Chapter 3: Water and Life Flashcards
True or false; Oxygen is more electronegative than hydrogen.
True
How does water exhibit its properties?
Through hydrogen bonding.
What are the four emergent properties of water?
1.) Cohesion
2.) Moderation of temperature
3.) Expansion upon freezing
4.) Versatility as a solvent
What is cohesion?
The linking together of molecules, often by hydrogen bonds.
What is a result of cohesion due to hydrogen bonding?
Surface tension
What is surface tension?
A measure of how difficult it is to stretch or break the surface of a liquid.
What is adhesion?
The clinging of one substance to another. ex. water to plant cell walls
True or false; water has a very low specific heat.
False; water has a very high specific heat.
What is specific heat?
the amount of heat that must be absorbed or lost for 1g of that substance to change it’s temperature by 1°C
What causes ice to float?
Molecules become locked into a crystalline lattice, keeping them far enough apart to make it less dense than liquid water.
True or false; water is a universal solvent.
False; water is a VERSATILE solvent
What does it mean if a substance is hydrophilic?
It has an affinity for water.
What does it mean if a substance is hydrophobic?
The substance repels water. ex. vegetable oil
What is a hydrogen ion? (H+)
A single proton with a charge of plus one. One of the resultants of water dissociation.
What is a hydroxide ion? (OH-)
A water molecule that has lost a proton. One of the resultants of water dissociation.
What is a hydronium ion? (H3O+)
A water molecule that has an extra proton bound to it.
True or false; dissociation of water is not reversible.
False; water dissociation is reversible, but is statistically rare.
What is an acid?
A substance that increases the hydrogen ion concentration of a solution. (H+)
What is a base?
A substance that reduces the hydrogen ion concentration.
True or false; pH decreases as H+ concentration increases.
True
What is a buffer?
a substance that minimizes changes in the concentrations of H+ and OH- in a solution.
How does a buffer work?
It accepts hydrogen ions to the solution when they have been depleted, minimizing the concentrations of H+ and OH- in a solution.
