Prepared by
Mrs Yvonne Loi
1
The Chinese High School
Objectives
• To discuss what the science process skills
and attitudes important to the learning of
science are
• To state the laboratory safety rules and
recognise the various hazard symbols
• To state the names and functions of some
common laboratory apparatus (listed in
workbook)
• To draw, in proportion, sectional diagrams
of the apparatus
2
Objectives
• To dismantle the Bunsen burner and explain
how the various parts contribute to its
working
• To know the procedure of lighting a Bunsen
burner and able to light it correctly and with
confidence when doing practical work
• To obtain either a luminous or nonluminous flame by adjusting the size of the
air holes
3
Objectives
• To draw the diagram of a non-luminous
flame and label the various parts, i.e. dark
zone of unburnt gas, blue zone of partial
combustion, almost colourless zone of
complete combustion and hottest part of the
flame
• To explain the causes of the luminous and
non-luminous appearance of the flame
• To state which flame is more suitable for
heating and explain why
4
Objectives
• To carry out appropriate action during a
strike back
5
Do you know what science is all about?
The influence of science is all around us.
For example, a homemaker needs to know
science to cook well-balanced and nutritious
meals for his or her family.
6
Many devices that we used, such as the
telephone, cassette player and fluorescent
lamp, are based on scientific discoveries.
Fight against diseases such as AIDS
has been largely carried out by
scientific research.
7
Scientists are also making new discoveries to
solve global problems such as air and water
pollution. From such findings, they are able
to warn us about new hazards to our health so
that certain precautions can be taken.
Hazy weather
8
Science As An Inquiry
Science is the systematic
study of nature and how
it affects us and the
environment.
9
Branches of Science:
Biology
- The study of living things.
Chemistry - The study of substances and
how they interact.
Physics
- The study of matter, energy and
natural forces.
Astronomy - The study of the sun, the moon,
the stars, planets and other
heavenly bodies.
Geology - The study of structures of earth.
10
In the past, science was only described as a
body of knowledge. Later definitions of
science included the adoption of certain
methods or skills to discover and apply
scientific knowledge.
Today, the study and practice of science
involve three major elements
- attitudes
- processes or methods
- products
11
Attitudes
- Science encourages man to develop
positive attitudes.
The attitudes important to the learning of
science are
Curiosity
Perseverance
12
Positive approach to failure
Cooperation with others
Open-mindedness
Tolerance
13
Impartiality
Integrity
Healthy scepticism
14
Refusal to believe superstitions
Processes or methods
- Science process skills are used to develop
new processes or methods of
investigating and understanding science.
Science process skills refer to the different
types of skills including thinking and
reasoning skills, which are needed for
scientific investigation. They are broadly
divided into basic process skills and
integrated process skills.
15
The basic process skills are
To use our senses to
obtain information
about objects, events
and changes.
Observe?
To transmit and receive
information presented in
various forms - verbal,
written, tabulated,
graphical or pictorial.
Communicate?
To group objects or events
according to common
properties.
Classify?
16
To draw conclusions from
observations.
Infer?
To find out the physical
properties (e.g. length,
area and mass) of matter
accurately with the help of
measuring instruments.
Measure?
To make an educated
guess of how things may
turn out based on previous
experience or knowledge.
To approximate.
Predict?
Estimate?
17
Integrated process skills require pupils to
think at a higher level and to consider more
than one thought at a time. They combine
several of the basic process skills to form
better ways of solving problems.
Scientists have to carry out experiments to test
the hypotheses or to prove proposed concepts.
In carrying out the experiments, several
integrated process skills are required.
18
The integrated process skills are
- Observing carefully and measuring
accurately
This skill involves using our five senses,
sight, smell, hearing, taste and touch, to
gather information or make accurate
measurements about
a topic under study.
19
- Communicating effectively
This skill involves recording observations
or measurements in appropriate forms such
as tables, charts, graphs, labelled drawings,
formulae and other forms of
communication for easy reference.
20
- Making inference and developing a
hypothesis
An inference is a statement one arrives at
after much reasoning based on
observations or measurements. The making
of an inference involves thinking skills and
discussion with others to come up with the
best possible explanation for the
observations or measurements.
