Physical Science Quarter 2 Module
A renewable energy source is any natural resources that replaces at the same rate on
which the resource is used. A non-renewable energy source is any natural source that forms at
a rate that is much lower than the rate that it is consumed.
1. Fossil fuels are combustible materials that took millions of years to form underneath the earth.
It is a general term for buried combustible geologic deposits of organic materials, formed from
decayed plants and animals that have been converted to crude oil, coal, natural gas, or heavy
oils by exposure to heat and pressure in the earth’s crust over hundreds of millions of years.
2. Biogas is produced by the anaerobic decomposition of organic materials brought about by
certain varieties of bacteria. It burns to generate heat and used in combustion engines to produce
electricity.
3. Geothermal energy is the heat obtained from underneath the earth and carried to the surface
as steam. Work is being done on geothermal systems that pump hot water into underground
hotspots and then use the resulting steam to generate electricity.
4. Hydrothermal energy is the process of obtaining heat or energy from a large body of water.
Water in dams or from waterfalls are the most common sources of hydrothermal energy.
5. Batteries are voltaic cells that undergo electrochemical processes to produce electrical energy.
It includes dry cells, lead and storage batteries and fuel cells.
6. Solar cells are usually used for powering homes. These cells directly convert incoming radiant
energy from the sun into usable form. Sunlight is directly converted to electrical energy.
7. Biomass is any organic matter available on a renewable basis. The biomass of wood is
burned directly to provide heat and energy
Activity 1
Directions: List down examples of renewable and non-renewable resources that can be found
in your home.
Renewable Resources
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
NATURAL RESOURCES
Non-renewable Resources
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Activity 2
Directions: Write down the pros and cons of the energy resource illustrated below.
1. Coal
Advantages:____________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________.
Disadvantages:
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
___________________________________________________________________.
2. Animal Manure
Advantages:____________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________.
Disadvantages:
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
___________________________________________________________________.
Physical Science Quarter 2 Module
CHEMISTRY is the science that deals with the properties, composition, and structure of
substances (defined as elements and compounds), the transformations they undergo, and the
energy that is released or absorbed during these processes (Usselman, 2019). It is also
concerned with the utilization of natural substances. Through the use of modern technology,
artificial substances can also be created that expanded its scope and relevance.
Chemistry has different processes. Dating back from the beginning of civilization, these
processes have been undertaken by man. Examples of these processes are cooking,
fermentation, glass making, and metallurgy.
This 20th century, Chemistry has made man’s daily living more advanced in health by
curing diseases through molecular analysis and interpretations. Using the different processes of
chemistry, man has changed and has improved his daily routines from complex to simple ones.
Take for instance, washing of soiled clothes. Before, man has to use brush, wooden planks, and
herbs to soften the dirt. Today, the use of appropriate laundry detergent and bleach help reduce
the process of washing the clothes.
Another
example
of
how
Chemistry
helps
man
live
a
more sustainable and healthier lifestyle, is in the maintenance of the cleanliness of the household.
Imagine a house full of dirt, dust, stains and the dirt has invited the flies, mites, and cockroaches
all over your rooms and kitchen. Cleaning the dirt with simple water and cloth alone will take a
longer period of time and will require so much energy to completely do the job. The knowledge
on chemical compounds and substances, their properties and their used greatly helped to ease
man’s job on cleaning and in keeping the environment a safer place to live in.
Defining relevant concepts
An acid is classified as a compound with distinctive properties. An acidic substance is
sour-tasting; reacts with litmus paper, bases and metals; conducts electricity; and has a pH of
less than 7. An acid can be classified as strong or weak based on its reactivity, conductivity, and
pH.
pH Scale – is used as a measure of how acidic or basic a substance is. This scale ranges
from 0 to 14; a pH of 7 means the substance is neutral. An acidic substance measures lower on
the pH scale. A substance with a pH value less than 7, is acidic.
Litmus paper strips are used as a general indicator to determine acidity. When dipped
in or rubbed on an acidic substance, blue litmus paper turns red.
An Alkali or chemical base is a caustic substance. It is a substance that accepts
hydrogen ions. It dissociates in water and is a good conductor of electricity. An alkali turns litmus
paper blue.
