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.
- four...polar covalent
- two...polar covalent
- four...hydrogen (correct)
- three...ionic
- two...hydrogen (correct)
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 _____.
- change easily from a liquid to gaseous form
- polar (correct)
- have a low surface tension
- ionic
- hydrophobic
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 _____
electronegativity
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?
Which of these bonds is weakest?
Which of these bonds is weakest?
Why isn't this insect drowning?
Why isn't this insect drowning?
What would a good student reply to Dr. Haxton's statement about hydrogen bonds?
What would a good student reply to Dr. Haxton's statement about hydrogen bonds?
Which statement is part of the explanation for water's high cohesion?
Which statement is part of the explanation for water's high cohesion?
Despite its cohesion, water can flow because...
Despite its cohesion, water can flow because...
Which answer helps to explain how many hydrogen bonds a water molecule can form?
Which answer helps to explain how many hydrogen bonds a water molecule can form?
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?
Dissolving is best described as...
Dissolving is best described as...
Water is a source of ______________ for chemical reactions in cells.
Water is a source of ______________ for chemical reactions in cells.
Which statement is true of water's tensile strength?
Which statement is true of water's tensile strength?
Water has surface tension because...
Water has surface tension because...
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?
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?
Though you add heat, the temperature of boiling water remains constant because...
Though you add heat, the temperature of boiling water remains constant because...
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?
The open spaces in water's crystal structure make it possible for...
The open spaces in water's crystal structure make it possible for...
Why doesn't oil mix with water?
Why doesn't oil mix with water?
A solution contains only glycerol and fructose. There is ten times as much glycerol as fructose. Therefore...
A solution contains only glycerol and fructose. There is ten times as much glycerol as fructose. Therefore...
A solution is aqueous if...
A solution is aqueous if...
A 1 M solution contains...
A 1 M solution contains...
Based on the information in the table, which of the following statements are true?
Based on the information in the table, which of the following statements are true?
In a neutral solution the concentration of _____.
In a neutral solution the concentration of _____.
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?
What name is given to this molecule?
What name is given to this molecule?
How did this molecule form?
How did this molecule form?
What name is given to this molecule?
What name is given to this molecule?
Which of these is the correct equation for the dissociation of water?
Which of these is the correct equation for the dissociation of water?
What is the charge on a hydronium ion?
What is the charge on a hydronium ion?
What is the charge on a hydroxide ion?
What is the charge on a hydroxide ion?
About _____ molecules in a glass of water are dissociated.
About _____ molecules in a glass of water are dissociated.
Which answer is a true statement about pH values?
Which answer is a true statement about pH values?
What conditions must be met in order for an aqueous solution to be called "neutral"?
What conditions must be met in order for an aqueous solution to be called "neutral"?
Factory smoke has led to acid rain that lowered the pH of a lake to 5.0. What is the H+ concentration in the lake?
Factory smoke has led to acid rain that lowered the pH of a lake to 5.0. What is the H+ concentration in the lake?
Your tank of swamp fish needs a pH of 5, and the pH is 7 at present. What should you do to the H+ concentration?
Your tank of swamp fish needs a pH of 5, and the pH is 7 at present. What should you do to the H+ concentration?
In a washing machine, the detergent raised the pH to 9.0. The concentration of OH- in the solution is...
In a washing machine, the detergent raised the pH to 9.0. The concentration of OH- in the solution is...
Your tank of alkali fish needs a pH of 8, and the pH is 6 at present. What should you do to the H+ concentration?
Your tank of alkali fish needs a pH of 8, and the pH is 6 at present. What should you do to the H+ concentration?
Study Notes
Water Molecule Characteristics
- Each water molecule forms hydrogen bonds with four other water molecules.
- Water's unequal electron sharing leads to its polar nature, giving oxygen a net negative charge and hydrogens a net positive charge.
Bond Types
- The bond between oxygen and hydrogen in a water molecule is identified as a polar covalent bond.
- Hydrogen bonds are weaker compared to covalent or ionic bonds, leading to unique properties of water.
Surface Tension and Cohesion
- Water's high surface tension allows small insects to remain on the surface, a result of cohesive hydrogen bonds.
- Cohesion in water is largely due to the electronegativity difference between oxygen and hydrogen which allows for hydrogen bonding.
Water's Behavior and Properties
- Water can flow because hydrogen bonds break and re-form rapidly, permitting relative movement of water molecules.
- The specific structure of water enables it to maintain high cohesion and tensile strength, essential for its movement in plants.
Thermal Properties
- Water has a high specific heat due to its capacity for forming multiple hydrogen bonds, requiring more energy to change its temperature.
- During boiling, the temperature remains constant as added energy is used to break hydrogen bonds rather than increase the temperature.
Ice and Density
- Ice is less dense than liquid water because of the open lattice structure formed by hydrogen bonds at specific angles, allowing ice to float.
- The presence of these open spaces in ice facilitates aquatic life to survive beneath frozen surfaces.
Solutions and Miscibility
- Water is known as a solvent in aqueous solutions, which contain a higher concentration of water compared to other substances.
- In solutions, the solute is the minor component while the solvent is the major component.
pH and Ion Concentrations
- A neutral solution has equal concentrations of hydrogen ions (H⁺) and hydroxide ions (OH⁻).
- The pH level affects the concentration of H⁺ ions; for instance, reducing the pH from 7 to 5 entails increasing H⁺ concentration 100 times.
Key Ionic Species
- The hydronium ion (H₃O⁺) is formed when a water molecule gains a hydrogen ion, while a hydroxide ion (OH⁻) results from a water molecule losing a hydrogen ion.
- The dissociation of water can be represented as: H₂O + H₂O ↔ H₃O⁺ + OH⁻.
Impacts of pH Changes
- Acid rain can lower the pH of water, affecting its chemistry and living organisms.
- Detergents can increase the pH in solutions, thus altering the concentration of hydroxide ions based on the pH scale.
Acid-Base Relationships
- For each unit change in pH, the concentration of H⁺ ions changes tenfold, affecting biological systems and chemical reactions.
- The balance between hydronium and hydroxide ions is crucial for maintaining neutral pH in biological systems.
Studying That Suits You
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Description
Test your knowledge of water molecules and their properties with these flashcards from Chapter 3. Focus on understanding the types of bonds that connect water molecules and the concept of polarity. Enhance your comprehension of fundamental chemistry concepts through interactive learning.
