Water

Aquarium Safety

It is unsafe to clean an aquarium while the heater is plugged in due to electrocution risk.

Transferring Bacteria

Fish can carry bacteria like Salmonella that are harmful to humans.

Aquarium Maintenance

Do not clean the filter and change the water on the same day to preserve beneficial bacteria.

Safety Equipment for Lab Experiments

Wear goggles, gloves, and closed-toe shoes; avoid loose clothing and open shoes.

Water Coverage on Earth

Approximately 71% of the Earth is covered in water.

Saltwater Percentage

About 97% of Earth's water is saltwater.

Usable Water Percentage

Less than 1% of the Earth's water is available for human use.

Water Composition in Human Body

Around 60–70% of the human body is made of water.

Hydrosphere

All the water on Earth, including oceans, lakes, rivers, groundwater, glaciers, and atmosphere.

Polarity of Molecules

A polar molecule has an uneven distribution of charge with positive and negative ends.

Cohesion

Attraction between water molecules themselves.

Adhesion

Attraction between water molecules and other substances.

Surface Tension

A 'skin-like' surface formed by the cohesion of water molecules.

Transpiration

The process of water movement through plants and evaporation from leaves.

Capillary Action

Movement of water through narrow spaces due to cohesion and adhesion.

Electronegativity

The tendency of an atom to attract electrons in a bond.

Hydrogen Bonds in Water

Hydrogen bonds are intermolecular forces between water molecules.

High Heat Capacity of Water

Water can absorb large amounts of heat without significant temperature changes.

Density Order of Water

From least to most dense: Ice → Hot Water → Warm Water → Room Temperature Water → Cold Water.

Behavior of Hot Water

Hot water rises to the top when mixed with room-temperature water because it is less dense.

Why Ice Floats

Ice floats because hydrogen bonding makes it less dense than liquid water.

Raising Water Temperature

To raise water temperature, molecules must move faster, increasing kinetic energy.

Thermocline

A layer in water where temperature changes rapidly with depth; absent at the poles.

Benefits of Water as a Heat Sink

Regulates climate, stabilizes ecosystems, and protects aquatic life from temperature extremes.

Archimedes' Principle

The buoyant force on an object is equal to the weight of the fluid it displaces.

Forces on Flotation

Gravity acts downwards while buoyant force pushes upwards.