Acids and bases are generally chemically active and can react in many other substances.
Because of this characteristic, they are commonly found in household applications, especially as
cleaners and as ingredients in cooking.
Understanding the properties of the chemical ingredients active in the following
cleaning materials:
1. Sodium hypochlorite appears as colorless or slightly yellow watery liquid with an odor of
household bleach. It mixes with water. (USCG, 1999). It is used as a bleaching agent, laundry
bleaching agent, disinfectant for glass, ceramics, and tiles.
2. Sodium bicarbonate appears as odorless white crystalline powder or lumps with slightly
alkaline (bitter) taste. It is used to make many chemicals, as an ingredient in baking powder,
effervescent salts and beverages, in fire extinguishers, cleaning compounds, and in human and
veterinary pharmaceuticals. Workers that use sodium bicarbonate may breathe in mists or have
direct skin contact. Sodium bicarbonate is a Generally Regarded as Safe (GRAS) chemical at
levels found in consumer products, and has a low risk of toxicity in humans. It is a slight skin and
eye irritant.
3. Sodium hydroxide room temperature is a white crystalline odorless solid that absorbs
moisture from the air. It is a manufactured substance. When dissolved in water or neutralized with
acid it liberates substantial heat, which may be sufficient to ignite combustible materials. Sodium
hydroxide is very corrosive. It is generally used as a solid or a 50% solution. Other common
names include caustic soda and lye. It is used to manufacture soaps, rayon, paper, explosives,
dyestuffs, and petroleum products. It is also used in processing cotton fabric, laundering and
bleaching, metal cleaning and processing, oxide coating, electroplating, and electrolytic
extracting. It is commonly present in commercial drain and oven cleaners. When inhaled, cough,
sore throat, burning sensation and shortness of breath may be experienced.
4. Boric acid is a white crystalline solid with a density of 1.435 g/mL, melting point of 170.9 °C
and boiling point of 300 °C. It is a weak inorganic acid with antiseptic properties, and is also called
boracic acid or orthoboric acid. It is non-toxic with antibacterial properties, and it is mainly used
as an antiseptic agent, acne treatment, preservative, insecticide, pH buffer, swimming pool
chemical, flame retardant, and a precursor to many useful chemicals.
5. Hydrochloric acid is colorless - light yellow in appearance, has a pungent and irritating odor,
has a pH level 0, with boiling point of 108.58°C @ 760 mm Hg (for 20.22% HCl in water) and
melting point at -62.25°C (20.69% HCl in water), soluble in cold and hot water and diethyl ether,
and it conducts electricity. Although it is highly corrosive, it is used to remove stains from metals.
It can clean iron, copper, brass and other metals; however, one should dilute it by adding 9 parts
of water to 1 part of the acid. One should not use it directly on metals as it is extremely powerful
cleaning agent.
6. Formaldehyde is a liquid which is clear or water-white. The odor is irritating and pungent. It is
soluble in water and up to 55 percent soluble in ether, acetone, benzene, and alcohol. Its melting
point is -92.0 °C and its boiling point is 19.5° C. An aqueous solution of formaldehyde can be
useful as a disinfectant as it kills most bacteria and fungi (including their spores).
7. Sodium Lauryl Sulfate appears as white to pale yellow paste or liquid with a mild odor, sinks
and mixes with water, (USCG, 1999) naturally derived from coconut and/or palm kernel oil. It
usually consists of a mixture of sodium alkyl sulfates, mainly the lauryl. SLS lowers surface tension
of aqueous solutions and is used as fat emulsifier, wetting agent, and detergent in cosmetics,
pharmaceuticals and toothpastes. It is also used in creams and pastes to properly disperse the
ingredients and as research tool in protein biochemistry. SLS also has some microbicide activity.
It is used in electrophoretic separation of proteins and lipids; wetting agent, detergent, especially
in the textile industry.
8. Ethanol is a clear, colorless liquid rapidly absorbed from the gastrointestinal tract and
distributed throughout the body. It has bactericidal activity and is used often as a topical
disinfectant. It is widely used as a solvent and preservative in pharmaceutical preparations as well
as serving as the primary ingredient in alcoholic beverages.
