Methyl Orange - Department of Chemistry and Pharmaceutical

INDIVIDUAL STUDENT WORK BOOK
Methyl Orange
– online synthesis –
Chemistry Network
Department of Research and Theory in Education
VU University Amsterdam The Netherlands, 2012

Methyl orange
Name:
Mark:
Content
Explanation of the used icons:
Observation
Inquiry Question
Theory formation
Experiment
Execution
Conclusion
1. Introduction................................................................................................................................. 3
2. Experiment: methyl orange......................................................................................................... 5
3. Guide experiment: one molecule of methyl orange.................................................................... 7
4. Judging the inquiry of Haenen, Van Harmelen & Oortwijn....................................................... 9
5. Inquiry....................................................................................................................................... 17
6. First report and final article, teacher's feedback ....................................................................... 20
7. Study guide ............................................................................................................................... 22
8. List of concepts......................................................................................................................... 23
9. Some words explained.............................................................................................................. 24
Article Haenen, Van Harmelen & Oortwijn (2012) Synthesis of methyl orange in a micro reactor
2 Inquiry project

Methyl orange
1. Introduction
Nowadays chemistry forms an integral part of daily life. Whether it is clothes, food, body
care, cars, computers or drugs, everything people produce involves chemistry. Without
inventions and chemical research the world would be very different. Chemists conduct
research to acquire directly applicable knowledge, but sometimes also to understand
things better. Most of the time they build on research done by other chemists. Building on
knowledge of others can be advantageous because you do not need to examine things
yourself. On the other hand previous research causes problems of its own. When results
are not reliable, invalid conclusions may be drawn. Other research can be distorted by
invalid information and this may have serious consequences. That’s why accurate and
reliable research is important.
One of the aims of this inquiry project is to understand how to measure ‘fair’ and
accurate in your inquiry. This accuracy is necessary to get reliable results in your
inquiry. The only way to draw valid conclusions is to get reliable results.
Only when ‘fair’ and accurate measurements are taken, research results will be reliable
and valid conclusions can be drawn. Research should also be designed in such a way that
other researchers can repeat it. This does not mean, however, that knowledge based on
research results in itself is justified. Further investigations or other research can yield
results that are slightly different or even undermine acquired knowledge. Researchers
communicate about their research methods and their conclusions in professional
magazines, journals and on the Internet. Another way of informing the public and
politicians is by means of papers and television.
The student researchers Haenen, Van Harmelen & Oortwijn (2012 ) investigated the
influence of various flow rates on the formation of methyl orange in a micro reactor. How
‘fair’ and accurate is their inquiry? Do you think their inquiry results are trustworthy? Are
their conclusions valid? These are questions that you will answer by critically analysing
the article written by the three student researchers. Following this we expect you to
perform a better inquiry. You will write a first report on your inquiry and mail this to your
chemistry teacher. Your teacher will give you feed back on the quality of your report.
Weigh your teacher’s suggestions and use them to improve your report in changing it into
an article. Send your final article to your teacher for marking.
3 Inquiry project

Methyl orange
Below you find a time schedule for the inquiry project, ‘Methyl Orange’. All parts can be
done outside the chemistry lessons. Your first task is to become familiar with the inquiry.
Therefore you do a real and a guide experiment with methyl orange. After this you analyse
and evaluate an inquiry done by Haenen, Van Harmelen & Oortwijn (2012). Then you can
start with your own inquiry, write a first report and a final article.
Schedule for the procedure of the ‘Methyl Orange’ inquiry project (10-20 hours):
Procedure Part of the project
Start with the task 1. Understand aim and nature of the inquiry project
Conduct inquiry 3. Own inquiry
Write report 4. Report
2. Inquiry of Haenen, Van Harmelen & Oortwijn (2012)
• Predict, observe, explain
• Conduct guide experiment
Send first report 5. Report to: teacher
• Judge accuracy, reliability and validity
Feedback 6. Teacher will give feedback
Process comments 7. Processing the received comments, improve report
Send final article 8. Article to: teacher
Receive mark Teacher gives you a mark
4 Inquiry project

