Water and Its Properties

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Questions and Answers

Why is water important to life?

Water plays a crucial role in various biological processes and makes up a significant portion of all living organisms.

What shape is a water molecule?

A wide 'V' shape.

How do polar covalent bonds affect water molecules?

They create an uneven distribution of charge, making water a polar molecule.

Hydrogen bonds in water are stronger than covalent bonds.

False Signup and view all the answers

What is cohesion in the context of water?

Cohesion refers to water molecules sticking together due to hydrogen bonds. Signup and view all the answers

What does surface tension refer to?

The ability of water molecules to stay together and resist external forces. Signup and view all the answers

How does water moderate temperature?

Water absorbs heat from warmer air and releases stored heat to cooler air. Signup and view all the answers

What is the difference between heat and temperature?

Heat is the total kinetic energy of molecules, while temperature is the average kinetic energy of those molecules. Signup and view all the answers

What happens when two objects of different temperatures are brought together?

Heat passes from the warmer object to the cooler one until they reach the same temperature. Signup and view all the answers

What is a calorie?

The amount of heat it takes to raise the temperature of 1 g of water by 1°C. Signup and view all the answers

What is the specific heat of water?

1 calorie per gram per degree Celsius. Signup and view all the answers

Water's specific heat is low compared to most other substances.

False Signup and view all the answers

Why does a large body of water warm up only a few degrees during the day?

Because it can absorb and store a huge amount of heat from the sun. Signup and view all the answers

Ice is denser than liquid water.

False Signup and view all the answers

A liquid that is a completely homogeneous mixture of two or more substances is called a ______.

solution Signup and view all the answers

Which of the following is a hydrophilic substance?

Sugars Signup and view all the answers

What are hydrophobic substances?

Water-hating Signup and view all the answers

Study Notes

Water and Its Properties

Water is crucial for life on Earth.
Most cells contain 70% to 95% water.
Water molecules are polar because of the unequal sharing of electrons between oxygen and hydrogen atoms.
Hydrogen bonds form between water molecules due to the attraction between the partial positive charge of a hydrogen atom in one molecule and the partial negative charge of an oxygen atom in another molecule.
Hydrogen bonds are weaker than covalent bonds but are still important for water's properties.

Four Properties of Water Crucial for Life

Cohesion: Water molecules stick together due to hydrogen bonding. This helps trees draw water from the roots to the leaves.
Surface Tension: Water molecules resist external forces due to cohesion which allows some insects to walk on water.
Moderation of Temperature: Water absorbs heat from warmer air and releases heat to cooler air, moderating temperature. This is important for living organisms.
Ability to absorb and release heat: Water can absorb or release a large amount of heat with only a slight change in its own temperature. This is due to the hydrogen bonds that require a lot of energy to break.

Other Key Facts

Heat is a measurement of the total kinetic energy of a substance.
Temperature is the average kinetic energy of the molecules in a substance.
A larger body of water can hold more heat than a smaller one even if they have the same temperature.
When objects of different temperatures come in contact, heat flows from the warmer object to the cooler one.
Evaporation is the process by which a liquid changes into a gas. Evaporation cools the liquid and releases heat into the environment.
Condensation is the process by which a gas changes into a liquid. Condensation releases heat into the environment.

Water's Role in Life

Water's Properties: Water's unique properties stem from its molecular structure.
Water is made up of two hydrogen atoms and one oxygen atom, forming covalent bonds.
- These bonds are polar, with oxygen being more electronegative than hydrogen, meaning it pulls electrons towards itself.
Water molecules form hydrogen bonds with each other due to the electronegativity difference between oxygen and hydrogen atoms.
Heat Capacity: Water's high specific heat means it requires a large amount of heat to change its temperature. Its specific heat is 1 calorie per gram per degree Celsius (1 cal/g.°C).
- Significance for Life: Water's high specific heat helps stabilize temperature fluctuations, both in the environment and in organisms. This allows for life to thrive in a stable temperature range.
Density of Ice: Water expands when it freezes, making ice less dense than liquid water.
- Significance for Life: This allows ice to float on water, providing an insulating layer for aquatic life.
Water as a Solvent: Water is a highly versatile solvent, capable of dissolving many compounds, including ionic and polar covalent compounds.
- Significance for Life: Water's solvent property allows for the transport of nutrients and waste products within organisms.
Hydrophilic and Hydrophobic Substances:
- Hydrophilic: These substances are "water-loving" because they can form hydrogen bonds with water, making them soluble in water.
- Hydrophobic: These substances are "water-hating" because they do not dissolve in water due to their non-polar nature and inability to form hydrogen bonds.
pH and Living Organisms:
- Acidic: Solutions with a pH less than 7 are considered acidic.
- Basic (Alkaline): Solutions with a pH greater than 7 are considered basic.
- Importance: The pH of a solution can affect the function of enzymes, cell membranes, and other biological processes.

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Description

Explore the essential properties of water that enable life on Earth. This quiz covers the significance of water's structure, hydrogen bonding, and its unique behaviors such as cohesion and surface tension. Test your understanding of how these properties affect living organisms.