21
For an inference, scientists usually come
up with a hypothesis which is a suggested
explanation that can be tested through
experiments.
22
- Planning or designing experiments to
test the hypothesis
This skill involves deciding what apparatus
to use, how to put them together, what
observations to make or measurements to
take and how to do a fair test on the
validity of the hypothesis.
23
Science process skills will help you to
expand your scope of learning in science as
well as in other subjects through experience.
You begin with simple ideas which are
combined to form new and complex ideas.
All your ideas are valuable because they help
you to become a better decision maker,
consumer, problem solver, citizen and
member of our global society.
24
Products
- The information and ideas of science that
have been recorded as scientific
knowledge are called products.
Most scientists build on what other scientists
have discovered. This practice saves a lot of
time and energy. As new discoveries are made,
they are added to the scientific knowledge
base. Thus science has changed over time and
is subjected to further changes.
25
The understanding of the three major elements
of learning science is important to anyone who
studies and practises science.
26
Our innate experience often makes us curious
(attitudes) about phenomena occurring in
nature.
This curiosity about nature in turn motivates
us to develop new ways of processing ideas or
solving problems (processes or methods).
These lead to the construction of new
scientific knowledge (products).
27
28
Successful learning in science and other
subjects is the result of carrying out
continuous investigations relating to the
subjects.
This will enrich a person’s experience.
A learning cycle is thus formed and continues
to repeat itself as learning is a lifelong process
that never stops.
29
The Scientific Method
Different scientists may be carrying out
different scientific investigations but they all
share the common methods of investigation.
The scientific method is the most common
method used by scientists in their
investigations.
30
The Scientific Method - Investigative
The steps in the Scientific Method
- Observation
- Hypothesis
- Experiment
- Conclusion
To actually do a science experiment, many
more steps are needed. The following more
accurately reflects the course of an actual
experimental investigation.
31
- Initial observation.
-
You notice something, and wonder why it happens.
You see something and wonder what causes it.
You want to know how and why something works.
You ask questions about what you have observed.
(Write down what you have observed.)
Example:
Cooking instructions tell you to add salt to water
before boiling it.
32
- Information gathering.
-
Find out about what you want to investigate.
Read books, magazines or ask professionals who might
know in order to learn about the effect or area of study.
(Keep track of where you got your information.)
Example:
Cooking instructions tell you to add salt to water
before boiling it.
33
- Title the project.
-
Choose a title that describes the effect or thing you are
investigating.
The title should be short and summarize what the
investigation will deal with.
Example:
The Effect of Salt on the Boiling Point of Water.
34
- State the purpose of the project.
-
What do you want to find out?
Example:
To find out how salt affects the boiling point of
water.
35
- Identify variables.
-
Based on your gathered information, make an educated
guess about what types of things affect the system you
are working with.
(Identifying variables is necessary before you can make
a hypothesis.)
Example:
Variables - Amount of salt
Constant -
Amount of distilled water
The container to use
The place to perform the experiment
etc.
36
- Make HYPOTHESIS.
-
-
When you think you know what variables may be
involved, think about ways to change one at a time.
If you change more than one at a time, you will not know
what variable is causing your observation.
Sometimes variables are linked and work together to
cause something.
At first, try to choose variables that you think act
independently of each other.
At this point, you are ready to translate your questions
into hypothesis.
(A hypothesis is a question which has been reworded
into a form that can be tested by an experiment.)
37
-
-
-
Make a list of your answers to the questions you have.
This can be a list of statements describing how or why
you think the observed things work.
These questions must be framed in terms of the variables
you have identified.
There is usually one hypothesis for each question you
have.
You must do at least one experiment to test each
hypothesis.
(This is a very important step.)
Example:
Adding salt to boiling water will cause the water
38
to boil at a higher temperature.
- Design experiments to test your hypothesis.
-
-
Design an experiment to test each hypothesis.
Make a step-by-step list of what you will do to answer
your questions.
(This list is called an experimental procedure.)
For an experiment to give answers you can trust, it must
have a “control.”
