Water

Question 1

water is?

Answer 1

• the biological medium here on earth.
• all living organisms require it more than any other substance.
• 3/4th of the earths surface is submerged in water.
• the abundance of water is the main reason the earth is habitable.

Question 2

what kind of bond does the water molecule contain?

Answer 2

polar covalent bonds.
- this is because water has an uneven charge distribution.

Question 3

what does the polarity of water allow water molecules to do?

Answer 3

allows them to form hydrogen bonds with eachother.

Question 4

how many hydrogen bonds can each water molecule form with other water molecules?

Answer 4

4 hydrogen bonds.

Question 5

properties of water?

Answer 5

1. cohesion: cohesion is the joining together of many water molecules due to hydrogen bonding. this helps to pull water up through the water conducting cells of plants.
2. adhesion: adhesion is the clinging of one substance to another. water forms hydrogen bonds with other molecules such as the molecules that make up the cell walls of plants.
3. surface tension: measure of how hard it is to break the surface of a liquid. water has a very high surface tension.
4. water has a high specific heat: water can absorb or lose a large amount of heat before its own temperature is changed. (helps to stabilize water temperatures and because of this water can moderate air temperature).
5. water has a high heat of vaporization: amount of energy required to change 1g of it from liquid to gas.
6. solvent: water is an excellent solvent. any charged or polar molecule can be dissolved in water.

Question 6

solvent vs solute?

Answer 6

a solvent is the dissolving agent and the solute is what is being dissolved.

Question 7

if nacl is in a beaker of water, what happens?

Answer 7

the oxygen in water will be attracted to the na cations and the hydrogen in water will be attracted to the cl anions.
- the salt will dissolve and this will result in a solution.
- a solution is a liquid that is a homogenous mixture of 2 or more substances.

Question 8

what is a hydrophilic substance?

Answer 8

a hydrophilic substance has an affinity for water. (substances that are charged or polar).

Question 9

what is a hydrophobic substance?

Answer 9

a hydrophobic substance does not have an affinity for water. (substances that are not charged and nonpolar).

Question 10

acid?

Answer 10

any substance that increases the hydrogen ion concentration of a solution.
example: hcl

Question 11

base?

Answer 11

any substance that reduces the hydrogen ion concentration of a solution.
example: naoh

Question 12

ph scale?

Answer 12

0-14
if the ph is low, high concentration of hydrogen ions.
if the ph is high, low concentration of hydrogen ions.
ph of 7: neutral
ph under 7: acidic
ph over 7: basic