Methyl orange
2. Experiment: methyl orange
There are two Erlenmeyer flasks at hand. One contains household vinegar and the other
contains a soap solution. Add to each of the beakers a few drops of a methyl orange
solution.
2.1. Prediction
What do you expect to happen in each of the Erlenmeyer flasks?
I expect that
Why?
2.2. Write down your observations, conclusion and explanation.
Observations
Conclusion
Explanation
(i) Do you still agree with your expectations as written under “prediction” [2.1.]?
Yes / No, because
5 Inquiry project

Methyl orange
(ii) What causes the change in colour?
2.3. Browse the Internet for information on the synthesis of methyl orange and on the
use of methyl arrange as an indicator.
Write down your findings
6 Inquiry project

Methyl orange
3. Guide experiment: one molecule of methyl orange
In this modelling experiment you build one molecule of methyl orange.
3.1. Modelling experiment: building one molecule of methyl orange
(i) Use a model kit to build a model of one molecule of methyl orange.
The synthesis of methyl orange occurs in two steps:
Step 1: a nitrosonium-ion reacts with the amino group of the sulfanilic acid, attaching a
second N-atom at the sulfanilic acid to produce a diazonium salt, the diazotation process.
nitrosonium ion sulfanic acid diazonium salt water
Step 2: the diazonium salt is coupled with N,N-dimethylaniline, in which the coupling
takes place in the opposite position from the – N(CH3)2 group.
(ii) What is the diazotation process?
Methyl orange
7 Inquiry project

Methyl orange
3.2. Molecular formulas, molecular masses and calculation
(i) What are the molecular formulas and masses of sulfanilic acid and methyl orange.
(ii) Haenen, Van Harmelen & Oortwijn (2012) used 16.7 mmol of sulfanilic acid.
Calculate the maximum amount of methyl orange that theoretically can be produced.
(iii) What is your conclusion about this amount compared to the amount of methyl orange
that was found by Haenen et al. (2012)?
(iv) Explain your findings.
8 Inquiry project

Methyl orange
4. Judging the inquiry of Haenen, Van Harmelen & Oortwijn (2012)
‘Synthesis of methyl orange in a micro reactor’
Before analyzing the inquiry of Haenen et al. on ‘fairness’, accuracy, reliability and validity
you first answer some questions concerning accurate and reliable measurements.
4.1. Orientation on accurate and reliable measurements
Suppose that you would like to study the continuous flow of produced methyl orange in a
micro reactor. To detect the yield of methyl orange a spectrometer is used.
(i) Explain how this device works.
Assume that the recorded continuous flow of methyl orange is 0.50 mmol/L.
(ii) What would you do to find out if this measurement is reliable? Explain.
(iii) When is a series of measurements reliable? Explain.
4.2. Haenen, Van Harmelen & Oortwijn’s inquiry: accuracy, reliability, validity
The inquiry question of Haenen et al. (2009) was: ‘what are the ideal circumstances to
produce methyl orange?’
In paragraph 4.1 you have thought about reliability of measurements. In order to be capable
of measuring accurately, experiments need to be designed in a ‘fair’ way. You need
accurate measurements to come to reliable results. Only when results are reliable one can
draw the most valid conclusions. So the question is how to design your experiments as ‘fair’
as possible to measure most accurately.
To achieve accurate measurements researchers have to follow certain procedures. You will
practice this procedure using the article of Haenen et al. (2012):
How ‘fair’ is the design of the inquiry of Haenen et al.?
How accurate are the measurements of Haenen et al.?
How reliable are the measurements or results of Haenen et al.?
How valid is the conclusion drawn by Haenen et al.?
9 Inquiry project