(A control is an additional experimental trial or run. It
is a separate experiment, done exactly like the others.
The only difference is that no experimental variables
are changed.)
39
(A control is a neutral "reference point" for
comparison that allows you to see what changing a
variable does by comparing it to not changing
anything.)
(Dependable controls are sometimes very hard to
develop. They can be the hardest part of a project.)
(Without a control you cannot be sure that changing
the variable causes your observations.)
(A series of experiments that includes a control is called
a "controlled experiment.”)
40
-
Experiments are often done many times to guarantee that
what you observe is reproducible, or to obtain an average
result.
(Reproducibility is a crucial requirement. Without it
you cannot trust your results. Reproducible experiments
reduce the chance that you have made an experimental
error, or observed a random effect during one
particular experimental run.)
41
- Boil 200 cm3 of distilled water on a stove.
- Measure the temperature of the boiling water.
Record the highest temperature reading. This is
the control to compare with.
- Measure salt using a teaspoon. Level the
spoonful.
- Add the measured salt to the boiling water and
stir.
- Measure the temperature of the boiling water
with the salt in it. Record the highest
temperature reading. REPEAT.
42
Guidelines for experimental procedures.
- Select only one thing to change in each experiment.
(Things that can be changed are called variables.)
- Change something that will help you test your hypothesis.
- The procedure must tell how you will change this one thing.
- The procedure must explain how you will measure the
amount of change.
- Each type of experiment needs a "control" for comparison so
that you can see what the change actually did.
43
- Obtain materials and equipment.
-
-
Make a list of the things you need to do the experiments,
and prepare them.
Salt
Distilled Water
Beaker
Teaspoon
Thermometer
Stirrer
44
- Do the experiment and record data.
-
Experiments are often done in series.
A series of experiments can be done by changing one
variable a different amount each time.
A series of experiments is made up of separate
experimental “runs.”
During each run you make a measurement of how much
the variable affected the system under study.
For each run, a different amount of change in the variable
is used.
45
-
-
This produces a different amount of response in the
system. You measure this response, or record data, in a
table for this purpose. This is considered "raw data" since
it has not been processed or interpreted yet. When raw
data gets processed mathematically, for example, it
becomes results.
As you do experiments, record all numerical
measurements made. Data can be amounts of chemicals
used, how long something is, the time something took,
etc.
(If you are not making any measurements, you
probably are not doing an experimental science
project.)
46
Data Obtained: 2/25/95
Amount of boiling water
Temperature of boiling water (Control)
2 Cups
100.0°C
Amount of salt added to boiling water: Run 1
Temperature of boiling water after adding salt: Run 1
1 Tbl
101.0°C
Additional amount of salt added to boiling water: Run 2
Temperature of boiling water after adding salt: Run 2
1 Tbl
103.0°C
47
- Record your observations.
-
-
Observations can be written descriptions of what you
noticed during an experiment, or problems encountered.
(Keep careful notes of everything you do, and
everything that happens.)
Observations are valuable when drawing conclusions,
and useful for locating experimental errors.
48
- When the salt was added to boiling water it
bubbled up more, and then stopped boiling.
- Shortly afterwards, it boiled again.
- If the thermometer extends beyond the outside of
the beaker it reads a higher temperature.
- Heat from the Bunsen burner makes the
thermometer read higher.
- Keep the thermometer over the beaker when
making temperature measurements.
49
- Perform calculations.
-
Perform any calculations needed to turn raw data
recorded during experiments into numbers you will need
to make tables, graphs or draw conclusions.
Total amount of salt added for Run #1:
0 + 1 = 1 Teaspoon
Total amount of salt added for Run #2:
1 + 1 = 2 Teaspoons
50
- Summarize results.
-
-
-
-
Summarize what happened. This could be in the form of
a table of processed numerical data or graphs. It could
also be a written statement of what occurred during the
experiments.
It is from calculations using recorded data that tables
and graphs are made.
Studying tables and graphs, we can see trends that tell
us how different variables cause our observations.
Based on these trends, we can draw conclusions about
the system under study.
These conclusions help us confirm or deny our original
hypothesis.
