Senior Form Chemistry
– How do scientists do science?
How do scientists do science?
Student’s Version
Table of Contents
Activity 1: How do scientists tell other scientists what they are
doing?
P.1
Activity 2: Is vitamin C a cure for colds?
P.8
Activity 3: Are experiments the only way to develop scientific
knowledge?
Extension activity: Investigations about vitamin C
P.11
P.14
© 2007 The University of Hong Kong – Faculty of Education. All rights reserved
Senior Form Chemistry
– How do scientists do science?
Activity 1
How do scientists tell other scientists what they are
doing?
Hello! Oh, Sorry! I have got a cold! My mum just told me to take
some vitamin C to get rid of the ……..!!! I never heard of that!
Let me search for information concerning vitamin C. Hey! I have
found a famous person who believed vitamin C can cure colds.
Below are the notes I jotted down…
Linus Pauling
 He systematically developed our understanding about chemical bonding.
His work not only influenced modern research in chemistry but also
molecular biology.
 He was competing with Watson & Crick to discover DNA structure in
1950s.
 He is one of the few people who have been awarded two Nobel Prizes: one


in Chemistry (1954) and one for Peace (1962)
He believed that taking a high dose of vitamin C regularly could prevent
colds
He wrote a book Vitamin C and the Common Cold in 1970

Q1 Was Linus Pauling a chemist or a biologist?
Homework (Optional): Look for more information about Linus Pauling! Why was Pauling
given the Nobel Peace Prize in 1962? What does this tell you about the participation of
scientists in society?
P. 1
© 2007 The University of Hong Kong – Faculty of Education. All rights reserved
Senior Form Chemistry
– How do scientists do science?
Look at the cartoon showing the conversation between two scientists and discuss the
questions with your classmates.
I am finding if there is any
research about the effect of
vitamin C on the common
cold.
What are you doing?
S
Didn’t Linus
Pauling write a
book claiming that
vitamin C can treat
colds?
c
i
pa
pe
rs
e
Yes. But his claim is not
yet accepted by most
scientists.
Results must be reviewed by other
scientists. Oh! I’ve found them. There are
lots of studies investigating his idea.
n
cWhy?
e
Q1 Why do scientists have to spend time searching out and reading other scientists’ work?
Q2 Why have scientists conducted so many studies about the effects of vitamin C rather than
simply believing in what Pauling said?
P. 2
© 2007 The University of Hong Kong – Faculty of Education. All rights reserved
Senior Form Chemistry
– How do scientists do science?
As stated in the cartoon, scientists have to publish their
work in print or on the internet, in “scientific journals” to
let other scientists know about their results. There are
thousands of scientific journals in the world. You can find
some in the public libraries.
When a scientist submits a study to a particular journal the work will be
reviewed by the editorial board. The board is composed of a group of
scientists. They will review the quality of the papers and determine
whether the papers are good enough to be published.
The job of a reviewer (who is an expert in the field of the study) is to evaluate the quality
of a scientific paper. Factors such as (i) the significance and originality of the research (ii)
the validity of the investigation (iii) the trustworthiness of the results and findings (iv)
the quality of the writing and overall presentation will be considered. A significant piece
of research may open up new directions or areas for further investigation. A reviewer
will not repeat the research to check reliability. They will use their professional
knowledge to judge whether the paper is worthy of publication.
P. 3
© 2007 The University of Hong Kong – Faculty of Education. All rights reserved
Senior Form Chemistry
– How do scientists do science?
Let’s try the reviewing process! Divide into groups of four. Each of you will be a
reviewer of the Journal of Nutrition. Choose your role first!
Reviewer 1 (Dr. John Talaka)
You are Dr. John Talaka, a senior scientist at The China Nutrition Institute, also a reviewer for
the Journal of Nutrition. You have just received two papers from the chief editor. Every
journal has limited space. You have to decide which paper can be published in the journal.
You may also reject both papers.