Methyl orange
By practicing these steps you will be able to critically judge other research and be capable
of doing an accurate inquiry yourself.
A. How ‘fair’ is the design of the inquiry of Haenen et al. (2012)?
To judge a research design, you need to identify all of the variables that play a role in the
experiment. To take accurate measurements researchers want to know which variable they
will measure. Variables are quantities (e.g. temperature), which can be measured as a
number. Usually variables also have a unit (e.g. degree Celsius). Researchers should also
carefully take into account other factors (e.g. when measuring the height of a person the
floor on which the person stands should be straight), which can interfere with the variable to
be measured. When taking variables into account:
1 List all of the variables;
2 Choose one of the variables
3 Change this variable;
4 Measure the effect of this change; and at the same time
5 Keep all other variables and factors constant.
Researchers distinguish three types of variables:
Independent variable: This is the variable to be changed
Dependent variable: This is the variable to be measured
Control variables: These are the variables to be kept constant
By using distinct variables it is easier for researchers (and other interested people) to
understand the research and follow its progress. ‘Fair’ handling of variables is a difficult
aspect of research design. For researchers it is difficult both to recognize ‘all’ of the
variables and to exclude those variables and factors that they do not want to measure or to
change. In other words: to keep all interfering variables and factors constant.
Now it’s up to you to recognize the different variables in the experimental procedure of the
inquiry of Haenen et al. (2012) and to find out whether they handled the variables carefully.
10 Inquiry project

Methyl orange
B. Recognizing variables in the inquiry of Haenen et al. (2012)
Use the part on ‘Experimental procedure’ in the article of Haenen et al. (2012).
List all variables and factors that influence the measurements in the experiment as done by
Haenen et al. (2012).
(i) Variables:
(ii) Factors:
(iii) What is the independent variable in the experiment done by Haenen et al.?
(iv) What is the dependent variable in the experiment done by Haenen et al.?
(v) What are the control variables in the experiment done by Haenen et al.?
(vi) Did Haenen et al. (2012) forget any control variables?
If yes, which one(s)?
11 Inquiry project

Methyl orange
C. How accurately did Haenen et al. (2012) measure?
When the variables – related to the question under research – are known, the next step is to
think about the design and set-up of the experiments. It is important to decide carefully, in
advance how to conduct the actual experiment, both the set-up and the measurements.
Haenen et al. had to make decisions about:
i. The concentration and the inlet flow rate of solution A
ii. The concentration and the inlet flow rate of solution B
iii. The concentration and the inlet flow rate of solution C
iv. The temperature
With a well-developed research you will be less likely to encounter unpleasant surprises
while the experiment is being conducted.
To find out whether Haenen et al. (2012) did collect accurate measurements, you judge the
decisions made by them in their experimental procedure, see article of Haenen et al. (2012).
Discuss and answer the following questions:
C. 1. Decisions regarding the experimental set-up
(i) Did Haenen et al. choose a suitable temperature? Explain.
(ii) Did Haenen et al. choose suitable rate flows? Explain.
12 Inquiry project

Methyl orange
C.2. Decisions regarding the measurements
Did they read off the graph to a correct significant figure? Explain.
C.3. Decisions regarding the number of measurements
Haenen et al. conducted part of the experiments twice..
Was this enough times, according to you? Explain.
D. How reliable are the measurements or results of the inquiry of Haenen et al.?
Before collecting measurements researchers think about how to collect their observations
and data, how to present and analyze their results. Collected measurements are presented
in tables and graphs. Furthermore, researchers always need to check whether their results
are reliable. When measurements show too much deviation, they need to be repeated.
Repetition of measurements enhances the reliability.
You are now to judge whether Haenen et al. (2012) presented their measurements in a
correct manner and whether their measurements are reliable.
13 Inquiry project

Methyl orange
D.1. Presentation of measurements
Haenen et al. presented the flow speed and concentration in Table 1 as:
Table 1
Flow speed (µL/min) Concentration (M)
200, 400, 400 0,00031
800, 800, 400 0,00040
200, 400, 200 0,00064
200, 200, 400 0,00070
400, 200, 400 0,00076
400, 400, 400 0,00083
400, 200, 400 0,00111
200, 200, 200 0,00124
120, 75, 110 0,00154
400, 400, 200 0,00165
200, 200, 100 0,00397
100, 100, 50 0,00746
(i) Did they present the measurements in a correct manner? Explain.
Haenen et al. (2012) used a graph (see Figure 1) to “get the best of reality”.
Figure 1
(ii) Did they use the correct variables on the x-axis and y-axis? Explain.
14 Inquiry project

