1.2 Water, Life's Solvent Flashcards
To learn and understand 1.2
Why is water referred to as the “universal solvent”?
Water is known as the “universal solvent” because of its ability to dissolve a wide variety of substances due to its polar structure and hydrogen bonding capabilities.
How many hydrogen bonds does each water molecule form on average in liquid water?
Each water molecule in liquid water forms an average of 3.4 hydrogen bonds with its neighboring water molecules.
What is the water lattice and how does it differ in liquid water versus ice?
The water lattice is how water molecules bond together. In liquid water, the bonds are loose and can break and reform, so molecules move around easily. In ice, the bonds are strong and form a solid structure, keeping the molecules in a fixed structure and therefore they are farther apart.
Why is ice less dense than liquid water?
Ice is less dense than liquid water because the rigid crystalline structure of ice spaces the water molecules farther apart than in liquid water. This makes them less tightly packed and therefore less heavy.
What impact would ice sinking have on Earth’s bodies of water?
If ice sank, it would accumulate at the bottom of oceans, lakes, and streams, which would disrupt aquatic life and alter the structure and function of these water bodies.
How would water’s boiling point change without hydrogen bonding, and what would be the implications?
Without hydrogen bonding, water would boil at −81°C. This would mean that most water on Earth would be in the gaseous state, making it impossible to drink, swim in, or have it inside our cells.
What is specific heat capacity and how does it relate to water’s thermal properties?
Specific heat capacity is the amount of thermal energy required to increase the temperature of a given quantity of water by one degree Celsius. Water has a high specific heat capacity because much of the thermal energy is used to break hydrogen bonds, allowing water to absorb a lot of heat before its temperature rises significantly.
What is cohesion and how does it affect water molecules?
Cohesion is the property of water molecules staying close together due to hydrogen bonding. This results in surface tension, making it difficult to stretch or break the surface of water and allowing small insects to walk on water.
What is adhesion and how does it benefit plants?
Adhesion is the ability of water molecules to form hydrogen bonds with other polar molecules. In plants, adhesion helps water molecules stick to the cell walls of xylem tubes, assisting in the transport of water from the roots to the leaves.
How do cohesion and adhesion work together in the transport of water in plants?
Cohesion helps water molecules stick together as they are transported through the xylem tubes, while adhesion helps water molecules stick to the cell walls of the tubes. This combination allows water to move effectively from the roots to the leaves and replace evaporated water.
What are hydrophilic molecules?
Hydrophilic molecules are attracted to water and are easily dissolved in it.
Why do ionic substances like sodium chloride dissolve easily in water?
Ionic substances dissolve easily in water because water molecules form hydration shells around the ions, reducing their attraction to each other and allowing them to separate from their crystal lattice. The hydration shell keeps the individual ions from re-forming into a solid state, keeping them dissolved.
What is a hydration shell?
A hydration shell is a layer of water molecules that surrounds polar or charged molecules or ions, reducing their attraction to each other and promoting their separation into solution.
What are hydrophobic molecules?
Hydrophobic molecules are not attracted to water and have low solubility in it.
How is the pH of a solution determined?
The pH of a solution is determined by the concentration of hydronium ions (H₃O⁺). A pH below 7 indicates acidity, while a pH above 7 indicates basicity.
