Properties of Water

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Questions and Answers

What is the specific heat capacity of water primarily responsible for?

Allowing sand to retain heat longer than water

Increasing the rate of evaporation in hot weather

Making water a poor conductor of heat

Minimizing temperature changes in the environment (correct)

How much heat is required to vaporize one gram of water at its boiling point?

100 cal/g

540 cal/g (correct)

212 cal/g

300 cal/g

What phenomenon occurs as water evaporates from a surface?

The surface temperature increases significantly

The surface remains unchanged in temperature

The surface cools down (correct)

The surface absorbs energy from the air

Which of the following statements about water's specific heat capacity is true?

Water has a high specific heat capacity compared to many other substances. Signup and view all the answers

Why do land areas cool faster than bodies of water at night?

Water has a higher specific heat capacity than land. Signup and view all the answers

What primarily causes water molecules to form hydration shells around solute molecules?

The polarity of water molecules Signup and view all the answers

Why do nonpolar substances such as oils not dissolve in water?

They lack regions of partial charge. Signup and view all the answers

What effect does freezing have on the density of water?

Frozen water is less dense than liquid water. Signup and view all the answers

What property of water requires significant heat input to raise its temperature?

Specific heat capacity Signup and view all the answers

How does the presence of ice on bodies of water affect the organisms below?

Ice provides insulation to protect against freezing. Signup and view all the answers

What feature of water molecules is primarily responsible for their ability to form hydrogen bonds?

The polarity of water molecules Signup and view all the answers

Which of the following statements about hydration shells is true?

Hydration shells disperse molecular solutes evenly in water. Signup and view all the answers

What happens to the density of water as it cools and approaches its freezing point?

It decreases and then increases as it freezes. Signup and view all the answers

What is cohesion in the context of water molecules?

Attraction of water molecules for other water molecules. Signup and view all the answers

What phenomenon is primarily responsible for the high surface tension of water?

Cohesive forces due to hydrogen bonding. Signup and view all the answers

What is capillary action?

The upward movement of water in thin tubes due to adhesion and cohesion. Signup and view all the answers

Why is water considered the 'universal solvent'?

It is particularly effective at dissolving ions and polar molecules. Signup and view all the answers

What accounts for the polar nature of a water molecule?

Unequal sharing of electrons, leading to partial charges. Signup and view all the answers

Which of the following statements about adhesion is true?

It refers to the attraction between different types of molecules. Signup and view all the answers

What role do cohesive and adhesive forces play in the biology of water transport?

They facilitate the movement of water up through plants. Signup and view all the answers

What occurs when water molecules are exposed to nonpolar substances?

Water molecules do not interact effectively. Signup and view all the answers

What is the reason for the bent shape of a water molecule?

The oxygen atom has unshared electron pairs that repel each other. Signup and view all the answers

Why is water classified as a polar molecule?

The oxygen atom attracts electrons more than hydrogen atoms. Signup and view all the answers

What type of bonding occurs between water molecules?

Hydrogen bonds Signup and view all the answers

What term describes substances that dissolve well in water?

Hydrophilic Signup and view all the answers

What best characterizes the cohesion of water molecules?

Water molecules sticking together due to hydrogen bonds Signup and view all the answers

What is the charge distribution within a water molecule?

Oxygen has a partial negative charge and hydrogen has a partial positive charge. Signup and view all the answers

What type of molecules do not interact well with water?

Nonpolar molecules Signup and view all the answers

Which of the following statements about water's properties is true?

Water's cohesive properties allow it to form a dome shape on surfaces. Signup and view all the answers

Study Notes

Water constitutes 60-70% of organisms, supporting life through unique chemical properties crucial to biology.

Polarity of Water Molecules

A water molecule comprises two hydrogen atoms bonded to one oxygen atom, creating a bent structure.
Oxygen's higher electronegativity attracts electrons closer to itself, resulting in a partial negative charge for oxygen and partial positive charges for hydrogen.
Water is a polar molecule due to its polar covalent bonds and bent shape.

Hydrogen Bonding

Polarity allows water molecules to attract each other, forming hydrogen bonds between the partial positive hydrogen atoms and the partial negative oxygen atoms.
Hydrogen bonds are weak and require the hydrogen atom to be attached to electronegative atoms like oxygen, nitrogen, or fluorine.
Water forms hydrogen bonds with other polar molecules and ions, exhibiting hydrophilic interactions.

Cohesion of Water

Water molecules exhibit strong cohesion due to hydrogen bonding, leading to surface tension, which allows water to form a dome shape on surfaces, such as a coin.
Cohesion is critical for phenomena like the ability of water striders to walk on water due to surface tension.

Adhesion of Water

Adhesion occurs when water molecules stick to different types of molecules, particularly polar ones, enabling capillary action.
Capillary action allows water to travel upward in capillary tubes, essential for nutrient transport in plants.

Solvent Properties of Water

Water is termed the "universal solvent" because of its ability to dissolve diverse solutes, particularly ions and polar molecules.
Polar water molecules form hydration shells around solutes, allowing for even dispersion in aqueous solutions.
Nonpolar substances, like oils, do not dissolve in water and instead remain separate, termed hydrophobic.

Density of Ice and Water

Ice has a lower density than liquid water due to the arrangement of hydrogen bonds, causing water to expand upon freezing.
Ice floats on liquid water, providing insulation for aquatic life during winter, as it forms a protective layer over bodies of water.

Heat Capacity of Water

Water exhibits a high specific heat capacity, requiring considerable energy to increase temperature due to hydrogen bond disruption.
It minimizes temperature changes in the environment, contributing to climate moderation and stable living conditions.

Heat of Vaporization of Water

Water's high heat of vaporization requires significant energy to transform liquid water into gas, around 540 cal/g at 100 °C.
As water evaporates, it cools the surrounding surface, exemplified by the cooling effect of sweat evaporation on the human body.

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Description

Explore the essential properties of water and their significance in supporting life. This study guide covers the molecular structure and unique chemical characteristics of water, highlighting its importance in biology from cellular to ecosystem levels.

Properties of Water - Study Notes