Planning Investigations (VCE SSCE Chemistry): Revision Notes

Planning Investigations

Introduction

Planning and designing an investigation carefully before you begin helps you maintain a clear and focused approach throughout your work. This involves several key steps: choosing a topic, developing your research question and variables, ensuring safety, applying ethical principles, and evaluating your sources of information.

Choosing a topic

When selecting a topic for your investigation, consider the following questions:

• Personal interest: Do you find the research topic interesting? Your engagement with the topic will help sustain your motivation throughout the investigation.
• Background information: Is there background information on your topic that relates to your VCE Chemistry course? This helps ensure your investigation is relevant and allows you to build on existing knowledge.
• Available resources: Does your school laboratory have the resources needed to perform the investigation? Consider equipment, chemicals, time, and access to facilities.
• Measurable data: Can you collect clear, measurable data? Your investigation should produce quantitative results that can be analyzed.

Potential research areas

Several practical research areas are suitable for VCE Chemistry investigations:

Production of energy	Production of chemicals
Efficiency of galvanic cells	Changes that can be made to electrolytic cells
Factors affecting the operation of fuel cells	Factors affecting the oxidation of ethanol to make ethanoic acid

Developing and refining your investigation

Conducting a literature search

Once you have chosen a topic, the first step is to conduct a search of the relevant literature. This means reading scientific reports and articles on the topic to find out:

• What is already known about the topic
• What is not known or not yet agreed upon
• Ideas for experimental methods

This background research provides important information for your report's introduction and helps you develop potential research questions.

Determining your research question

Your research question must be focused on ideas that are within your abilities to investigate, considering the resources and equipment you have available.

When developing your research question, consider:

• Equipment access: Do you have access to appropriate equipment such as waterbaths or data loggers?
• Time allocation: Do you have time to conduct the experiments? How many classes have been allocated?
• Location: Where will you conduct your research (e.g. in the school chemistry lab)?
• Variables: Can you identify the independent, dependent, and controlled variables?
• Hypothesis: Can you construct a hypothesis from your research question?
• Personal interest: Does the question interest you?
• Question format: Does the question end in a question mark? If it doesn't, it is not a question!

Format for controlled experiments:

In a controlled experiment, the research question should refer to the relationship between the independent variable and dependent variable. A useful format is:

"How does [the independent variable] affect [the dependent variable]?"

Defining your variables

Variables are the factors that change during your experiment. An experiment determines the relationship between variables.

There are three categories of variable:

• Independent variable: The variable that is controlled by the researcher. This is what you deliberately change in your experiment.
• Dependent variable: The variable that may change in response to a change in the independent variable. This is what you measure or observe.
• Controlled variables: All the variables that must be kept constant during the investigation. These ensure that any change in the dependent variable is due only to the change in the independent variable.

Examples of research questions and variables

Research question	Independent variable	Dependent variable
How does the surface area of the electrodes affect the current transferred through a galvanic cell made up of a $\text{Cu(s)}/\text{Cu}^{2+}\text{(aq)}$ and a $\text{Zn(s)}/\text{Zn}^{2+}\text{(aq)}$ half-cell?	Surface area of the electrodes—this could be varied by keeping a constant length and changing the width of the electrodes or keeping the size of the electrode constant and dipping a larger depth of the electrode into the half-cells for each variation	Current going through a simple circuit made up of the galvanic cell and an ammeter
How does the number of carbon atoms in alcohol affect the enthalpy of combustion of the alcohol?	Number of carbon atoms in the alcohol that is combusted	Enthalpy of combustion as determined using simple calorimetry
How does the vegetable oil from which biodiesel is synthesised affect the enthalpy of combustion of the biodiesel?	The type of vegetable oil (such as peanut oil, sunflower oil, sesame oil, etc.) used in the synthesis of biodiesel samples	Enthalpy of combustion as determined using simple calorimetry

Determining the aim

The aim is a statement describing in detail what will be investigated. It should be specific and clearly state the purpose of your investigation.

