Chemistry
The Scientific Procedure
Chemistry is all around us. Did you know that everything is made out of chemicals? Any reaction taking place in body cells of all living and non living organisms correlates with chemistry. In chemistry we study materials that make up the earth and universe. Chemistry is sometimes called the central science because it bridges other natural sciences, including physics, geology and biology. Therefore, when talking about chemistry, we are referring to life on Earth.
The Scientific Procedure
Introduction
The scientific method refers to the processes that scientists use to conduct investigations or to find answers to the problems. It is a logical approach to problems solving by observing and collecting data, formulating hypothesis and formulating theories supported by data. These scientific methods provide standardized ways for scientists to conduct their works. In this chapter, you will learn about the significance of the scientific method, the main steps of the scientific method, and applications of the scientific method. By the end of this chapter, you should be able to describe each step of the scientific method and explain the importance of the scientific method. You are also expected to be able to use the scientific method to carry out investigations in chemistry
Significance of scientific procedure
The Concept of Scientific Procedure
Explain the concept of scientific procedure
The scientific method (procedure) is a process that scientists use to ask questions and conduct investigations to find answers to these problems. It is a logical approach to problem solving by observing and collecting data, formulating hypotheses, testing hypotheses, and formulating theories that are supported by data. The scientific method provides a standardized way for scientists to conduct their work. However, many scientists work according to other methods as well.
The Importance of the Scientific Procedure
Explain the importance of the scientific procedure
The scientific method refers to steps or guidelines followed when conducting investigations solving scientific problems. When we have a scientific problem, we carry out an experiment to solve it (Figure 4.1). The answers from the experiment can be applied in our daily life.
The main steps of the scientific procedure
The scientific method has the following basic steps:
- Problem identification.
- Hypothesis formulation.
- Experimentation.
- Data collection.
- Data analysis and interpretation.
- Conclusion.
- Reporting the results.
Each Step of the Scientific Procedure
Describe each step of the scientific procedure
Observation (identification) or statement of the problem
The first step of the scientific method is to identify a researchable problem and state it scientifically. For example, you may ask yourself whether surface area affects the rate of evaporation of water. The problem you want to investigate can be stated that, does surface area affect the rate of evaporation of water?
Hypothesis formulation
After identifying and stating the problem, you can formulate a testable hypothesis for that problem. A hypothesis is a tentative statement about the relationship between two or more variables. It is a guess or a possible answer to the question (problem). For example, for the above problem, you can formulate a testable hypothesis which states that surface area affects the rate of evaporation of water. This is just a statement. It can only be proved whether it is wrong or correct by setting up and doing an experiment.
Experimentation
After making a hypothesis, the next step is to plan and conduct an experiment. An experiment tests whether the hypothesis is true or false. Planning an experiment involves writing down steps for an experiment. An experiment should include short and clear steps. It should also include the materials and methods that will be used in the experiment. When conducting an experiment, it is important to note the factors that affect the problem you want to investigate. These factors are called variables. They can change or be changed during the experiment. Such factors may include temperature, volume, speed, light, concentration, and light.
There are three types of variables. These are:
- Dependent variable: This is the factor that changes its value when the values of the other variables change. It is the value being measured.
- Independent variable: This is the factor that is manipulated so as to obtain different values.
- Controlled (or constant) variable: This is the factor that does not change, or is kept constant all the time. It does not affect the result of the experiment.
In the experiment on evaporation of water; the rate of evaporation of water is the factor under investigation. This is the dependent variable. The surface area is the factor that is varied. This is the independent variable. The amount of water used is kept constant. This is the controlled or constant variable
To find out whether the surface area increases the rate of evaporation or not, we can design an experiment to prove or disprove the formulated hypothesis. The experiment is conducted by filling a basin (with the large surface area) and a beaker (with the small surface area) with 250 mL of water in each (Figure 4.2). Then the two containers are placed in the open air for the same duration of time. The containers used must be made of similar material, for example, plastic. Also, environmental conditions must the same. You should repeat your experiment several times to make sure that the first results were not just an accident
Observation and collection of data
This stage involves collecting and recording all the observations made during the experiment. Data is the information gathered during the experiment. Charts, graphs, lists, diagrams, tables, and even sketches can be used to record data during the experiment. Records appearing in the form of tables are easy to read, understand, and interpret. Tables are commonly used in collecting and organizing data during an experiment, and also for representing the data in a report. Tables are not suitable for showing a trend or relationship between variables. These are best represented by graphs.
