AP Biology Chapter 3 Flashcards

Questions and Answers

Why is water polar?

Oxygen is more electronegative than hydrogen, making oxygen negatively charged and hydrogen positively charged.

Why is water's polarity significant?

It contributes to the fitness of the Earth including cohesion, temperature stabilization, expansion upon freezing, and versatility as a solvent.

What does cohesion mean?

Holding a substance together.

What does adhesion mean?

Clinging of a substance to another. Signup and view all the answers

What is capillary action?

The attraction of the surface of a liquid to the surface of a solid, causing the liquid to rise or fall. Signup and view all the answers

What is surface tension?

A measure of how difficult it is to break or stretch a surface. Signup and view all the answers

What is kinetic energy?

Energy of motion. Signup and view all the answers

What is heat?

Total kinetic energy due to molecular motion. Signup and view all the answers

What is a calorie?

Amount of heat it takes to move 1 gram of substance 1 degree Celsius higher. Signup and view all the answers

What is temperature?

Intensity of heat due to average kinetic energy. Signup and view all the answers

What is specific heat?

Amount of heat needed to be absorbed or lost to change the temperature by 1 degree Celsius. Signup and view all the answers

What is the specific heat of water?

1 calorie/1 gram/1 degree Celsius. Signup and view all the answers

How does high specific heat of water affect temperature in large bodies of water?

It can absorb huge amounts of heat at night while gradually cooling, warming the air. Signup and view all the answers

What is evaporative cooling?

When the remains of a liquid cool down. Signup and view all the answers

What is vaporization?

Amount of heat needed to turn liquid into gas. Signup and view all the answers

What is evaporation?

Process of liquid becoming gas. Signup and view all the answers

What is the result of water's high heat of vaporization?

Stability of temperatures in lakes and ponds. Signup and view all the answers

What happens to the density of water as temperature decreases?

Water behaves like other liquids until 4 degrees Celsius, then it expands as it freezes, leading to lower density. Signup and view all the answers

How does the density of water contribute to aquatic life?

If ice sank, bodies of water would freeze solid, killing life. Signup and view all the answers

What is a solution?

A liquid completely homogeneous of two or more substances. Signup and view all the answers

What is a solvent?

Dissolving agent. Signup and view all the answers

What is a solute?

Substance dissolved. Signup and view all the answers

What is an aqueous solution?

Water is the solvent. Signup and view all the answers

What is a hydration shell?

Sphere of water molecules around dissolved ions. Signup and view all the answers

What are hydrophobic/philic substances?

Water loving/water hating. Signup and view all the answers

What is molecular weight?

Sum of all atoms. Signup and view all the answers

What is a mole?

The molecular weight of a substance expressed in grams (6.02 x 10^23). Signup and view all the answers

What is molarity?

Concentration measured by the number of moles per liter of solution. Signup and view all the answers

What is a hydrogen ion?

H+. Signup and view all the answers

What is a hydroxide ion?

OH-. Signup and view all the answers

What is a hydronium ion?

H3O+. Signup and view all the answers

What are acids?

Substances that increase H+ concentration. Signup and view all the answers

What are bases?

Substances that reduce H+ concentration. Signup and view all the answers

What are strong acids and bases?

Completely ionized when dissolved in water. Signup and view all the answers

What are weak acids and bases?

Only partly ionized in their solutions. Signup and view all the answers

What is the pH scale?

Measures concentration of H+ (scale from 1-14). Signup and view all the answers

What are buffers?

Substances that minimize changes in H+/OH- concentration. Signup and view all the answers

What is the extent of acid precipitation?

The presence of sulfur oxides/nitrogen oxides and gaseous compounds reacts with water. Signup and view all the answers

Study Notes

Water's Polarity

Water is a polar molecule because oxygen is more electronegative than hydrogen, causing unequal electron sharing.
This polarity leads to a more negatively charged oxygen atom and positively charged hydrogen atoms.

Importance of Water's Polarity

The properties of water, such as cohesion, temperature regulation, expansion upon freezing, and solvent versatility, derive from its polarity.
These characteristics support life and ecological balance on Earth.

Key Properties of Water

Cohesion: Attraction between water molecules, helping to hold them together.
Adhesion: Attraction between water molecules and other substances.
Capillary Action: Water's ability to rise or fall in narrow spaces due to adhesive forces.
Surface Tension: Resistance to being stretched or broken, allowing some organisms to walk on water.

Kinetic Energy: The energy of motion, related to the movement of particles.
Heat: Total kinetic energy resulting from molecular motion.
Calorie: The amount of heat required to raise the temperature of one gram of water by one degree Celsius.
Temperature: A measure of the average kinetic energy of particles in a substance.

Specific Heat

Specific Heat of Water: 1 calorie per gram per degree Celsius, allowing it to absorb significant heat without a large temperature change.
High specific heat regulates temperatures in large bodies of water, moderating climate and air temperatures.

Phase Changes and Cooling

Evaporative Cooling: Cooling that occurs when molecules with higher kinetic energy (heat) evaporate, leaving cooler molecules behind.
Heat of Vaporization: The amount of energy required to convert liquid to gas, contributing to the stability of temperatures in lakes and ponds.

Density and Water's Behavior

Water is unique in that it expands upon freezing, forming a crystalline structure that is less dense than liquid water.
The resulting ice floats, insulating the water below and protecting aquatic life during winter.

Solutions and Concentration

Solution: A homogeneous mixture of two or more substances.
Solvent: The substance that dissolves another (e.g., water).
Solute: The substance that is dissolved in a solvent.

Ion Concentration

Hydration Shell: A cluster of water molecules surrounding dissolved ions.
Hydrogen Ion (H+): A positively charged ion formed when an acid donates a proton.
Hydroxide Ion (OH-): A negatively charged ion present in basic solutions.
Hydronium Ion (H3O+): Formed when water accepts a hydrogen ion.

Acids and Bases

Acids: Substances that increase H+ concentration in solution.
Bases: Substances that reduce H+ concentration in solution.
Strong Acids/Bases: Fully ionize in water, releasing H+ or OH- completely.
Weak Acids/Bases: Only partially ionize and establish an equilibrium with their molecules.

pH Scale

The pH scale ranges from 1 to 14, measuring the concentration of H+ ions in a solution.
Buffers are substances that stabilize pH by minimizing changes in H+/OH- concentration, crucial for maintaining physiological conditions.

Environmental Impact

Acid precipitation arises from reactions of sulfur oxides and nitrogen oxides with atmospheric water, impacting ecosystems.

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Description

Dive into the essential concepts of water's polarity with these flashcards from Chapter 3 of Campbell's AP Biology. Understand how water's unique properties contribute to life on Earth, including its cohesion and temperature stabilization. Perfect for mastering key ideas in biology!