51
-
-
Often, mathematical equations can be made from graphs.
These equations allow us to predict how a change will
affect the system without the need to do additional
experiments.
Advanced levels of experimental science rely heavily
on graphical and mathematical analysis of data.
52
Results.
Temperature of boiling water (Control)
100.0°C
Amount of table salt added to boiling water: Run #1
Temperature of boiling water after adding salt: Run #1
1 Tbl
101.0°C
Total amount of table salt added to boiling water: Run #2
Temperature of boiling water after adding salt: Run #2
2 Tbl
103.0°C
53
- Draw conclusions.
-
-
Using the trends in your experimental data and your
experimental observations, try to answer your original
questions.
Is your hypothesis correct?
Now is the time to pull together what happened, and
assess the experiments you did.
Is the hypothesis correct?
Yes. Adding salt to water causes the water to boil
at a higher temperature.
54
Other Things You Can Mention in the Conclusion.
- If your hypothesis is not correct, what could be the answer
to your question?
- Summarize any difficulties or problems you had doing the
experiment.
- Do you need to change the procedure and repeat your
experiment?
- What would you do different next time?
- List other things you learned.
55
- Problems with doing the experiments.
The temperature readings were hard to make.
Gloves had to be worn to keep my hands from
getting too hot.
Had to be careful that the heat from the Bunsen
burner was not hitting the thermometer.
- Other things learned.
Be careful when adding salt to boiling water. It
makes the water boil vigorously for a second or
two.
56
- Try to answer related questions.
-
-
What you have learned may allow you to answer other
questions.
Many questions are related.
Several new questions may have occurred to you while
doing experiments.
You may now be able to understand or verify things that
you discovered when gathering information for the
project.
Questions lead to more questions, which lead to
additional hypothesis that can be tested.
57
Why do you think cooking instructions tell you to
add salt when boiling water?
When the water is hotter, you can cook food
faster.
Salt also makes the food taste better.
58
- What if my science project doesn't work?
-
-
No matter what happens, you will learn something.
Science is not only about getting “the answer.”
Even if your experiments don't answer your questions,
they will provide ideas that can be used to design other
experiments.
Knowing that something didn't work, is actually knowing
quite a lot.
Unsuccessful experiments are an important step in
finding an answer.
Scientists who study extremely complex problems can
spend a lifetime and not find “the answer.”
Even so, their results are valuable.
Eventually, someone will use their work to find the
answer. Are you that person?
59
Example
Observation:
Record:
Shadows are cast when objects block light.
Hypothesis:
Light travels in a straight line.
60
Experiment:
61
Theory:
The hypothesis that light travels in a straight
line becomes a theory.
Law of science:
After being tested a number of times and
found to be true, the theory that light travels
in a straight line finally becomes a law of
science.
62
Safety Rules in the Laboratory
Science experiments are usually performed in
laboratories. Although performing experiments
is fun, it can be dangerous if we are not
careful. For our safety as well as the safety of
others in the laboratory, we must follow
laboratory safety rules.
63
General safety rules
- Do not enter the laboratory without the
teacher’s permission.
- Open all doors and windows unless
otherwise instructed by your teacher.
- Do not carry out any test or experiment
without the teacher’s permission.
- Read the instructions first and understand
them before starting any experiment. If in
doubt, always ask your teacher.
64
- Handle all apparatus and chemicals
carefully and correctly. Always check the
label on the container before using the
substance it contains.
- Do not pour any unused chemicals back into
its container to avoid contamination.
- Do not taste any chemicals unless otherwise
instructed by the teacher.
- Do not eat, drink or play in the laboratory.
- Do not tamper with the electrical mains and
other fittings in the laboratory.
65
- Work tidily. Wash up all used apparatus and
dispose of the waste correctly.
- Return the apparatus to their proper storage
places after cleaning.
- Do not remove any apparatus or chemicals
from the laboratory.
- Wash your hands after all laboratory work.
66
Safety rules when heating or mixing
chemicals
- Wear goggles when mixing or heating
chemicals.
- Place flammable substances away from a
naked flames.
