Questions and Answers
Why are water molecules polar?
Water molecules are polar because both hydrogen (positive) and oxygen (negative) atoms have opposite charges, making it a polar covalent bond and a polar molecule.
Explain why water molecules are capable of hydrogen bonding with 4 neighboring water molecules.
Because of the atoms in the water molecules. Hydrogen(+) and Oxygen(-) attach and disconnect with other oppositely charged water molecules creating multiple bonds.
What is cohesion?
Cohesion occurs when water molecules bond/form together, since the hydrogen and oxygen atoms are polar they have opposite charges that attract each other.
What is adhesion?
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Why does ice float on water?
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Why is water considered a great solvent?
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How do cohesion and adhesion contribute to the movement of water from the roots to the leaves of a tree?
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Distinguish between heat and temperature.
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Match the terms with their definitions: Solute, Solvent, Solution.
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Distinguish between hydrophobic and hydrophilic substances.
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Name the products of the dissociation of water and give their concentration in pure water.
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Define acid, base, and pH.
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How do you determine the pH of a solution if the concentration of hydrogen or hydroxide ions is known?
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How do acids and bases alter hydrogen ion concentration in a solution?
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What is the function of buffers, and give an example in the human body.
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Study Notes
Properties of Water
- Water molecules are polar due to the positive charge of hydrogen atoms and the negative charge of oxygen atoms, resulting in polar covalent bonds.
- Water can form hydrogen bonds with up to four neighboring water molecules because of the attraction between oppositely charged regions.
Cohesion and Adhesion
- Cohesion describes the attraction between water molecules, allowing them to form clusters due to polarity.
- Adhesion refers to water's ability to cling to other substances, facilitating the upward movement of water in plants against gravity.
Ice and Density
- Ice floats on liquid water because its solid form is less dense, an unusual property that allows aquatic life to survive beneath frozen surfaces.
Water as a Solvent
- Water's polarity makes it an excellent solvent. It can dissolve ionic compounds like salt by attracting and surrounding sodium and chloride ions.
Water Movement in Plants
- Water's cohesion maintains liquid integrity during transport through plant vessels, while adhesion aids in drawing water up from roots to leaves via evaporation.
Heat vs. Temperature
- Temperature measures the average kinetic energy of molecules, while heat is the thermal energy transferred between objects.
Solutions and Solutions Components
- A solute is a substance dissolved in a solvent. A solution is a homogeneous mixture of solutes and solvents.
Hydrophilic vs. Hydrophobic
- Hydrophilic substances, such as cotton, attract water despite not dissolving. Hydrophobic substances, like vegetable oil, repel water and do not mix with it.
Water Dissociation
- When water dissociates, it produces hydrogen and hydroxide ions at a concentration of 10^-7 M in pure water.
Acids, Bases, and pH
- Acids increase hydrogen ion concentration; bases decrease it. pH measures this concentration, ranging from 0 to 14.
Calculating pH
- To determine pH from known hydrogen or hydroxide ion concentrations, subtract the value from 14 on the pH scale.
Role of Acids and Bases
- Acids and bases influence hydrogen ion concentration directly through increase or decrease, affecting pH levels.
Function of Buffers
- Buffers stabilize pH by minimizing fluctuations in ion concentrations, with carbonic acid serving as a key buffer in the human body.
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Description
Explore the essential concepts of water molecules in this flashcard quiz from Biology Chapter 3. Discover why water is a polar molecule and its unique ability to form hydrogen bonds with neighboring molecules. Perfect for reinforcing your understanding of molecular biology!