (While oxygen shares electrons with hydrogen, the electrons spend more time with the oxygen than with the hydrogens.)

How does the pH of the solution on the right compare with that of the solution on the left?

The solution on the right is basic relative to the solution on the left.

The tendency of an atom to pull electrons toward itself is referred to as its _____.

electronegativity

What process exerts the pull on water molecules that is relayed from leaf to root via cohesion?

evaporation

A water molecule can bond to up to _____ other water molecules by ____ bonds.

four ... hydrogen

What is the arrow pointing to?

hydrogen ion

In a neutral solution the concentration of _____.

hydrogen ions is equal to the concentration of hydroxide ions

What is the arrow pointing to?

hydroxide ion

We can be sure that a mole of table sugar and a mole of vitamin C are equal in their

number of molecules.