Considering the experiment on the rate of evaporation, after a specific number of days, water from each container could be measured. The results obtained could be summarized as indicated in Table 4.1.
Data analysis and interpretation
After you have collected the data, you have to analyze and interpret it. This will enable you to make the correct conclusion. For example, in Table 4.1 you can see that 75 mL of water had evaporated from the basin as compared to 37.5 mL from the beaker. What do these data indicate? This means that from the basin (with the large surface area) water evaporated faster than that from the beaker (with the small surface area). The results reveal the fact that surface area plays a major role in evaporation of water and possibly many other liquid substances
Conclusion
This stage involves making inferences and drawing conclusion based on the formulated hypothesis. Scientists look at the information they gathered and observed. Then, they make connections to draw a conclusion. The conclusions may be or may not be in agreement with their predictions. Scientists may make incorrect predictions. An important part of the scientific process is to understand why predictions were incorrect. Many scientists will repeat an experiment several times to see if they can replicate the results before concluding
The data from the evaporation experiment show that higher amount of water (75 mL) was evaporated from the basin compared to the beaker (37.5 mL). The basin has a wider mouth and hence a large surface area than the beaker. From these results, of course, we can conclude that evaporation of water increases with an increase in surface area of the container in which that water is kept. Therefore, our hypothesis is proved true and correct. Remember always to base your conclusion on the collected and analyzed data, though it may deviate, to some extent, from the reality for one reason or another.
Reporting the results
The final step of the scientific method is to report the results. The findings may be communicated in the form of a written report or as an oral presentation. Scientists usually report their findings in scientific journals, where the reports are checked over and verified by other scientists
Application of the scientific procedure
The scientific procedure is used in many areas and in different fields of study. It is especially applied by scientists and researchers to find solutions to various scientific problems. Below are some of the areas where the scientific procedure is applied:
- In scientific research: Scientific research refers to a research conducted for the purpose of contributing towards science by the systematic collection, interpretation and evaluation of data in a planned manner. Researchers normally apply the scientific method when conducting researches on diverse scientific problems or phenomena. A researchable problem whose solution is sought for without following the correct sequence of the steps of the scientific method is not likely to get resolved
- In a field study: A field study (or field work) is often conducted to find answers to problems or test hypotheses. It involves doing some practical work that applies the scientific methods.
- When conducting experiments: An experiment is a methodical procedure carried out with the goal of verifying, falsifying, or establishing the accuracy of a hypothesis. Experiments vary greatly in their goals and scale, but always rely on repeatable procedure and logical analysis of the results.
- In project work: A project is a planned piece of work that involves careful study of a subject or problem over a period of time, so as to find information on the subject or problem.
The Scientific Procedure to Carry Out Investigations in Chemistry
Use the Scientific procedure to carry out investigations in chemistry
Activity 3
Aim: To find out if chalk dissolves in water
Materials: Beakers, tap water, pieces of chalk, mortar and pestle, sieve, crucible, stirring rod, source of heat, tripod stand, match box and sticks, tongs.
Procedure:
Note: Before you start, formulate a hypothesis for the experiment.
- Take four pieces of blackboard chalk and break them into halves.
- Put the broken pieces of chalk in a mortar and pestle.
- Use the pestle to grind the chalk into a fine powder. To obtain the finest powder, sieve the resulting powder with a sieve.
- Put the sieved chalk dust in a beaker.
- Add water to the chalk dust in a beaker until it is half-full.
- Stir the mixture vigorously for about 15 minutes.
- Let the mixture settle overnight. Observe whether the chalk dusts have dissolved in water.
Questions for discussion
- What hypothesis did you formulate?
- Could you see any particles of chalk after stirring?
- Could you still see any particles after settling?
- Is your hypothesis false or true?
