Chapter 3 - Water Flashcards
What are the properties of water?
Cohesion
Moderation of Temperature by water
Floating of Ice on Liquid Water
Very good solvent
What can cohesion do?
Hydrogen bonds allows for the transport of water in plants. (Allows trees to suck water from ground)
Cohesion is related to surface tension. (Allows bugs to crawl accross water or water to go above the level of your cup.)
Why is there a moderation of temperature by water?
- Because water has a high level of specific heat
- Evaporative cooling (like swamp coolers)
- It does this to help life exist in bodies of water
How and why does ice float on water?
The solid form of water is less dense than that of liquid form.
This happens because the hydrogen bonds are frozen and are stuck. It creates a magnetic field and will try to stay away as far as possible from the other atoms. This will create spaces usually filled with oxygen.
Define: Hydrophilic
Any substance that has an *affinity for water.
*a spontaneous or natural liking or sympathy for someone or something.
Define: Hydrophobic
Substances that are nonionic and nonpolar (or otherwise cannot form hydrogen bonds) actually seem to repel water.
Why is water a great solvent?
- Most biological chemistry consists of diluted dissolved in water as the solvent.
- Water can dissolve most anything
Define: Acid
An acid is a substance that increases the hydrogen ion concentration of a solution.
Define: Base
A substance that reduces the hydrogen ion concentration of a solution
What is the pH scale?
A pH scale is a scale that was created because of the vast differences in H+ concentrations a scale was made from 0 to 14 to express relative acidity or alkalinity.
If a substance is below 7 on a pH scale that means…?
It is more acidic (has more H+; donate H+ in aqueous solutions)
If a substance is greater than a 7 on a pH scale that means…?
It is more basic (has more OH-; donate OH- or accept H+ in aqueous solutions)
What are some examples of neutral substances on a pH scale?
Pure water, human blood, tears
What is a Buffer?
A substance that minimizes changes in the concentrations of H+ and OH- in a solution.
Ex. Human blood is a buffer.
Ex. Carbonic acid which is formed when CO2 reacts with water in blood plasma. If the H+ concentration in the blood begins to fall (pH rises), the reaction proceeds to the right and more carbonic acid dissociates, trying to replenish the hydrogen ions.
