chapter 3 Flashcards
(16 cards)
What partial charges do the atoms of water molecules carry?
Oxygen atom carries a partial negative charge (δ-); each hydrogen atom carries a partial positive charge (δ+).
What are the general properties of water?
Lower density as a solid, high heat of evaporation, high specific heat, good at dissolving hydrophilic molecules.
What is cohesion in the context of water?
Cohesion contributes to the transport of water and dissolved nutrients against gravity in plants.
What is adhesion in the context of water?
Adhesion is an attraction between different substances, for example, between water and plant cell walls.
How does water’s density change when it freezes?
In ice, the hydrogen bonds are stable, and the water molecules are farther apart, leading to lower density as a solid.
What is the role of water in temperature moderation?
Water absorbs heat from warmer air and releases stored heat to cooler air; it resists changing its temperature due to high specific heat.
What is the specific heat of a substance?
The amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1ºC.
What does it mean for water to be a versatile solvent?
Water can dissolve many hydrophilic substances, such as ionic compounds and polar molecules.
Define hydrophilic substances.
Hydrophilic substances interact with water and can dissolve in water.
Define hydrophobic substances.
Hydrophobic substances do not interact with water and do not dissolve in water, clustering together.
What happens to the pH of a solution as hydrogen ion concentration increases?
The pH value decreases, making the solution more acidic.
What is the relationship between pH and hydrogen ion concentration?
Higher pH means lower concentration of H+ and higher concentration of OH-. Lower pH means higher concentration of H+ and lower concentration of OH-.
How does hydrogen ion concentration change with pH units?
Every 1 number lower means 10 times more H+; every 1 number higher means 10 times less H+.
What is a buffer?
Buffers are chemicals (acids and bases) that maintain the pH of a solution or environment within normal limits.
How do buffers function in the human body?
Buffers minimize changes in pH by taking up excess hydrogen ions (H+) and hydroxide ions (OH-).
What is the role of buffers in maintaining pH levels in the body?
Buffers maintain a stable pH level within the blood and cells by absorbing or releasing hydrogen ions (H+) to counteract changes in acidity or alkalinity.