- Point the mouth of a test tube or
boiling tube which is being heated away
from yourself or your friends.
67
When accidents occurs
- Report all accidents, injuries, breakage
and spillage to your teacher immediately.
- Should a chemical get into your mouth, spit
it out into a basin and rinse your mouth with
plenty of water.
- If any chemical comes into contact with
other parts of your body or clothing, wash
thoroughly with water and report to your
teacher.
68
Alice Playing in the laboratory Meng Tat
Susan
Sleeping in the laboratory
Ali
Hair may catch fire if not tied up
The chemicals in the pipette may enter the mouth
Mike
Tampering with faulty
electrical components
Shamala
Pointing the mouth of the test tube
which is being heated towards herself
Spillage of liquids on the bench
69
Containers of dangerous chemicals are
labelled with special symbols to warn others
about the hazardous nature of the chemicals.
Symbol
Type of
hazardous substances
Proper handling
Flammable substances
Example:
petrol, kerosene,
alcohol
Keep flammable
substances away from
fire or heat.
70
Explosive substances
Example:
mixture of hydrogen
and oxygen
Explosive substances
usually explode when
heated or lit. Use them
according to the
instructions given.
Corrosive substances
Example:
strong acid and alkali
Avoid direct contact
with the corrosive
substances which can
cause burns. Wash off
any spilled acid or alkali
on your skin or clothes
with plenty of water.
71
Poison or toxic
substances
Example:
mercury, cyanide,
chlorine gas
Do not eat, drink or taste
these poisonous
substances. Use them
according to the
instructions given.
Irritating or stimulative
substances
Example:
chloroform, alcohol,
bromine vapour
Avoid inhaling the
vapour of stimulative
substances. Use them in
a fume chamber.
72
Radioactive substances
Example:
radioactive carbon,
uranium, plutonium
Strictly adhere to all
safety precautions when
handling radioactive
substances.
This danger sign warns you to be
careful.
!
When smelling unknown gases,
fan a small part of the gas towards
your nose.
73
Laboratory Equipment
There are many types of apparatus, especially
glassware, in your school laboratory. Some
common laboratory items are test tubes,
beakers, conical flasks, measuring cylinders,
test tube holders, gas jars, balances, tripods
and retort stands.
You must know how to use these apparatus
and draw each of them in outline only and in
their correct proportions. (sectional diagram) 74
For containing or heating small
amount of substances
For containing or heating small
amount of liquids
75
For containing chemicals or collecting liquids
76
For containing chemicals when
preparing gases if the process
requires no heating
For preparation of gases if the
process requires heating
77
For measuring a volume of liquid
to an accuracy of 0.5 cm3
For measuring a volume of liquid
to an accuracy of 0.1 cm3
78
For measuring very accurately a
specific volume of liquid, such as
10 cm3, 25 cm3 and 50 cm3
For transferring liquids into a flask
79
For separating an insoluble solid
from a liquid with the help of a
piece of filter funnel
For displaced liquid to flow out
through its spout
80
For collecting gases
For separating an experimental
set-up from the outside environment
81
For evaporating a liquid from a
solution
For heating solids directly over a
flame
82
For containing water when
collecting gases
For supporting apparatus during
heating
83
For supporting apparatus during experiments
84
Distilling flask
Liebig Condenser
For containing the liquid mixture
which would distill the component
liquid when heated
To allow the distilled vapour to
condense in order to collect the liquid
85
Bunsen burner
86
Bunsen burner
87
Bunsen burner
Barrel: to raise the flame
to a suitable height for
burning
Air-holes: to allow air to
enter the burner
Jet: to enable the gas to
rush out of the gas
supply and to draw in
air
Collar: to regulate the amount of
air entering the burner through the
air-holes
Base: to support burner
so that it will not topple
Gas tap: to control the flow
of gas to the Bunsen burner
88
Lighting the Bunsen burner
1. Close the air-holes.
2. Strike a match and bring it to the top of
the barrel.
3. Turn on the gas tap with your free hand.
Types of flame
Luminous flame - Produced when the gas does not
burn completely
Non-Luminous flame - Produced when the gas burns
completely
Strike back - Produced when there is too much air
89
Luminous flame
- Occurs when the air-holes are closed,
insufficient air is allowed to mix with the
gas therefore gas does not burn completely.