Methyl orange
(iii) Is the graph a good representation of the measurements as shown in Table 1? Explain.
D.2. Reliability of measurements
Haenen et al. (2012) did the part of the experiment twice. Suppose that regarding one flow
rate the measurements are allowed to deviate within 0.5% of the average result.
(i) Which of the results of Haenen et al. (2012) are accurate enough to be reliable?
(ii) What possible causes of inaccuracy in their measurements occurred:
(1) Temperature Yes / No Explain.
(2) Rate flow of solution A Yes / No Explain.
(3) Rate flow of solution B Yes / No Explain.
(4) Rate flow of solution C Yes / No Explain.
(5) Other causes. Yes / No Explain.
15 Inquiry project

Methyl orange
E. How valid is the conclusion of Haenen et al. (2012)?
A conclusion can be considered as valid when experiments are accurately designed and
carefully executed. Of course, experiments should be designed in such a way that
answering the research question is possible. Haenen et al.’s (2012) inquiry question was:
‘What are the ideal circumstances to produce methyl orange?’.
To answer this question they selected a temperature of 70 o C and various flow rates. The
results were presented in Figure 1 and Table 1. Out of these results Haenen et al. (2012)
concluded that the ratio of 2:2:1 creates the highest concentration of methyl orange.
(i) Do you agree with the conclusions Haenen et al. (2012)? Yes / No Explain.
(ii) Is the experimental design of Haenen et al. (2012) suitable or valid to find an answer
on the inquiry question as stated in their article? Yes / No. Explain.
16 Inquiry project

Methyl orange
5. Inquiry
The inquiry question of Haenen et al. (2012) was ‘What are the ideal circumstances to
produce methyl orange ?’ Out of their discussion a further question arise:
“So maybe another ratio would have created an even higher concentration of methyl
orange”
To answer this question, or your own question, you design and conduct your own inquiry.
You first need to write an inquiry plan in a ‘fair’, accurate, reliable and a step-by-step
manner and then you reserve time for the online experiment to conduct it.
It is all up to you! Before starting your own inquiry answer the part in 5.1.
5.1. Formulate your own inquiry question
An inquiry question can be investigated when this question has an independent (what are
you going to change?) and a dependent (what are you going to measure?) variable.
Write down:
(i) inquiry question:
(ii) hypothesis:
(iii) based on which theory:
Now write your own inquiry plan.
17 Inquiry project

Methyl orange
5.2. Inquiry plan
5.2.1 Variables
Dependent variable
What variable are you going to measure? Explain why.
Independent variable
What variable are you going to change? Explain why.
Control variables
Which variables and factors do you need to control - keep constant - in your experiment?
Explain why.
5.2.2. Decisions on the experiment, the experimental set-up and the measurements
How to make accurate measurements?
(i) Up to what significant figure can you read off the graph? Explain.
(ii) Are repeated measurements needed? Explain.
(iii) What reagents are used? List the materials.
(iv) What results do you expect? Explain why.
(viii) Check whether your inquiry plan is really answering your inquiry question.
If not, change your question into a question that fits to your plan.
Discuss your plan with your teacher. If she / he agrees, you can reserve time to
conduct the online experiments. See the manual.
Good luck!
18 Inquiry project

Methyl orange
5.3 Keep a record of the inquiry
Inquiry dairy
Date Work done Remarks / Observations
19 Inquiry project