Reviewer 2 (Dr. Louise Lee)
You are Dr. Louise Lee, a senior scientist at The University of Hong Kong, and a reviewer for
the Journal of Nutrition. You have just received two papers from the chief editor. Every
journal has limited space. You have to decide which paper can be published in the journal.
You may also reject both papers.
Reviewer 3 (Dr. Mary Wong)
You are Dr. Mary Wong, a senior scientist at Oxford University, also a reviewer for the
Journal of Nutrition. You have just received two papers from the chief editor. Every journal
has limited space. You have to decide which paper can be published in the journal. You may
also reject both papers.
Reviewer 4 (Dr. Kelvin King)
You are Dr. Kelvin King, a senior scientist at The University of Paris, also a reviewer for the
Journal of Nutrition. You have just received two papers from the chief editor. Every journal
has limited space. You have to decide which paper can be published in the journal. You may
also reject both papers.
After you have received the papers, you find that the study is very similar to the research that
you have been doing. You are also about to publish your results. If you allow the paper you
are reviewing to be published before yours, the impact of your study will become less
significant. In the science community, those who publish new finding will gain more credit.
P. 4
© 2007 The University of Hong Kong – Faculty of Education. All rights reserved
Senior Form Chemistry
– How do scientists do science?
Justify your decision in the following boxes.
Manuscript 1
Accept / reject (Please circle your decision)
Reasons:
Reviewers work independently.
Don’t discuss with each other
before you have made your own
decision.
Manuscript 2
Accept / reject (Please circle your decision)
Reasons:
Vote for the papers! Which paper did your group accept, or did your group reject both?
Now summarize the reasons for the group’s decision and present them to classmates.
P. 5
© 2007 The University of Hong Kong – Faculty of Education. All rights reserved
Senior Form Chemistry
– How do scientists do science?
Manuscript 1
Vitamin C is not destroyed by heat
Introduction
Vitamin C is believed to be lost during cooking. People always believed that we could not
take in enough vitamin C from cooked food. The purpose of the study is to investigate
whether heat can destroy vitamin C.
Materials and Methods
Vitamin C powder was purchased from ChemTech Ltd. A solution was prepared by dissolving
1 g of powder into 200 ml distilled water. 10 ml of vitamin C solution was kept at 20℃, 40℃,
60℃ , 80℃ or 100℃ for 30 minutes. The vitamin C content was then measured by titrating
the vitamin C solution against 1 ml DCPIP solution. The experiment was repeated until
consistent results were obtained.
Results and Discussion
Amount of vitamin C
used in titration / ml
The results are illustrated in the diagram below. There was no significant difference in
vitamin C content remaining after treatment at different temperatures.
3000
2500
2000
1500
1000
500
0
The graph shows the vitamin C
content of the solutions in different
temperature. The error bar shows
the standard deviation of each trial.
20
40
60
80
100
Temperature / o C
Summary
The results indicated that heat did not destroy vitamin C. Thus, food processing will not affect
the vitamin C content of a particular food.
P. 6
© 2007 The University of Hong Kong – Faculty of Education. All rights reserved
Senior Form Chemistry
– How do scientists do science?
Manuscript 2
Vitamin C Destruction during Heating
Introduction
Vitamin C is a vital substance for health. Heating is believed to destroy vitamin C thus
lowering the vitamin C content in food during cooking. The purpose of this experiment was to
determine whether increasing temperatures decompose Vitamin C.
Materials and Methods
Vitamin C solution was obtained by dissolving 1g of vitamin C in 500 ml distilled water
(vitamin C tablets were purchased from BioChem Technology Ltd.). For each temperature, 50
ml of vitamin C solution was used. The solutions were heated to 40℃, 60℃ 80℃ or 100℃
and maintained at a constant temperature for 15 minutes. A control solution was maintained at
room temperature (25℃).