Activity 3
Identifying Common Household Cleaners
Directions: Take a tour at your house. List down at least five (5) examples of cleaning consumer
products that are usually used in your household and write them down in the table below. Read
the labels of the cleaning products and identify the active ingredient of each. Apply the cleaning
substance on a dirty surface. Examine its effect on the surface, then identify the use of the active
ingredient you identified in the substance.
Cleaning Substance
Active Ingredient
Use of Active Ingredient
1.
2.
3.
4.
5.
Answer the questions that follow using a separate sheet of paper. Discuss your answers
with your teacher-facilitator.
1. What is the active ingredient used in each cleaning solution?
2. Use the following cleaning solution in cleaning the following surfaces and determine if it is
sufficient to come up with an acceptable clean.
a. Bath soap in washing greasy pots
b. Borax in cleaning a goblet
c. Bleach in washing colored cloth
d. Hand soap in cleaning toilet bowls
3. Is there a particular chemical substance that is most appropriate to use in cleaning the
following? Identify the chemical. Why?
a. oven
c. garage
e. car
b. sink
d. bathroom tiles/toilet bowl
f. white linen
g. kitchen utensils
h. window panes
Table of Common Household Cleaning Materials
Common
Household Name
1. Bleach
Active chemicals
Product Application
Harmful Effects
Sodium hypochlorite
Used in washing
laundry, removing
stains
Ingestion can cause
injury to esophagus,
stomach irritation,
and prolonged
nausea and vomiting.
2. Boric acid
Boric acid
3. Borax
Sodium tetraborate
decahydrate
Used in products for
insecticide
Used as a
multipurpose cleaner
and bleach
Toxic if ingested or
inhaled
Long exposure can
cause respiratory
irritation
4. Caustic soda
Sodium hydroxide
Used in products for
cleaning, unblocking
sinks, drains and
even toilets. Highly
corrosive alkali
5. Formalin
40% solution of
formaldehyde
Used as disinfectant
or anti-bacterial
agent
Contact causes
severe burns with
redness, swelling,
pain and blurred
vision and blindness.
Ingestion can burn
lips, tongue, throat
and stomach.
Can cause skin
irritation; Toxic when
inhaled
6. Detergent
Sodium Lauryl
Sulfate & Sodium
Laureth
Sulfate/Sodium lauryl
ether sulfate
Used in laundry
detergents,
dishwashing liquids;
Can cause eye, skin,
or mouth irritation;
injury and death
when ingested;
Poisonous when
swallowed
7. Lye
Sodium hydroxide or
potassium hydroxide
Used as oven
cleaner
8. Algicides
Calcium and sodium
hypochlorite
Used as swimming
pool disinfectant
9. Air fresheners
Contain
formaldehyde,
petroleum distillates,
dichlorobenzene and
aerosol propellants.
Used to freshen cars,
bathrooms, etc.
Can burn skin and
eyes; cause severe
tissue damage; and
may be fatal if
swallowed
If swallowed, the
chemicals can burn
the throat and cause
death.
Can cause cancer
and brain damage;
irritate eyes, skin,
and throat.
Activity 1
Direction: Answer the following questions in a separate sheet of paper. Then discuss your
answers with your teacher-facilitator.
1. Based on the data given on the table, which cleaning material/s is/are
a. safe to use?
b. hazardous?
2. What active ingredients do air fresheners contain that may be hazardous to one’s health?
3. Will you still use the above cleaning agents in your homes?
4. What precautionary measures can be done in order to prevent harm to one’s body and avoid
death in using the chemical cleaning agents? List down at least five.
Example: 1. In using air fresheners, read the labels carefully and determine whether there are
no active ingredients like formaldehyde, petroleum distillates, p-dichlorobenzene and aerosol
propellants.
