Podcast
Questions and Answers
Which of the following best describes the relationship between water's high specific heat and its ability to moderate temperature?
Which of the following best describes the relationship between water's high specific heat and its ability to moderate temperature?
- Water's high specific heat is independent of its ability to moderate temperature; it is primarily related to its high heat of vaporization.
- Water's high specific heat is directly related to its high boiling point, making it an effective solvent.
- Water's high specific heat allows it to absorb a large amount of heat energy before its temperature increases significantly, which helps to stabilize temperatures in living organisms. (correct)
- Water's high specific heat causes it to quickly release heat energy, which is important for maintaining consistent temperatures in living organisms.
Why does ice float on liquid water?
Why does ice float on liquid water?
- The crystal lattice structure of ice allows for greater hydrogen bonding, making it more dense than liquid water.
- Ice is more dense than liquid water due to the strong covalent bonds between the hydrogen and oxygen atoms.
- Ice is less dense than liquid water because the hydrogen bonds between water molecules in ice create a more open structure, increasing its volume for a given mass. (correct)
- The pressure at the bottom of water bodies causes ice to float, displacing the water.
Which of the following substances would likely have the HIGHEST specific heat?
Which of the following substances would likely have the HIGHEST specific heat?
- Glycerol
- Ammonia (correct)
- Methane
- Ethanol
Which of the following correctly describes the interaction between water and a nonpolar molecule?
Which of the following correctly describes the interaction between water and a nonpolar molecule?
What is the primary reason why water is an excellent solvent for many substances, including salts and sugars?
What is the primary reason why water is an excellent solvent for many substances, including salts and sugars?
Which of the following would have the lowest hydrogen ion concentration ([H+])?
Which of the following would have the lowest hydrogen ion concentration ([H+])?
A solution with a pH of 4 is how many times more acidic than a solution with a pH of 6?
A solution with a pH of 4 is how many times more acidic than a solution with a pH of 6?
Which of the following is NOT a characteristic of buffers?
Which of the following is NOT a characteristic of buffers?
How does the bicarbonate ion (HCO3-) act as a buffer in the blood?
How does the bicarbonate ion (HCO3-) act as a buffer in the blood?
What is the approximate pH range of a solution where a buffer system is most effective?
What is the approximate pH range of a solution where a buffer system is most effective?
Flashcards
Hydrogen bonds
Hydrogen bonds
Weak attractions between polar molecules, including water, allowing cohesion and adhesion.
Specific heat of water
Specific heat of water
The amount of heat needed to raise the temperature of 1g of water by 1°C, which is 1 calorie.
Heat of vaporization
Heat of vaporization
The energy required to convert 1g of water from liquid to gas, which is 586 cal.
Less dense ice
Less dense ice
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Hydrophobic exclusion
Hydrophobic exclusion
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pH Scale
pH Scale
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Acidic Solution
Acidic Solution
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Basic Solution
Basic Solution
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Buffer System
Buffer System
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Buffering Range
Buffering Range
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Study Notes
Water's High Heat of Vaporization Facilitates Cooling
- The heat of vaporization is the amount of energy required to change 1 gram of a substance from a liquid to a gas
- A considerable amount of heat energy is required to break the hydrogen bonds in water
- The evaporation of water from a surface cools that surface
- Many organisms cool by evaporative cooling (e.g., sweating)
Solid Water is Less Dense Than Liquid Water
- At low temperatures, water molecules are locked into a highly ordered, crystal-like structure held together by hydrogen bonds
- Ice is less dense than liquid water because the water molecules are relatively far apart, creating an open structure
- This unusual feature enables icebergs to float
- If water did not have this property, nearly all bodies of water would be ice, impacting aquatic life
Water's High Specific Heat Helps Maintain Temperature
- The temperature of a substance is a measure of how rapidly its individual molecules are moving
- A large amount of heat energy is required to break the hydrogen bonds in water
- This is why water has a high specific heat, defined as the amount of heat 1 gram of a substance must absorb or lose to change its temperature by 1 degree Celsius
- Water resists temperature changes, which is critical to maintaining relatively constant internal temperatures in organisms
Water's Solvent Properties Move Ions and Polar Molecules
- Water molecules gather closely around any substance that bears an electrical charge (ions or polar molecules)
- Water molecules form hydration shells around ions, preventing them from associating with other solute molecules
- Sugars and other polar molecules dissolve readily in water because they form hydration shells around them, also preventing them from associating with other solute molecules
Water Organizes Nonpolar Molecules
- Water molecules tend to form the maximum possible number of hydrogen bonds
- When nonpolar molecules are placed in water, they tend to aggregate or clump to exclude themselves from the water
- The nonpolar molecules minimize their disruptive effect on hydrogen bonding among water molecules
- Nonpolar molecules are called hydrophobic ("water-fearing")
- Polar molecules are called hydrophilic ("water-loving")
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