- Draw a conclusion based on your findings.
Chapter summary
The scientific method is a set of organized steps followed to solve scientific problems.
The six steps of the scientific method are as follows:
- Problem identification;
- Hypothesis formulation;
- Experimentation;
- Data collection
- Data analysis and interpretation;
- Conclusion;
- Reporting the results
A hypothesis is a tentative statement about the relationship between two or more variables.
An experiment tests whether the hypothesis is true or false.
Factors that affect the problem under investigation are called variables. The basic three types of variables are: dependent variable, independent variable, and controlled (or constant) variable
Review questions
Question Time 4
A. 1. What is the second stage in the scientific method?
- Experimentation
- Hypothesis formulation
- Collection of data
- Data analysis and interpretation
2. Which of the following statements best describes the term hypothesis?
- A solution to a scientific problem
- A tentative explanation for a problem
- A doubtful conclusion
- A theory
3. The following are the ways of presenting data, except_______.
- charts
- graphs
- diagrams
- calculation
4. Which is the correct statement about the conclusion?
- It is based on the experimenter’s knowledge.
- It is based on the collected and analyzed data.
- It is a guessed solution to the problem.
- It is an accepted hypothesis.
5. Which one of the following are ways to present data?
- Essays, histograms, and pie charts
- Graphs, essays, and data analysis
- Graphs, histograms, and tables
- Observation, experimentation, and hypothesis
6. Write down the procedure you would use to prove or disprove the following facts:
- The weight of ash produced after burning wood is much less than the weight of wood.
- When sulphur is burnt in air, sulphur dioxide gas is produced.
- Chalk dusts do not dissolve in water.
- Sodium chloride is soluble in water.
- Sodium chloride absorbs water vapour from the air.
- A 100 cm3 sample of water weighs 100 grams.
- The air we exhale (breathe out) contains carbon dioxide.
B.Write TRUE for a correct statement or FALSE for an incorrect statement for each of the following statements:
- Every progress in science comes about through scientific discoveries.
- The scientific procedure is also called the scientific method.
- Observation does not involve making measurements and collecting data.
- It is not necessary for a hypothesis to be testable.
- Scientists base their conclusions on the collected data.
- The experiment should include short and clear steps.
- An experiment tests whether the conclusion is true or false.
- Observation and recording of data must be done only at the end of the experiment.
- Data analysis is based on the collected data.
- The conclusion does not necessarily depend on the collected data
C. Fill in the blanks
- _______is an organized set of steps used by scientists to carry out their investigations
- Experimenting involves________.
- The purpose of an experiment is _______.
- The ways of recording data during experiment include______.
5. What is the scientific method?
6. What is the scientific method?
7. Describe the purpose of the scientific method
8. Students conducted an experiment to find out the effects of fertilizer applications on maize harvest per hectare. Each bag of the fertilizer used weighed 25 kg and the bags of maize harvested weighed 100 kg each as shown in a table below.
| Bags of fertilizer | 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 | 90 | 100 |
| Bags of maize | 8 | 12 | 25 | 38 | 40 | 48 | 50 | 50 | 50 | 50 |
- Plot the results in a line graph. Insert the data of the bags of fertilizer on the x-axis and bags of maize on the y-axis
- What can you deduce about the influence of fertilizer on the growth of maize plants and hence the amount of harvests?
- What is the maximum limit of fertilizer to apply per hectare?
- Draw a conclusion based on the data presented in the table
9. Suppose you set up and conduct an experiment, but at the end you find that the hypothesis you formulated was wrong. What action would you take?
9. Outline the major activities in each of the steps of the scientific method
10. State the applications of the scientific method
REFERENCES
- Leeds, D., Payne, R. and McDuell, B. (Editor). (2001). Chemistry for OCR A. Bath Colour Books Limited. London.
- SCSU, MoEVT-Zanzibar. (2008). Chemistry for Zanzibar Secondary Schools, Forms 1 & 2. Oxford University Press. Dar es Salaam.
- Tanzania Institute of Education (1995). Secondary School Chemistry, Book One. NPC (KIUTA). Dar es Salaam.
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