Earth Science Test 14

Water

A colorless, transparent, order less liquid made of molecules with 2 hydrogen atoms connected to 1 oxygen atom

Boiling Point

Temperature at which a substance turns from liquid to gas

Freezing Point

Temperature at which a substance turns from a liquid to a solid

Heating Curve

A graph showing the temperature and phases (solid, liquid, or gas) of a substance as its heated

Why does heating curve have places where the temperature doesn’t change?

When a substance is melting or boiling, energy added to it changes the phase of the matter (solid to liquid or liquid to gas) instead of increasing the temperature.

How does salt (sodium chloride) lower the freezing point of water?

Dissolved sodium and chlorine atoms get between water molecules so it’s hard for them to arrange into crystals.

Why does water expand (take up more space) when frozen?

As water freezes it forms hydrogen bonds between the water molecules which pouches the molecules farther apart from each other

Why is the expansion of ice important?

Ice is less dense than liquid water so the ice will float.

Surface Tension

A characteristic allowing the surface of some liquids like water to act like a strong, elastic skin that stops small items on the surface from sinking

What causes water to have a high surface tension?

Water molecules have a greater attraction to each other (called cohesion) than to the air. This causes them to pull together making a strong barrier at the water’s surface.

Cohesion

Water molecules have a strong attraction to other water molecules

Meniscus

The curved upper surface of liquids like water caused by surface tension and cohesion with the container

Why is cohesion of water important?

1. The attraction of water to itself causes it to form round drops such as rain inside of clouds.


1. Cohesion helps water move up plant stems because the molecules pull more water molecules up the plant.

Adhesion

Water molecules have a strong attraction to other substances

Why is adhesion of water important?

Water can “stick“ inside the stems of plants allowing it to flow upward from the roots to the leaves of plants.

Capillary Action

Movement of water inside a material due to adhesion and cohesion

Specific Heat Capacity

A measure of how much heat a substance stores before getting hot

What is the result of water’s high specific heat?

1. A water such as oceans and lakes heats up slowly and cool down slowly.

2. Land temperatures near water

3. The water in our bodies can absorb lots of heat without making us too hot to survive.

Polar

When different atoms in the same molecule have different positive and negative charges

Non - polar

When different atoms in the same molecule don’t have different positive and negative charges

How is the polarity of water important?

Water can dissolve many other substances.

Why don’t oil and water mix or dissolve together?

Oil which is non - polar doesn’t have positive or negative charges to attract to the positive and negative charges on a water molecule.

Why is water important to living things?

Water is the universal solvent.

Universal Solvent

A name for water because dissolves more substances than any other liquid

How do substances dissolve in water on Earth?

1. Fertilizer dissolves in rainwater allowing it to wash into rivers, lakes, and oceans causing pollutions.


1. Water can also contain dissolved oxygen which is absorbed from the water by animals with gills.

Oceans

97\.6% of Earth’s water found in very large expanses covering the Earth’s surface

Saline Lakes and Seas

0\.008% of Earth’s salt containing waters found in land - locked areas

Glaciers and Ice Caps

1\.9% of Earth’s water as ice sheets (freshwater) in mountains or near the poles

Groundwater

0\.5% of Earth’s water found underground in spaces in soil, sand, and rocks

Lakes

0\.009% of Earth’s water found as freshwater in areas surrounded by land

Freshwater Rivers and Streams

0\.0001% of Earth’s naturally running water that follows a well - defined path, usually within a valley

Water Vapor and Clouds

0\.0009% of Earth’s water found as a gas, liquid, and / or solid making up the clouds and humidity in the atmosphere

Desalination

The process of removing materials like salt from ocean water

How is desalination helpful?

It can provide people with drinking water and it can provide irrigation water to crops in dry areas.

How is desalination harmful?

Removing salt from ocean water increases the ocean’s salt concentration which can harm fish. It also makes pollution and is an expensive way to get water.

Divide

A high area that separates a landscape into different drainage basins

Drainage Basin

An area of land where precipitation drains downhill into a river, lake, wetland, or ocean

How do they make our city water safe?

1. Alum and lime added to river water clumps dirt so it sinks in the water.

2. The water is filtered through gravel, sand, and / or charcoal beds to remove dirt. Alum, gravel, sand, and charcoal can remove dirt but don’t remove or filter germs like bacteria. Lime reduces water hardness, makes water less acidic and helps kill bacteria.

3. Chlorine is added to disinfect water making it safe to drink.

4. Some water treatment plants add fluoride to water to help our teeth.

What problems are caused by drinking untreated water?

Illness such as cholera, dysentery, typhoid, typhoid, and polio are caused by bacteria or viruses spread by unsafe drinking water. Giardia is caused by a parasite found in drinking water contaminated with feced