- Carbon particles are produced.
- Orange in colour.
- Appear flickering and unsteady.
- Not very hot.
90
orange zone of incomplete combustion
almost colourless zone of
complete combustion
blue zone of partial combustion
dark zone of unburnt gas
Bunsen burner
91
Non-Luminous flame
- Occurs when the air-holes are opened,
allowing sufficient air into the burner
therefore gas is burn completely.
- Blue in colour.
- Burns steadily.
- Hotter than the luminous flame.
- Hottest part of the flame is just above
the tip of the dark blue zone.
92
almost colourless zone of
complete combustion
hottest part
blue zone of partial combustion
dark zone of unburnt gas
Bunsen burner
93
Strike Back
- Occurs when there is too much air.
- There is a large supply of air because the
air-holes are fully opened.
- Instead of burning at the mouth of the
barrel, the gas burns at
the jet.
- When a Strike Back
occurs, turned off
immediately.
- Very hot.
94
Heating a liquid in a beaker
- The beaker is placed on a tripod stand.
- A piece of wire gauze is placed between
the beaker and the tripod stand.
- The burner burner is then placed under
the tripod stand and lighted.
- The beaker is
removed from
the flame when
the liquid starts
to boil.
95
Heating a liquid in a test-tube
- The test-tube must be held with a test-tube
holder.
- Ensure that the mouth of the test-tube is
facing away from yourself or any other
person.
- Slant the test-tube
at an angle of
about 45O and heat
it with a Bunsen
flame.
96
- Move the test-tube in and out of the flame
occasionally.
- The liquid to be heated should occupy no
more than one-third the height of the testtube.
97
Benefits and Abuses of Science
and Technology
A lot of exciting discoveries and inventions
have been made using science an technology.
The way scientific
discoveries and
inventions are used
by people is called
technology.
Computer chips in silicon wafer98
Video conferencing, the Internet and cloning
of animals are all products of technology.
Communication using satellites
99
Benefits
Technology has greatly benefited us as it has
enabled us to grow more food, make our
homes more comfortable, communicate faster
over long distances,
move from place to
place with ease and
explore outer space.
Vegetables grown using hydroponic methods
100
The discovery of new medicines which can
prevent or cure diseases, and the invention of
machines which can used
in medical treatment
enable us to live longer
and healthier.
A patient with kidney failure receiving treatment
101
Benefits of Science and Technology
- Improve health
- Prolong lifespan
- Make lives more comfortable and
convenient
- Enable people all over the world to
communicate
- Reduce damage caused by natural disasters
102
Abuses
Unfortunately, scientific discoveries and
technology have at times been misused by
man.
For example, the invention
and use of deadly weapons
are harmful to us and the
environment.
A nuclear explosion103
The abuse of science and technology has also
resulted in different forms of pollution.
Factory chimney spewing
pollutants into the air
We must therefore use science and technology
with great care.
104
Abuses of Science and Technology
- Pollute the environment
- Destroy lives
- Deplete nature’s resources
- Upset the balance in nature
105
Limitations of Science
Although science has helped us in many ways,
it must be noted that it has its limitations.
Science cannot be used to find an answer to all
our questions or to solve all our problems.
For example, we can use science to reduce the
damages caused by natural disasters such as
earthquakes and hurricanes but we cannot
prevent them from happening.
106
Science cannot
- give life to non-living object.
- forecast future events.
- explain matters relating to religions.
- help us return to the past or go to the future.
107
References
Tho Lai Hong, Ho Peck Leng, Goh Ngoh Khang,
(2001), Interactive Science 1, Pan Pacific
Publications.
Chan Kim Fatt, Eric Y K Lam, Lam Peng Kwan, Loo
Poh Lim, (2000), Science Adventure, Federal
Publications.
Chuen Wee Hong, Lee Khee Boon, Hilda Tan, Ruth
Chellappah, Koh Thiam Seng, Yap Kueh Chin,
(2000), EPB.
108