Methyl orange
6. First report and final article, teacher’s feedback
This booklet needs to be handed in to your teacher. You will get a mark for your inquiry
plan and your final article.
6.1 Writing a report/article: guidelines
The layout of a report depends on the journal you are writing for. A report will be
published when it satisfies criteria posed by the journal. This will also be the case for your
article. After receiving your teacher’s comments on your report, you can use these
comments to improve your report as you write your final article.
Take the article of Haenen et al. (2012) as an example. Your report/article should contain
the following:
● Snappy but relevant title
● Names of the authors and submission date
● Summary of the inquiry
● Introduction with the reason of or problem in the inquiry guided by theory on the
problem, with the inquiry question and with a hypothesis and the theoretical
assumptions concerning the answer on the inquiry question.
● Experimental design with a description of the method of investigation, of the way
of handling the different variables and of the way of handling the accuracy in the
experimental set-up and the measuring itself.
● Results with a description of the relevant observations/ measurements that are
correctly put into tables and graphs.
● Discussion and conclusion with a critical interpretation of your results and with a
valid answer to your inquiry question.
● Evaluation with a critical description of the experimental set-up, with
suggestions for improvements and further inquiry questions.
● Bibliography with relevant resources like textbooks, websites, magazines,
articles.
Further guidelines:
• Use correct English and use a layout in 2 columns.
• Enclose a picture or drawing of the experimental set-up (max. 100 kb).
• The report/article should not exceed 1500 words (max. 500 kb).
• Label your document with your name.
20 Inquiry project

Methyl orange
6.2 Teacher’s feedback on the report
Ask your teacher to use the following feedback categories:
• Discuss whether the (in)dependent variables are visible in the inquiry question.
• Discuss whether the assumptions and theory about the hypothesis are relevant.
• Discuss whether the control variables are managed well.
• Discuss whether the measurements are accurate.
• Discuss whether the results are presented well.
• Discuss whether the reliability of the results are considered.
• Discuss whether you can approve of the discussion and conclusions.
• Discuss whether they wrote a critical evaluation.
• Discuss whether they came up with relevant bibliography.
Use the teacher’s feedback to improve your first article. Write a final article and
hand this in to your teacher.
21 Inquiry project

Methyl orange
7. Study guide
- Read the planning
Part 1. Understand what Haenen, Van Harmelen & Oortwijn (2012) investigated:
- Read the introduction
- Conduct the experiment with methyl orange: Predict, observe and explain
- Find information on the internet
- Read the article of Haenen, Van Harmelen & Oortwijn (2012)
Part 2. Evaluate the inquiry of Haenen, Van Harmelen & Oortwijn (2012):
- Conduct the guide experiment: one molecule of methyl orange
- Orientation on accurate and reliable measurements
- Read about variables
- Judge Haenen, Van Harmelen & Oortwijn’s article on handling variables
- Judge Haenen, Van Harmelen & Oortwijn’s article on accuracy
Part 3. Judge the accuracy and reliability in Haenen et al. ‘s inquiry:
- Judge the experimental set-up
- Judge the reliability of the measurements
- Judge the presentation of the results
- Judge the validity the conclusion
Part 4. Your own inquiry project: question and plan:
- Formulate an inquiry question
- Design an inquiry plan
- Hand in your inquiry plan to the teacher
- Reserve inquiry time for the conduction of the online experiments
Part 5-6. Your own inquiry project:
- Conduct your planned experiments and collect measurements
- Write a first report
- Send your first report to your teacher
- Ask your teacher to give feedback on the report
- Improve your report and write a final article
- Send your final article to your teacher
- Collect your mark on the inquiry project
22 Inquiry project

Methyl orange
8. List of concepts
Complete the list of concepts. Work gradually on this list as the project proceeds.
Write the definition of:
DIAZOTATION PROCESS
EXOTHERMIC REACTION
INDICATOR
INDEPENDENT VARIABLE
DEPENDENT VARIABLE
CONTROL VARIABLES
ACCURACY
RELIABILITY
VALIDITY
23 Inquiry project

Methyl orange
9. Some words explained
accuracy nauwkeurigheid
amount hoeveelheid
average gemiddelde
azo compound kleurstof
conditions omstandigheden
control variables controlevariabelen
dependent afhankelijk
dependent variable afhankelijke variabele
deviation afwijking
dye verstof
to increase toenemen
independent variable onafhankelijke variabele
inquiry onderzoek
opposite tegenovergesteld
to quence stoppen
reliable betrouwbaar
reliability betrouwbaarheid
set temperature ingestelde temperatuur
snappy pakkend
to submit insturen
validity geldigheid
24 Inquiry project