Ask a question Do background research Construct hypotheses Conduct experiments & collect data Analyse results & draw conclusions Hypothesis is true Hypothesis is false/partially true Think again Report Results Experimental Design – The Scientific Method
Constructing hypothesis A hypothesis is an educated guess about how things work. Hypothesis should be testable. In other words, you need to be able to measure both "what you do" and "what will happen."
Example of hypothesis Objectives To investigate if ethanolic and acetone extracts of leaves of dragon’s scale fern possess antibacterial activity against the Gram- positive Staphylococcus epidermis and Micrococcus luteus, and the Gram-negative Escherichia coli. Hypothesis Ethanolic and acetone extracts of leaves of dragon’s scale fern possess antibacterial activity against both Gram-positive and Gram-negative bacteria.
Experimental design Replications Rigour Controls Triplicates Fair test Experiments must test hypothesis Reproducible Experiments allow you to change some variables to test your hypothesis
Checklist What Makes a Good Experimental Procedure? For a Good Experimental Procedure, You Should Answer "Yes" to Every Question Have you included a description and size for all experimental and control groups? Yes / No Have you included a step-by-step list of all procedures?Yes / No Have you described how to the change independent variable and how to measure that change? Yes / No Have you explained how to measure the resulting change in the dependent variable or variables? Yes / No Have you explained how the controlled variables will be maintained at a constant value? Yes / No Have you specified how many times you intend to repeat the experiment (should be at least three times), and is that number of repetitions sufficient to give you reliable data? Yes / No The ultimate test: Can another individual duplicate the experiment based on the experimental procedure you have written? Yes / No
Searching for methods After idea is finalized, search for methods Google to find possible methods, discuss with mentor to check feasibility and whether the reagents/instruments needed are available. Be very clear what data you need to collect.
Garlic, an eco-friendly pesticide Theoretical background Research shows that the organo-sulfur compounds in garlic inhibit cancer. Garlic may be effective in killing insects.
Overview of method Measure the brain size of ants which are not fed with garlic (control) Feed ants with garlic extracts of different concentration Measure the brain size of ants fed with garlic extracts Compare initial and final readings, draw conclusions
Biodiesel as an alternative fuel Oil reserves are depleting very quickly Currently, oil has great economic, social and environmental influence Thus, an alternative fuel is needed. Biodiesel Renewable source of energy Biodegradable Produces less CO, SO 2 and unburnt hydrocarbon than diesel Does not contribute to a net rise in the amount of CO 2
Objectives To optimize the synthesis of biodiesel from waste vegetable oil. To compare the quality of biodiesel with that of commercial diesel
Reaction to produce biodiesel Transesterification
Methodology Collect waste vegetable oil (WVO) Reflux WVO with methanol and NaOH – vary the ratio of methanol to NaOH to optimize yield Separate and wash the product -biodiesel
Characterization of biodiesel using 1 H NMR @ NUS Waste vegetable oil Biodiesel
Further tests Biodiesel Cloud point test Test to measure energy content