After 15 minutes, vitamin C concentration was measured by titrating the vitamin C solution
against 1 ml DCPIP solution. The amount of vitamin C solution used was recorded. The
procedure was repeated three times at each temperature.
Amount of vitamin C used in
titration (ml)
Results and Discussion
The correlation between temperature and vitamin C concentration was determined using the
Statistical Analysis Computer Program version 1.0. There was no significant difference in
vitamin C content at different temperatures. The results are shown in fig.1.
0.3
0.25
0.2
0.15
Fig. 1. The graph shows the amount
of vitamin C used for the titrating
the DCPIP. The error bars show the
standard deviation in each trial.
0.1
0.05
0
25
40
60
80
100
o
Temperature ( C)
Summary
Vitamin C is not destroyed by heating. This is especially important for the food processing
industries. However, other factors such as oxidation and the decomposition of vitamin C in
different solutions (e.g. salt solution), which have not been considered in this study, may also
affect the availability of this micronutrient to consumers. Further study is needed.
P. 7
© 2007 The University of Hong Kong – Faculty of Education. All rights reserved
Senior Form Chemistry
– How do scientists do science?
Activity 2
Is vitamin C a cure for colds?
Unlike humans, most mammals are able to synthesize their own vitamin C. They are able to
produce vitamin C from glucose in the following steps:
W
X
Y
Z
Glucose Enzyme

 Chemical A Enzyme


 Chemical B Enzyme


 ChemicalC Enzyme


 Ascorbic Acid
Most of the above biochemical pathway also happens in our body. However, our body does
not have Enzyme Z. As a result, when glucose has been converted to chemical C, the reaction
stops and humans cannot synthesize vitamin C. We need it from our diet.
It has been found that when some animals are sick, the amount of
vitamin C in their body will increase tremendously. Therefore, Linus
Pauling suggested that the missing enzyme is due to a genetic
deficiency in our evolution and that when we are sick, we would, like
other mammals, need more vitamin C.
Pauling caused controversy about using vitamin C for treating or preventing disease. His
hypothesis is not easy to prove or disprove, but he has triggered extensive research on the use
of vitamin C for the treatment of colds. This famous experiment was conducted by Karlowski
and his colleagues in 1975. Details are on the next page:
P. 8
© 2007 The University of Hong Kong – Faculty of Education. All rights reserved
Senior Form Chemistry
– How do scientists do science?
Aims:
To determine whether taking vitamin C can prevent or cure colds.
Hypothesis:
1. Taking high doses of vitamin C helps prevent colds
2.
Taking high doses of vitamin C at the first signs of a cold reduces its length and
severity
Methods:
To investigate whether vitamin C can prevent colds, all subjects were asked either to take
the ‘maintenance capsules’ containing vitamin C or a placebo (安慰劑) daily (see table
below).This tests for hypothesis 1. Meanwhile, to test the second hypothesis, when they
felt the symptoms of a cold developing, they were asked to see the researchers and get a
supplementary capsule – which contained either vitamin C or the placebo – within 12
hours. When the cold was over, the subjects were asked to report the duration and severity
of the symptoms to the researchers.
311 subjects volunteered for the experiment. They were randomly assigned to four groups
as summarized in the table below. They did not know which group they belonged to.
Group
Maintenance capsule
Supplementary capsule
1
Placebo
Placebo
2
Placebo
3 g Vitamin C
3
3 g Vitamin C
Placebo
4
3 g Vitamin C
3 g Vitamin C
(N.B. A placebo is given to subjects in the control groups so that no subject can guess
whether or not they receive treatment. In this study, the placebos contained lactose.)
P. 9
© 2007 The University of Hong Kong – Faculty of Education. All rights reserved
Senior Form Chemistry
– How do scientists do science?
Q1 Can you find any problems in the experimental design? What are they?
Q2 If you were the researchers, what would you do when you discover the same problem?