Making predictions and constructing a hypothesis

A hypothesis is a prediction based on scientific reasoning that can be tested experimentally. It defines a proposed relationship between two variables and takes the form of cause and effect.

Structure of a hypothesis:

A good hypothesis typically follows this format:

"If [change in independent variable], then [predicted change in dependent variable] because [scientific reasoning]."

Testing hypotheses:

Carefully designed experiments are conducted to determine whether the predictions made in a hypothesis are accurate:

• If the results of an experiment do not fall within an acceptable range, the hypothesis is rejected
• If the predictions are found to be accurate, the hypothesis is supported
• If, after many different experiments, one hypothesis is supported by all the results obtained so far and is considered verified using the scientific method, then this explanation can be given the status of a theory or principle

Selecting an appropriate methodology and method

When planning a scientific investigation, you need to think about the best way to address the research question. The scientific investigation methodology and the method (also known as procedure) selected will depend on the aim of the investigation and the research question.

Factors to consider:

• Do you have access to a laboratory, materials and chemicals (for a controlled experiment or product/process/system development)?
• Do you have access to a school or public library (for a literature review or case study)?
• Do you have computer access (e.g. international databases for classification and identification or for access to simulations)?

The method is the set of specific steps that are taken to collect data during the investigation.

Linking the planning parts together

Your research question, hypothesis, aim and variables should all link together coherently. Here is a complete example:

Component	Details
Research question	How does the number of carbon atoms in an alcohol affect the enthalpy of combustion of the alcohol?
Independent variable	The number of carbon atoms in the alcohol that is combusted
Dependent variable	The enthalpy of combustion as determined using simple calorimetry
Controlled variables	The spirit burner used to burn the hydrocarbon, the distance between the flame and the calorimetry can, the calorimetry can used to hold the water that is heated, the initial mass of alcohol in the spirit burner (affects how well the wick is soaked), the initial temperature of the water in the calorimetry can
Potential hypothesis	As the number of carbon atoms increases, the enthalpy of combustion will increase because there are more carbon-carbon bonds to break and more products ($\text{CO}_2$ and $\text{H}_2\text{O}$) are formed, so $\Delta H_{\text{products}} - \Delta H_{\text{reactants}}$ will increase.
Aim	To determine how the number of carbon atoms in an alcohol affects the enthalpy of combustion of the alcohol.

Modifying an existing investigation

When designing a research question for a controlled experiment, it is often easiest to modify an investigation that you have already conducted in class. You could use an existing method and choose a different independent variable (which might change the dependent variable).

Examples of modifications

Existing practical investigation	Potential student experiment
Synthesis of biodiesel	How does the vegetable oil from which biodiesel is synthesised affect the enthalpy of combustion of the biodiesel?
Half-cells and the electrochemical series	How does the concentration of the solutions in the half-cells affect the voltage of the electrochemical cell?
Preparing artificial fragrances and flavours	How does the number of carbon atoms in an ester molecule affect the boiling point of the ester?

Complying with safety guidelines

Everything we do involves some risk. A risk assessment is performed for a controlled experiment to identify, assess and control hazards. Always identify the risks and control them to keep everyone safe.

Identifying risks

To identify risks, think about:

• The activity you will be carrying out
• The equipment or chemicals you will be using or producing

Occupational health and safety

Occupational health and safety refers to all the measures that employers need to provide to ensure their employees are safe at work. Schools must also ensure that equipment and processes used in school laboratories are safe for all students, teachers and technical staff.

Chemical codes

The chemicals at school or at the hardware store have warning symbols on their labels. These symbols are a chemical code indicating the nature of the contents. From 1 January 2017, the Globally Harmonised System of Classification and Labelling of Chemicals (GHS) pictograms were introduced into Australia.