Physical Science Quarter 2 Module
HOW GREEKS KNOW THAT THE EARTH IS ROUND
Even before Plato, the Greeks have deduced that the Earth
is spherical based on the observation that the shadow cast by the
Earth during a lunar eclipse is circular and that the only shape that
can cast a circular shadow at whatever direction it is pointed is a
sphere. The Greeks were also able to measure the diameter of the
Earth. The Greeks also noted that the stars are viewed differently
as they travel north and south. Eratosthenes, a Greek
Mathematician, told that no vertical shadow was cast as the sun
rays fall vertically in the city of Syene in Egypt during summer
solstice. Eratosthenes noted that at the same time a shadow was
cast as the sun rays fell at an angle of 7.2° [one fiftieth (1/50) of a
circle in ancient Greek writings] in the city of Alexandria. He
assumed that the sun was so distant that the rays fall parallel to
each other on the Earth’s surface and that the difference in the
shadows cast in the two cities was due to the curvature of Earth’s round surface. The distance
between Syene and Alexandia was found to be 5000 stadia (approx. 800 km). Thus, Eratosthenes
thought the Earth’s circumference must be 50 x 5000 stadia or 250,000 stadia (40,000 kilometers).
Now, what is the significance of the spherical shape of Earth? The sense of symmetry by Greeks
demands a spherical Earth located at the center of the sphere of heavens.
ASTRONOMICAL EVENTS KNOWN TO MEN BEFORE THE ADVENT OF TELESCOPES
Before the advent of telescopes, humans depended on their senses to grasp the universe.
Ancient Babylonian, Assyrian, and Egyptian knew the length of the year and Egyptians, adopted
a calendar based on 365 days a year. The Egyptians also kept track of the yearly cycle of the star
Sirius which corresponds to the flooding of Nile. Early Chinese civilizations kept track of the
comets, meteors, and dark spots of the Sun. Mayan civilization also developed a calendar based
on the movements of Venus. Meanwhile, the Polynesians utilized the stars for navigation.
Below are astronomical events before telescope was invented.
Diurnal Motion
In modern astronomy, diurnal motion is defined as the apparent daily motion of stars and
other celestial bodies across the sky due to Earth’s rotation. Man has observed the sun rising
from the east and set in the west. The Greek astronomers have described ‘fixed stars’ moving in
the sky at the same arrangement and speed as most of the stars are. Stars whose movements
deviate from what seems to be fixed stars were called ‘planetes’ which means ‘wandering stars’
in Greek. The seven wandering stars are the Sun, moon, Mercury, Venus, Mars, Jupiter, and
Saturn.
Annual Motion
Annual motion is the apparent yearly motion of stars and other celestial bodies across the
sky due to Earth’s revolution. Below are events under annual motion.
Zodiac and the Ecliptic
If we trace the path the sun takes in the celestial sphere as we see on Earth, we would
have traced the ecliptic. A band of thirteen constellations collectively called zodiac can be seen in
the ecliptic. Ancient civilizations have observed that these constellations changes through months
as constellations are visible at different times in a year. These constellations served to mark the
time for planting and used by astronomers to develop a chart called horoscope.
Equinoxes and Solstices
Equinoxes are the two days in a year in which the sun crosses the celestial equator
occurring near March 20 (vernal equinox) and near September 22 (autumnal equinox). Midway
between these two equinoxes is the solstices. Solstices are the two days in a year in which the
Sun is at the farthest declination (north or south) from the celestial equator. Ancient Greeks and
Early Chinese civilizations have recorded solstices by observing the declination of the sun for
several days before and after the solstice. The calculated half-way between the days with the
equal declination of the sun at noon would be the solstice. This method also applies for equinoxes.
Precession
Hipparchus in 150 BCE has discovered based on his observation that the north celestial
pole has changed during the period of a half - century. He noticed that the slow and continuous
change in the direction in which the sky is moving. We understand at present that precession is
the slow ‘wobbling’ of Earth’s axis of rotation due to the gravitational pull of the Moon and Sun.
Figure 3 illustrates the 26,000-year cycle of precession. About 5,000 years ago the north celestial
pole is located at the star Thuban. At present, the north celestial pole is located near the star
Polaris and will be located at the star Vega after 14,000 years.
Eclipse
Eclipses occur when either the Earth or moon cast a shadow into each other. A solar
eclipse occurs when the moon passes between the Earth and sun with the moon casting a shadow
on the Earth’s surface. A lunar eclipse occurs when the Earth is directly aligned between the sun
and moon with the Earth casting a shadow on the moon. Take note that a solar eclipse may occur
only during the new moon phase, while a lunar eclipse may occur only during the full moon phase.
