Water, Water EVERYWHERE! SOL 6.5

Importance of Water Lesson 1

Why is water important to life? Biological Functions Warming Earth Keeping Earth’s Temperatures Stable

Biological Functions Water is necessary for the life processes of all living things. Water transports materials such as nutrients to cells. Water is needed for any chemical reactions that occur in organisms. (photosynthesis) Water keeps the body temperature from becoming too high or low.

Warming Earth Water vapor in the Earth’s atmosphere is one of the gases that cause the greenhouse effect. In the greenhouse effect, Earth’s atmosphere traps thermal energy from the Sun. Without the greenhouse effect, Earth’s temperature would be much colder.

Keeping Earth’s Temperature Stable Water helps keep the Earth’s temperature stable because water has a high specific heat. Specific heat is the amount of thermal energy needed to raise the temperature of 1 kg of a material by 1°C. Water vapor helps control the rate at which air temperature changes.

Water on Earth Most of Earth’s waters is in the oceans. Only 3% is freshwater. Freshwater is at the Earth’s surface, in the ground, and in the icecaps and glaciers.

Structure of the Hydrosphere The hydrosphere is all the water on and below Earth’s surface and in the atmosphere. Groundwater is water below the Earth’s surface. In the atmosphere, water vapor forms tiny droplets in clouds. Water in the solid state is located near Earth’s poles in glaciers as ice. Atmosphere Groundwater

Water Changes State Water is the only substance that exists in nature in three states – solid, liquid, and gas. When water changes from one state to another, thermal energy is either absorbed or released. Thermal energy always moves from a warmer object to a cooler one.

Water Changes State Between a solid and Liquid Ice changes to water at the melting point (0°C) of water. For ice to melt, it must absorb energy. Water changes to ice at the freezing point (0°C) of water. For water to freeze, it must release energy.

Between Liquid and Gas Liquid water changes to water vapor at the boiling point (100°C) of water. Liquid water can change to water vapor at temperatures below the boiling point during evaporation. For water vapor to change to liquid water, the water vapor must release energy. Condensation is the process of a gas changing to a liquid.

Water Cycle The water cycle is a natural process by which water constantly moves throughout the hydrosphere. The two main factors that drive the water cycle are: the Sun and gravity Water on Earth’s surface evaporates because of thermal energy from the Sun. Some water evaporates from plants during transpiration.

Water Cycle Process As water vapor from transpiration and evaporation rises in the atmosphere, it cools and condenses into a liquid. Eventually precipitation, such as rain and snow, falls back to Earth. On Earth’s surface, gravity causes water to flow downhill. Runoff is water from precipitation that flows over Earth’s surface. Water is stored on Earth in reservoirs.

Key Terms Evaporation -the process of a liquid changing to a gas at the surface of the liquid Transpiration – the evaporation of water from plants. Condensation – the process by which water vapor (gas) cools and collects and turns back into liquid water Precipitation – water, in the liquid or solid form, that falls from the atmosphere Runoff – water that flows over the Earth’s surface

Properties of Water Lesson 2

Water is a unique compound The structure of a molecule of water determines the properties of water. Water is made up of 2 parts hydrogen and 1 part oxygen. Chemical symbol is H2O One special property of water is its high specific heat.

Why is water unique? Polar Molecule Surface Tension Capillary Action Change in State Universal Solvent

Water is a polar molecule A polar molecule is a molecule that has electrically charged areas The positive hydrogen ends of one water molecule attract the negative oxygen ends of nearby water molecules allowing them to stick together. This process is called cohesion.

Surface Tension Surface Tension is the tightness across the surface of water resulting from the cohesion by the polar molecules pulling on and sticking to each other

Capillary Action When molecules that are not alike are attracted to each other it is through the process of adhesion. Capillary Action is the adhesion or combined force of attraction among water molecules and with the molecules of surrounding materials. This allows water to move through materials with pores or narrow spaces inside.

Changing States of Water Water is the only substance on Earth that commonly exists in all of its 3 different states!!!!

Water is the Universal Solvent Water is called the universal solvent because so many substances dissolve in water. A solution is a mixture that forms when one substance dissolves another. The substance that does the dissolving is called the solvent. The substance being dissolved is called the solute.