GHS pictograms and their meanings:

Pictogram	Use
Flame	Flammable liquids, solids and gases; including self-heating and self-igniting substances
Flame over circle	Oxidising liquids, solids and gases, may cause or intensify fire
Exploding bomb	Explosion, blast or projection hazard
Corrosion	Corrosive chemicals; may cause severe skin and eye damage and may be corrosive to metals
Gas cylinder	Gases under pressure
Skull and crossbones	Fatal or toxic if swallowed, inhaled or in contact with skin
Exclamation mark	Low level toxicity; this includes respiratory, skin and eye irritation, skin sensitisers and chemicals harmful if swallowed, inhaled or in contact with skin
Environment	Hazardous to aquatic life and the environment
Health hazard	Chronic health hazards; this includes aspiratory and respiratory hazards, carcinogenicity, mutagenicity and reproductive toxicity

Safety data sheets (SDS)

Each chemical substance has an accompanying document called a safety data sheet (SDS). An SDS contains important safety and first aid information about each chemical you commonly use in the laboratory.

Key information in an SDS:

• Product identification
• Hazard classification
• First aid measures
• Handling and storage
• Exposure controls and personal protection
• Physical and chemical properties
• Disposal considerations

Protective equipment

Everyone who works in a laboratory should wear items that help keep them safe. This is called personal protective equipment (PPE) and includes:

• Safety glasses
• Closed-toed shoes
• Disposable gloves for handling chemicals
• An apron or a lab coat if there is risk of damage to clothes
• A fume cupboard that should be used when toxic or corrosive gases are being handled or produced

Applying ethical principles

Ethics are a set of moral principles by which your actions can be judged as right or wrong. Every society or group of people has its own principles or rules of conduct.

Applying ethical principles in chemistry means:

• Using integrity and honesty when recording and reporting the outcomes of your investigation and when using other people's data (such as in a literature review)
• Recognising the importance of social, economic and political values when forming conclusions using scientific understanding
• Acknowledging the work of others by including in-text citations and details in a list of references

Green chemistry

Green chemistry is an approach to chemistry that aims to design products and processes that efficiently use renewable raw materials, and minimise hazardous effects on human health and the environment.

The 12 principles of green chemistry (most relevant to VCE Chemistry):

Principle	Description
Waste prevention	It is better to prevent waste than to treat it or clean it up after it has been produced.
Atom economy	Chemical processes should be designed to maximise incorporation of all reactant materials used in the process into the final product.
Less hazardous chemical syntheses	Wherever practicable, synthetic methods should be designed to use and generate substances that possess little or no toxicity to human health and the environment.
Designing safer chemicals	Chemical products should be designed to achieve their intended function while minimising toxicity.
Design for energy efficiency	Chemical processes should be designed for maximum energy efficiency and with minimal negative environmental and economic impacts.
Use of renewable feedstocks	Raw materials or feedstocks should be made from renewable (mainly plant-based) materials, rather than from fossil fuels whenever practicable.
Catalysis	Catalysts should be selected to generate the same desired product(s) with less waste and using less energy and reagents in chemical reactions.
Design for degradation	Chemical products should be designed so that at the end of their use they break down into harmless degradation products and do not persist in the environment.

Sourcing information

When you are sourcing information during your search of the literature, such as when researching experimental methods or investigating a broader issue, consider whether that information is from primary or secondary sources.

Primary and secondary sources

Primary sources of information are created by a person directly involved in an investigation.

Secondary sources of information include textbooks, newspaper articles and websites that present a synthesis, review or interpretation of primary sources.

All sources of information may have a bias (a focus on only one part or one direction of the data or evidence) so you need to determine if they are reliable sources of information.

	Characteristics	Examples
Primary sources	- First-hand records of events or experiences - Written at the time the event happened - Original documents	- Results of experiments - Scientific journal or magazine articles - Reports of scientific discoveries - Photographs, specimens, maps and artefacts - Interviews with experts - Websites (if they meet the criteria above)
Secondary sources	- Interpretations of primary sources - Written by people who did not see or experience the event - Use information from original documents but rework it	- Textbooks - Biographies - Newspaper articles - Magazine articles - Radio and television documentaries - Websites that interpret the scientific work of others - Podcasts

Using books and the internet

Peer-reviewed scientific journals are the best sources of information, but you are unlikely to have access to many of these, and much of the information is difficult to interpret if you are not an expert in the field.