MODELS OF THE UNIVERSE
Throughout the history of astronomy, models of the universe have been projected. The
table below describes the model of the universe.
Planets usually rise from east to west as we see in the celestial sphere. However, it was
observed by the ancient astronomers that the planets seem to move westward for several weeks
and move eastward again in the succeeding weeks. In our current situation, we can explain that
these retrograde motions were due to the difference in the period of revolution of the planets
around the sun as seen in figure 7a. With Earth being closer to the sun, it moves faster than the
planets farther from the Sun. Ptolemy in his time held the belief that the Earth does not revolve
and is the center of the universe. The epicycle was used to explain these retrograde motions.
Here, a planet revolves in an orbit called epicycle while the center of the epicycle revolves around
Earth. This path of revolution of the epicycle is called deferent.
TYCHO BRAHE AND JOHANNES KEPLER
Tycho Brahe, a Danish astronomer continuously and precisely recorded the position of the
sun, moon, and planets for over 20 years using instruments that are like giant protractors. He
noted based on his observations that the positions of the planets differ from those that were
published. However, he was not able to develop a better model than Ptolemy’s as he didn’t have
the ability to analyze his data. Years before his death, he hired Johannes Kepler as a research
assistant to aid in analyzing his data. Brahe was reluctant to provide such data to Kepler, but at
his death, the observational data was possessed by Kepler. Being knowledgeable in geometry,
Kepler was able to derive from Brahe’s data that the orbital path of Mars was elliptical contrary to
the previous investigators who were trying to fit the planetary paths in circles. Generalizing his
results, he was able to formulate the three laws of planetary motion:
1. Law of Ellipse: orbits of all the planets are elliptical with the Sun at one focus of the ellipse. An
ellipse is a somewhat flattened circle. It is a closed curve in which the sum of the distances from
any point on the ellipse to foci (two points inside) is constant.
2. Law of Equal Areas: a line joining a planet and the Sun sweeps out equal areas in space in
equal intervals of time. Thus, a planet moves fastest when it is nearest to the sun.
3. Law of Harmony: the square of a planet’s orbital period (years) is proportional to the cube of
the semimajor axis of its orbit (in astronomical units or AU) or 𝑃2 = 𝑎3. Thus, the larger the orbit’s
size, the longer it takes to orbit the sun.
Activity 1.2 How far and how many years?
Using the formula given for the Law of Harmony, find the number of years a planet takes
to orbit the Sun and its distance from the Sun (semi-major axis).
Ex. Pluto’s a3 = 64,000. Its distance from the Sun (a) is equal to 40 AU. Likewise, Pluto’s 𝑃2
64,000. Its orbital period (P) is equal to 252.98 years.
Planet
Square of planet’s
orbital years (𝑃2)
Orbital period (a)in
years
Distance from the
sun (P) in AU
0.058
0.378
Cube of the semimajor axis of the
planet’s orbit (a3)
in
astronomical
units (AU)
0.058
0.378
Mercury
Venus
(1)
(3)
(2)
(4)
Earth
Mars
Jupiter
Saturn
1.00
3.54
141
868
1.00
3.54
141
868
(5)
(7)
(9)
(11)
(6)
(8)
(10)
(12)
Identification
Identify the astronomical events being described in each item. Write your answer on a separate sheet of paper.
1. It is the daily motion of stars and other celestial bodies across the sky due to Earth’s rotation. 2. It is a model which deems Earth
as the center of the universe.
3. An event in which the sun passes the celestial equator.
4. Occurs when the moon passes between the Earth and sun with the moon casting a shadow on the Earth’s surface.
5. A model which deems all planets revolve around the sun.
6. Set of thirteen constellations seen along the Sun’s ecliptic path.
7. The astronomical event in which the sun passes the highest or lowest point from the celestial equator.
8. It is the wobbling of the Earth’s celestial north pole.
9. The apparent yearly motion of stars and other celestial bodies across the sky due to Earth’s revolution.
10. It occurs when the Earth is directly aligned between the sun and moon with the Earth casting a shadow on the moon.