Q3 After this study, scientists have continued to argue about the effect of vitamin C in curing
the common cold. Why? (Note: Pauling recommended 6 g to 18 g vitamin C daily.)
Q4 What can you observe about the attitude of scientists and the nature of science from this
study of vitamin C?
P. 10
© 2007 The University of Hong Kong – Faculty of Education. All rights reserved
Senior Form Chemistry
– How do scientists do science?
Activity 3
Are experiments essential in developing scientific
knowledge?
The study in Activity 2 is called an experiment. In your view, what is an experiment?
This is a brief summary of a piece of research reported in Japan in the year 2000.
The study was started in 1977 in a Japanese rural community. The researchers invited a
group of 880 men and 1241 women aged 40 years for investigation. These people were
followed by researchers for the subsequent 20 years. During the period, the researchers
recorded the number of strokes (中風) occurring in the sample. Meanwhile, the vitamin
C level in their blood and their diet were also recorded.
At the end of the study, there were 196 incidents of stroke. The number of strokes was
inversely related to the blood vitamin C level (i.e. the chance of getting a stroke was
lower in a person who had a high vitamin C level.)
Q1 Comment on whether or not this study is an experiment, give your reasons.
P. 11
© 2007 The University of Hong Kong – Faculty of Education. All rights reserved
Senior Form Chemistry
– How do scientists do science?
Q2 Suggest why the researchers use such approach for the investigation?
Experimental or non-experimental method, which one is better?
You are a group of scientists who are planning some medical
investigations. Decide whether you will use an experimental or
non-experimental approach. You have to prepare a 5-minute
presentation (i) to explain the aim of your study and (ii) to justify
your approach to the investigation.
Case 1
The harmful effects of passive smoking on foetuses have raised concern in recent years. You
and your colleagues want to know whether passive smoking may cause miscarriage (natural
abortion).
Is it possible to use an experimental approach in this case?
Case 2
A new drug has been produced for the treatment of HIV/AIDS. If the drug is effective, it
will save millions of lives. You have to investigate the effect of the new drug for treating
HIV/AIDS.
How can the effectiveness of the drug be determined?
P. 12
© 2007 The University of Hong Kong – Faculty of Education. All rights reserved
Senior Form Chemistry
– How do scientists do science?
Case 3
You suspect that a chemical present in a certain species of fish causes diarrhoea. If it is
really the case, there will be a dramatic decrease in cases of diarrhoea just by asking people
not to eat that species of fish.
How can you gather information to support your hypothesis?
After your presentation, summarize the benefits and drawbacks of different approaches in the
table below.
The pros and cons of using experimental and non-experimental approaches
Experimental approach
Non-experimental approach
Benefits
Drawbacks
Are experiments essential in developing scientific knowledge?
P. 13
© 2007 The University of Hong Kong – Faculty of Education. All rights reserved
Senior Form Chemistry
– How do scientists do science?
Extension activity: Investigations about vitamin C
Here are some typical images of science and scientists that people have.
(1) Science is done
in western
(4) Scientists work
in universities.
countries.
(2) Scientists work
alone.
(5) Science is done
only within a subject
discipline.
(3) Scientists are
male.
There are thousands of studies concerning various aspect of vitamin C. The next page
shows extracts of some real scientific papers about vitamin C. Find out whether the
images above are accurate or not. Do your observations of the papers agree with the
images of scientists /science suggested in the media?
P. 14
© 2007 The University of Hong Kong – Faculty of Education. All rights reserved
Senior Form Chemistry
– How do scientists do science?
1.
2.
P. 15
© 2007 The University of Hong Kong – Faculty of Education. All rights reserved
Senior Form Chemistry
– How do scientists do science?
3.
4.
5.
P. 16
© 2007 The University of Hong Kong – Faculty of Education. All rights reserved
Senior Form Chemistry
– How do scientists do science?
6.
7.
8.
P. 17
© 2007 The University of Hong Kong – Faculty of Education. All rights reserved