Books and internet searches will most likely be your most commonly used resources for information.

Comparison of book and internet resources:

	Book resources	Internet resources
Advantages	- Written by experts - Authoritative information - Reviewed to ensure information is accurate - Logical, organised layout - Content is relevant to the topic - Contain a table of contents and index to help you find relevant information	- Quick and easy to access - Allow access to hard-to-find information - Allow access to a vast amount of information from around the world - Up-to-date information - May be interactive and use animations to enhance understanding
Disadvantages	- May not have been published recently - Usable by only a finite number of people at a time	- Time-consuming looking for relevant information - Search engines may not display the most useful sites - Cannot always tell how up-to-date information is - Difficult to tell if information is accurate - Hard to tell who has responsibility for authorship and if they are biased - Information may not be well ordered - Only a small proportion of sites are educational

Critically evaluating information

Not all sources of information are credible. Critical thinking involves asking questions when evaluating the content and its origin, including:

• Who created this message? What are the qualifications, expertise, reputation, and affiliation (who they work for or are associated with) of the author/s?
• Why was the information written?
• Where was the information published?
• When was the information published?
• How often has the information been referred to by other researchers?
• Are the conclusions supported by data or evidence?
• What is implied?
• What has been omitted?

Peer review

Peer review is a process in which other researchers who work in the same field review your work and provide feedback about your methodology and whether your conclusions are justified. Scientists are expected to publish their findings in peer-reviewed journals.

Examples of peer-reviewed chemistry journals include:

• Australian Journal of Chemistry
• Journal of the American Chemical Society
• Nature Chemistry
• Chemical Reviews
• Green Chemistry

Evaluating books and journals

Your textbook is an excellent starting point for reliable information. Information that you find elsewhere should be consistent with the information in your textbook.

Articles published in newspapers and magazines often present findings of new research, which may or may not be confirmed later, so be careful not to treat such sources of information as established fact. Peer-reviewed journal articles are likely to be up to date and reliable.

Evaluating websites

Remember that anyone can publish anything on the internet, so it is important to evaluate the credibility, currency and content of online information.

Website evaluation checklist:

• Credibility: Consider who the author is, their qualifications and expertise. Check for their contact information and for a trusted abbreviation in the web address, such as .gov or .edu. Websites using .com may have a bias towards selling a product (although this product could be a reputable science magazine or journal), and .org sites might have a bias towards one point of view (although these sites can be a good starting point for general information).
• Currency: Check the date the information you are using was last revised.
• Content: Consider whether the information presented is fact or opinion. Check for properly referenced sources, and compare information to other reputable sources, including books and science journals.

Recognising evidence compared to opinion and anecdote

An important aspect of the scientific method is to make conclusions based on data and evidence.

Data that is authoritative has been published by a credible source—for example, VCAA's VCE Chemistry Data Book.

Data should be objective (free of personal bias) and may be used as evidence, whereas opinion and anecdote are subjective (influenced by personal views). An anecdote is a story that might not be typical or representative of a pattern.

Data and evidence	Opinion and anecdote
Objective	Subjective
Measured, unbiased, replicable, systematic, representative	Personal, individual story, non-systematic, not necessarily representative or part of a pattern
Example: Scientific consensus among the majority of experts is that greenhouse gases are contributing to climate change.	Example: Today is a cold day, therefore global warming is not true.

Identifying information that is not scientifically valid

Beware of publications or sources of information that are presented as science but that are not scientifically valid. Non-scientific ideas and writing can be identified by:

• A lack of data or evidence
• Bias—only part of the data or evidence is considered (usually the data supporting the claim)
• Poorly collected data or evidence; for example, basing data or evidence on a group that is too small or not representative of the whole
• Invalid conclusions (that is, not supported by evidence)
• Lack of objectivity—appealing to emotion rather than presenting facts and evidence impartially