Podcast
Questions and Answers
Each water molecule is joined to _____ other water molecules by ____ bonds.
Each water molecule is joined to _____ other water molecules by ____ bonds.
Each water molecule is joined to _____ other water molecules by ____ bonds.
Each water molecule is joined to _____ other water molecules by ____ bonds.
Each water molecule is joined to _____ other water molecules by ____ bonds.
Each water molecule is joined to _____ other water molecules by ____ bonds.
four...hydrogen
The unequal sharing of electrons within a water molecule makes the water molecule _____.
The unequal sharing of electrons within a water molecule makes the water molecule _____.
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The tendency of an atom to pull electrons toward itself is referred to as its _____.
The tendency of an atom to pull electrons toward itself is referred to as its _____.
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In this molecule, what type of bond is found between the oxygen and hydrogens?
In this molecule, what type of bond is found between the oxygen and hydrogens?
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Which of these bonds is weakest?
Which of these bonds is weakest?
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Why isn't this insect drowning?
Why isn't this insect drowning?
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Which statement must be mentioned in explaining why amphipathic molecules line up at a water surface?
Which statement must be mentioned in explaining why amphipathic molecules line up at a water surface?
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Dissolving is best described as...
Dissolving is best described as...
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Water is a source of ______________ for chemical reactions in cells.
Water is a source of ______________ for chemical reactions in cells.
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Which statement is true of water's tensile strength?
Which statement is true of water's tensile strength?
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Water has surface tension because...
Water has surface tension because...
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Which of the following helps most to explain why water has a high specific heat?
Which of the following helps most to explain why water has a high specific heat?
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Which factor is important in making it possible to cool yourself by sweating?
Which factor is important in making it possible to cool yourself by sweating?
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Though you add heat, the temperature of boiling water remains constant because...
Though you add heat, the temperature of boiling water remains constant because...
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Which statement helps to explain why ice is less dense than liquid water?
Which statement helps to explain why ice is less dense than liquid water?
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The open spaces in water's crystal structure make it possible for...
The open spaces in water's crystal structure make it possible for...
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Why doesn't oil mix with water?
Why doesn't oil mix with water?
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Many of water's emergent properties, such as its cohesion, its high specific heat, and its high heat of vaporization, result from the fact that water molecules _____
Many of water's emergent properties, such as its cohesion, its high specific heat, and its high heat of vaporization, result from the fact that water molecules _____
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Because organisms are made primarily of water, they resist rapid temperature changes. This useful quality is based on water's _____.
Because organisms are made primarily of water, they resist rapid temperature changes. This useful quality is based on water's _____.
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In a neutral solution the concentration of _____
In a neutral solution the concentration of _____
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How does the pH of the solution on the right compare with that of the solution on the left?
How does the pH of the solution on the right compare with that of the solution on the left?
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A pH of 6 is how many times more acidic than a pH of 9?
A pH of 6 is how many times more acidic than a pH of 9?
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Select the statement that best describes a buffer.
Select the statement that best describes a buffer.
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Which statement is true of pH buffers?
Which statement is true of pH buffers?
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A buffer consists of undissociated acid (HA) and the ion made by dissociating the acid (A-). How does this system buffer a solution against decreases in pH?
A buffer consists of undissociated acid (HA) and the ion made by dissociating the acid (A-). How does this system buffer a solution against decreases in pH?
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Buffers work best when...
Buffers work best when...
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How does the way a buffer stabilizes pH during addition of acid differ from the way the same buffer stabilizes pH during addition of base?
How does the way a buffer stabilizes pH during addition of acid differ from the way the same buffer stabilizes pH during addition of base?
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Which answer helps to explain why all living cells need pH buffers?
Which answer helps to explain why all living cells need pH buffers?
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To make a buffer, you need to...
To make a buffer, you need to...
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Which property of water allows dogs to cool themselves by panting?
Which property of water allows dogs to cool themselves by panting?
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What is the difference between H+ concentration in an acidic solution such as lemon juice (pH 2) and a basic solution such as household bleach (pH 13)?
What is the difference between H+ concentration in an acidic solution such as lemon juice (pH 2) and a basic solution such as household bleach (pH 13)?
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Study Notes
Water Molecule and Properties
- Water molecules form four hydrogen bonds with other water molecules, contributing to its unique properties.
- The polarity of water results from unequal sharing of electrons, leading to partial positive and negative charges.
- Electronegativity refers to an atom's ability to attract electrons towards itself, influencing chemical bonding.
- Bonds in water include polar covalent bonds between oxygen and hydrogen atoms.
Physical Properties of Water
- Surface tension allows insects to walk on water due to the cohesive properties arising from hydrogen bonds.
- Amphipathic molecules line up at water surfaces because polar groups attract each other.
- Dissolving involves a mixing process of molecules or ions, highlighting water's solvent capabilities.
- Water acts as a source of hydrogen and oxygen atoms for chemical reactions in cells.
Specific Heat and Temperature Regulation
- Water's high specific heat stems from the ability to form four hydrogen bonds, making it resistant to temperature changes.
- Sweating cools the body as it utilizes the relatively weak hydrogen bonds that break during evaporation.
- The temperature of boiling water remains constant despite heat addition because energy is required to break hydrogen bonds.
Density and Ice Formation
- Ice is less dense than liquid water due to the specific angles of hydrogen bonds that create open space in its crystal structure.
- This property allows aquatic life to thrive underneath ice-covered surfaces.
Interaction with Other Substances
- Water does not mix with oil because polar and non-polar molecules have different interactions, with polar molecules preferring to associate with each other.
- Many of water's emergent properties, such as cohesion and high heat of vaporization, result from the attraction between charged molecules.
pH and Buffers
- In neutral solutions, hydrogen ion concentration equals hydroxide ion concentration.
- A pH of 6 is 1,000 times more acidic than a pH of 9, indicating significant differences in acidity.
- Buffers resist changes in pH by interacting with hydrogen ions; they consist of weak acids and bases.
- The buffering system enhances stability in solutions by reacting to additions of acids and bases, ensuring organisms maintain appropriate pH levels.
- Amino acid side chains in cells possess carboxyl and amino groups that necessitate the presence of pH buffers.
Practical Applications of pH Buffers
- Effective buffers are made from weak acids or bases that are partially ionized in water, stabilizing pH during chemical reactions.
- The functionality of a buffer depends on having a balanced ratio of dissociated and undissociated molecules for optimal performance.
Unique Properties of Water
- Dogs can cool down by panting due to water's high heat of vaporization, which facilitates evaporative cooling.
- The H+ concentration in acidic solutions like lemon juice (pH 2) is exponentially higher than in basic solutions like bleach (pH 13) by a factor of 10^11.
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Description
Test your knowledge of key concepts from Chapter 3 of MasteringBiology. This quiz covers essential topics such as water molecules, polarity, and electronegativity. Perfect for students looking to reinforce their understanding of biology fundamentals.
