CAPE Chemistry Unit 2 Module 3: Water

1. Module 3: Industry and the environment
Topic: Water
Institution: M.B.C.C
Lecturer: Ms. M. Manning

2.  Le-Jay K. Robinson
 Ethan Gayle
 Yakiene Shaw
 Patrick Miller

3.  Describe the importance of the water
cycle
 Discuss methods of water purification
 Discuss the importance of dissolved
oxygen to aquatic life
 Discuss the sources of water pollution

5.  Is the cycle of processes by which water
circulates between the earth's oceans,
atmosphere, and land, involving
precipitation as rain and snow, drainage
in streams and rivers, and return to the
atmosphere by evaporation and
transpiration.

7.  Evaporation- the changing of a liquid
into a gas, often under the influence of
heat (as in the boiling of water)
 Transpiration- process by which water
that is absorbed by plants is evaporated
into the atmosphere from the plant
surface, such as leaf pores (stomata).

8.  Condensation- is the change of water
from its gaseous form (water vapor) into
liquid water.
 Precipitation- rain, snow, sleet or hail that
falls to or condenses on the ground.
 Infiltration- is the process by which water
on the ground surface enters the soil.

10.  Regulates the temperature of the earth by
absorbing and circulating heat.
 Replaces water lost by lakes, rivers oceans
which are habitats for many organisms.
 Provides freshwater for drinking, agriculture,
industry and domestic use.

12.  is the process of removing undesirable
chemicals, biological contaminants,
suspended solids and gases from
contaminated water. The goal is to
produce water fit for a specific purpose.
 Methods include:, distillation, ion
exchange, filtration, chemical treatment,
UV radiation and desalinisation.

13.  the action of purifying a liquid by a process
of heating and cooling.
 It removes a wide range of contaminants
such as bacteria, sodium chloride, heavy
metals and organic compounds.
 Equipment is relatively inexpensive.
 Process is slow and requires large amounts
of energy.

15.  In this process, water percolates through
a column of spherical resin beads. The
ions in the water are exchanged for the
ions fixed to the beads.
 Ion-exchange methods include:
softening, deionization and electro-
deionization.

16.  Water softening is the removal
of calcium, magnesium, and certain
other metal cations in hard water.
 As hard water percolates through the
column, the calcium and magnesium
ions are exchanged for the absorbed
sodium ions on the resin beads. This can
be represented by the following
equation:

17. Ca2+
(aq) + 2Na-resin → Ca-resin + 2Na+
(aq)
 The resins can be regenerated by
washing with concentrated aqueous
sodium chloride. This can be represented
by the following equation:
Ca-resin + 2NaCl(aq) → 2Na-resin +CaCl2(aq)

19.  Removes dissolved minerals from water.
The ion-exchange resins contain
absorbed acid or alkali. The acidic resins
exchange hydrogen ions for cationic
contaminants while the alkaline resin
exchanges the hydroxyl ions for anionic
contaminants in water. The resins are
regenerated by washing with alkali or
acid.

20.  Electro-deionization is a water treatment
method that utilizes electricity in ion
exchange membranes and resins to
deionize water and separate dissolved ions
(impurities) from water.
 Unlike softening and deionization, this
method inhibits the growth of bacteria that
can attach to the resins and remove most
organic compounds and microbes.

21.  Filtration is the mechanical or physical
operation which is used for the
separation of solids from fluids (liquids or
gases) by interposing a medium through
which only the fluid can pass.
 Filtration techniques include: screen
filters, sand filters, carbon filters and
membrane filtration.

22.  A screen filter is a type of filter using a
rigid or flexible screen to separate fine
particles out of water for irrigation or
industrial applications.
 The screen is made of metal, plastic or
synthetic fiber mesh.

24.  Sand filters are layers of sand or other
suitable granular material used to
reduce suspended solids from water.
 As the water moves vertically through
the sand, suspended solids are trapped
in the sand.

26.  Carbon filtering is a method of filtering that
uses a bed of activated carbon
(charcoal) to remove contaminants and
impurities (VOC’s/Chlorine), using chemical
absorption.
 It also catalyses the conversion of chlorine
to chlorides and hydrogen sulphide to
sulphates which reduces undesirable
odours and tastes in water.

28.  The membrane separation process is
based on the presence of semi
permeable membranes. The principle is
quite simple: the membrane acts as a
very specific filter that will let water flow
through, while it catches suspended
solids and other substances.

29.  Reverse osmosis uses an external
pressure to force water through a
membrane that retains the solute on one
side and allows the pure water to pass
through the other side. The process
forces water to a region of high solute
concentration to a region of low solute
concentration.

32.  Desalinisation is the process of removing
salt or other minerals from saline water.
The two main methods used are
distillation and reverse osmosis.
 In this process freshwater and
concentrated brine is produced. Brine is
water strongly impregnated with salt.

36.  Oxygen is needed by aquatic life to
survive because it needed for them to
respire. Dissolved oxygen in water is
measured in pats per million (ppm) and
range from 0-18. Most natural water
require 5-ppm of dissolved oxygen to
support a variety of aquatic life. If
dissolved oxygen falls to 3-5ppm aquatic
life forms become stressed. Anything
below 2ppm results in death.

37.  Respiration- increase in aerobic
respiration decreases oxygen
concentration dissolved in water. This
caused by introduction of untreated
sewage which increases microbial
respiration.
 Temperature- as temperature increases,
the amount of oxygen dissolved in water
decreases.

38.  Eutrophication- Excess nutrients in water
can stimulate algal growth on the surface
of water. When these plants die, bacteria
use dissolved oxygen in the water for
decomposition.

40.  This is sewage from homes and
commercial establishments.
 In developing countries, an estimated
90% of wastewater is discharged directly
into rivers and streams without treatment.
This causes the spread of diseases such
as diarrhea, cholera and tuberculosis.

41.  Phosphates from laundering water
enhances algal bloom which also causes
eutrophication.
 Dumping of garbage such as plastic
packaging materials and synthetic fibers
can entangle, injure and kill aquatic
animals.

42.  Fertilizers, herbicides and pesticides used
in agriculture can be washed into
waterways by the action of rainfall or
irrigation. The increase in nutrient
content enhances algal growth which
causes eutrophication.
 Herbicides and pesticides which are
washed into ground water sources can
remain in the water for many years.
Consumption of this water can cause
varying illnesses such as diarrhea,
vomiting, etc.

43.  Nuclear waste- nuclear power stations
produce radioactive waste which pollutes
water.
 Oil spills- oil spills can degrade the quality
of water and suffocate marine life.
 Lead- this can enter the environment from
smelting, car batteries and plumbing
industries. If this enters the system of a living
organism it can cause varying effects.

44.  Mercury- mercury can environment as
waste from burning of coal and mining. If
it accumulates in an organism, it can
cause nervous system damage.
 Mining- this is the extraction of naturally
occurring minerals from the earth. In
doing this toxic heavy metals and other
compounds are released into the
environment.