Chapter 16: Water

CFE 001, Sp26

Properties of Water

High density for a liquid, expands when it freezes

Amphoteric

act as either an acid or a base

Is water amphoteric

Yes

Does water have a high heat vaporization

Yes, large amount of heat required to vaporize a small amount of water

Specific Heat

Specific heat is the amount of energy necessary to raise the
temperature of 1 g of water by 1 °C.

Heat equation

q = mCΔT

q

heat

m

mass

C

specific heat

ΔT

change in temperature

Earth surface

75% covered with water, 98% is seawater

Water Specific Heat Capacity

1.00

Earth’s water

2% is frozen in the polar ice caps

Natural contaminants in water

gases, dissolved minerals, organic matter

Gases

radon, nonmetal oxides, and others

Dissolved minerals

cations and anions, calcium, magnesium, and iron salts causes hard water

Organic Matter

Bacteria, microorganisms, and animal wastes are all potential contaminants of natural waters

Acid Rain

sulfur and nitrogen oxides (SOx and NOx)

Eutrophication

aging

BOD

Biochemical oxygen demand

What causes eutrophication?

human waste, runoff from farm and lawns, human activity

Methemoglobinemia

Infant consumption of water turning blue and die

Nitrates (NO3^-)

fertilizer (nitrogen)

VOCs

Volatile Organic Chemicals

Volatile Organic Chemicals (VOCs)

contaminates ground water

PPM

Parts per million

PPB

Parts per billion

Chlorine

Kills bacteria

Ozone

bacterial disinfection, kills many viruses

Ultraviolet (UV) light

disinfect water, effective in small-scale applications

Fluorides

Added into water to help prevent tooth decay

Hydroxyapatite

tooth enamel composed of calcium phosphate

Primary sewage treatment

holding sewage in settling ponds to allow heavier solids to precipitate out as sludge

Secondary sewage treatment

passing effluent from the primary treatment through sand and gravel filters

Aerobic bacteria

break down of organic matter

Tertiary treatment

further treatment of sewage, charcoal filtration to absorb organic molecules

Sludge

can be used as fertilizer

volume was water increases as it freezes

True

Which is NOT a property of water?

It has lower density than most liquids do

Why high specific heat of water important to Earth

Helps moderate earth temperatures fluctuations

% of freshwater Earth has

2

Soft water

contains relatively large concentrations of sodium ions

Human activity that contributes to BOD

dumping detergent in a lake or pond

Aerobic decomposition of organic matter requires…

oxygen