Property of Water

Why is water considered a polar molecule?

Water is polar because oxygen is more electronegative than hydrogen, creating partial negative and positive charges. This allows water to interact with other polar molecules.

What is cohesion, and how does it help water?

Cohesion is the attraction between water molecules due to hydrogen bonding. It creates surface tension, allowing insects to walk on water.

What is adhesion, and how is it useful in nature?

Adhesion is the attraction between water and other substances. It helps water climb up plant stems (capillary action) by sticking to the xylem walls.

Why does ice float on water?

Ice floats because water expands when it freezes, forming a lattice structure that makes it less dense than liquid water. This allows aquatic life to survive in winter.

How does water’s high specific heat capacity affect the environment?

Water absorbs a lot of heat before changing temperature, which helps regulate climate by keeping temperatures stable in oceans and lakes.

Why does sweating cool down the body?

Water has a high heat of vaporization, meaning it takes a lot of energy to evaporate. When sweat evaporates, it absorbs body heat, cooling you down.

Why is water called the "universal solvent"?

Water dissolves many polar and ionic substances, like salt and sugar, but not nonpolar substances like oil. This is important for nutrient transport in living things.

How does salinity affect the freezing point of water?

Higher salinity lowers the freezing point because salt disrupts hydrogen bonding, making it harder for water to freeze. This is why seawater freezes at -2°C instead of 0°C.

How does adding salt to water change its density?

More salt = higher density. This is why saltwater is denser than freshwater and why objects float more easily in the ocean.

What two properties of water make capillary action possible?

Cohesion and adhesion. Cohesion keeps water molecules together, while adhesion helps them stick to surfaces, allowing water to move up narrow tubes like plant xylem.

What type of bond holds multiple water molecules together?

Hydrogen bonds form between water molecules due to the attraction between the partially positive hydrogen and the partially negative oxygen.

Why does water have a high boiling point compared to other similar-sized molecules?

Water has a high boiling point because of strong hydrogen bonding, which requires a lot of energy to break the bonds and turn liquid water into gas.

What is the pH of pure water, and why is it important?

The pH of pure water is 7 (neutral). This balance is crucial for maintaining stable conditions in biological systems and chemical reactions.

Why does water rise higher in thinner tubes than in wider ones?

In thinner tubes, adhesion forces pull water up more efficiently, while cohesion helps form a continuous column. This is why water rises higher in narrow plant xylem.

Why does alcohol evaporate faster than water, even at the same temperature?

Alcohol has weaker hydrogen bonds than water, so it takes less energy to break them, causing it to evaporate faster.

Why do objects float better in saltwater than in freshwater?

Saltwater is denser than freshwater, so it provides more upward force (buoyancy), making it easier for objects to float.

Why does cold water hold more oxygen than warm water?

In cold water, molecules move slower, allowing more gas molecules (like oxygen) to dissolve and stay in solution.

Why does breaking a large water droplet into smaller droplets speed up evaporation?

Smaller droplets have more surface area, allowing more molecules to escape into the air, increasing the evaporation rate.

Why does water flow more easily than honey, even though both are liquids?

Water has low viscosity because its molecules move freely, while honey has stronger molecular interactions, making it flow more slowly.

Why does water feel colder than air at the same temperature?

Water has higher thermal conductivity, meaning it transfers heat away from your body faster than air, making it feel colder.

Why does water become more dense under high pressure?

Under high pressure, water molecules pack closer together, slightly increasing density. This is why deep ocean water is denser than surface water.

How does water help with diffusion in living organisms?

Water acts as a medium for diffusion, allowing substances like oxygen, carbon dioxide, and nutrients to move easily through cells and tissues.

Why don’t oil and water mix?

Oil is nonpolar, while water is polar. Water molecules are more attracted to each other than to oil molecules, causing them to separate instead of mixing.

What is osmosis, and why is it important in cells?

Osmosis is the movement of water across a membrane from a low solute concentration to a high solute concentration. It helps cells maintain balance and hydration.

Why does water move through soil, even against gravity?

Capillary action allows water to move through small spaces in soil due to cohesion and adhesion, helping plants absorb groundwater.

Why is water transparent, and why is this important for life?

Water’s transparency allows sunlight to pass through, which is essential for photosynthesis in aquatic plants and algae.

What happens when an acid is added to water?

The acid releases hydrogen ions (H⁺) into the water, lowering the pH and making it more acidic.

How does water help create ocean tides?

Water is affected by the gravitational pull of the Moon and Sun, causing high and low tides due to changes in water level.

Why is water important in the human circulatory system?

Blood is mostly water, allowing it to transport oxygen, nutrients, and waste efficiently throughout the body.

How does water behave differently than most substances when it freezes?

Most substances shrink when they freeze, but water expands due to its hydrogen-bonded structure, making ice less dense than liquid water.