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UNIT 1 Scientific research 1 Stages of the scientific method Scientific activity consists in discovering the laws that govern1 nature, a...

UNIT 1 Scientific research 1 Stages of the scientific method Scientific activity consists in discovering the laws that govern1 nature, a procedure we call the scientific method. govern: control, manage, be 1 responsible for. 1.  Observation and question. We ask questions about things we observe. solubility: ability to be dissolved. 2 For example, as you dissolve increasing amounts of sugar in water, you testable: able to be tested. 3 observe that there’s a time when the sugar no longer dissolves. Question: Does the amount of sugar you can add to water before it stops dissolving depend on the water temperature? Experiment 2.  Formulating a hypothesis. A hypothesis is an idea about what factors play a 1. Pour 100 ml of water into a role in the problem we’re investigating and what results we can expect. test tube and measure the For example, you formulate the hypothesis that if you increase the water temperature. temperature, the solubility2 of sugar in water increases. The hypothesis 2. Add 1 g of sugar to the tube must be testable3 through an experiment. and stir it. 3. Keep adding sugar, 1 g each time. Stir until the solution 3.  Testing and experimenting. For an experiment to be correct, it must be can’t dissolve any more carried out under controlled conditions, that is, all the factors affecting the sugar. experiment must be kept constant, except the one that you’re checking. 4. Repeat the experiment, This is called the independent variable. heating the water in the tube To check your hypothesis, you design an experiment (see left). to 30, 40, 50, 60 and 70 °C. The independent variable is the temperature of the water and is the only parameter you modify. Temperature °C Amount of sugar The dependent variable is the amount of sugar dissolved. You want to (g) dissolved in measure how it changes when you change the independent variable. 100 ml of water The control variables are other things that may affect the experiment. For 20 204 example, amount of water, type of sugar (white or brown) etc. 30 219 40 238 4.  Analysis of results and conclusions. Once we’ve taken measurements, we 50 260 organise them in tables and graphs to help us to visualise the results more 60 287 clearly and draw conclusions. See the results on the left. 70 320  The result of the experiment is that as the temperature rises, the solubility of sugar in water increases. Therefore, the hypothesis is correct. Solubility (g/100ml water) Sugar 5.  Laws or theories. From proven hypotheses, scientific laws are elaborated. A scientific theory may then be formulated to explain the laws. Scientific laws predict the value of the dependent variable for new independent variables not used in the experiment. Scientific theories try to explain why. Different theories may explain a scientific law and are considered valid until a new fact appears that disproves them. Notes 2 1. Scientific research 2 Representing data with tables and graphs plot: mark or draw points on a 1 The shape of the line that’s obtained when plotting1 the results on a graph graph. shows the correlation2 between the variables. correlation: relationship between 2 The independent variable is always plotted on the x-axis and the dependent two variables. variable on the y-axis. There are different types of correlation between rate: speed at which something 3 variables: happens. 1.  Directly proportional: A straight line passing through the origin of 4 intercept: point where a line on a coordinates indicates that the dependent variable increases at the graph crosses one of the axes. same rate3 as the independent variable. The equation that describes this variation is: y 5 a × x, where a is the gradient and the value that relates the two variables, also called the proportionality constant. If the straight line doesn’t pass through the origin of coordinates, the equation is: y 5 a × x + b, where a is the gradient and b the intercept4. In this case, the dependent variable minus the intercept (y – b) changes at the same rate as the independent variable. Straight lines 2. Inversely proportional: If the dependent variable decreases at the same rate as the independent variable increases, the graph is a hyperbola. The equation that represents this relationship is: y 5 k/x, where k is the proportionality constant. Hyperbola 3.  Proportional to the square: If the dependent variable changes at the same rate as the square of the independent variable, the graph is a parabola. The equation representing this relationship is: y 5 a × x2, where a is the proportionality constant. Parabola Notes 1. Scientific research 3  3 Quantities and units Measuring is comparing a quantity with a standard of measurement. For example, when we say that a certain length is 10 metres, we mean it has 10 property: characteristic of an 1 object, which we can measure. standard units of the established measurement for distances, the metre. arbitrarily: not based on any reason 2 A quantity is any property1 of an object that can be measured. A unit of or system. measurement is the standard by which we measure a quantity. uncertainty: something that’s not 3 We can measure many different properties of matter such as mass, length, known. volume and density. To do this, we need standard units of measurement and an appropriate instrument (for example a ruler). The International System of Units (SI) is based on seven fundamental or base quantities, which are abitrarily2 defined. Base quantities Unit of measurement Symbol Length metre m Mass kilogram kg Time second s Temperature kelvin K Amount of substance mole mol Electric current ampere A Luminous intensity candela cd Other quantities, called derived quantities, such as volume (V), acceleration (a) and force (F), are calculated from the base quantities. Callipers for measuring length In our daily lives, we use units that aren’t in SI units. For example, how do we convert 36 km/s into SI units? (1 km 5 1 000 m) 36km 1 000 m 1h 36 000 m × × = = 10 m/s 1h 1 km 3 600 s 3 600 s 36km 1 000 m 1h 36 000 m × × = = 10 m/s 1h 1 km 3 600 s 3 600 s There’s often error or uncertainty3 in the measurements we obtain in an experiment. Sometimes these errors are due to the measuring instrument. Digital balance for measuring mass Accuracy: How close a measurement is to the actual value. Precision: How consistent a measurement is, regardless of proximity to the actual value. Notes Sensitivity: The smallest absolute amount of change that can be detected by an instrument. The accuracy of an instrument is related to its sensitivity. For example, a thermometer with a precision of 1 °C won’t be able to detect tenths of a degree, so we can’t provide a measurement expressed in tenths of a degree with that thermometer. 4 1. Scientific research 3.1. Using measuring instruments Significant figures (also known as significant digits) of a number are digits that give us information about the precision of a measurement. round: increase or decrease a 1 Imagine that your measurement is between 7.6 and 7.7 cm but the number to the nearest significant precision of your ruler is 1 mm. This means that the significant digits of your figure. measurement are 7 and 6. If you used a ruler that had graduation marks in dismiss: remove something that is 2 centimetres you would only have one significant digit, which would be 7. not important. We round1 numbers to dismiss2 insignificant figures. For example, if we are using a ruler in millimetres, it won’t be precise enough to express a measurement as 7.6245 cm (with five significant digits). So, we round this number down to 7.62 cm. We round a number dismissing all the digits to the right of the last significant digit. The last significant digit is your rounding digit. Multiplying Rules for rounding prefix symbol factor Whole numbers: Identify the rounding digit. Look at the digit on the right. 1018 exa- E 1. If the digit on the right is 0, 1, 2, 3 or 4, don’t change the rounding digit. 10 15 peta- P All digits to the right of the rounding digit become 0. 1012 tera- T 2. If the digit is 5, 6, 7, 8 or 9, the rounding digit rounds up by one number. 109 giga- G All digits to the right of the rounding digit become 0. 10 6 mega- M Decimal numbers: Identify the rounding digit. Look at the digit on the right. 10 3 kilo- k 1. If the digit is 4, 3, 2 or 1, dismiss all digits to the right of it. 102 hecto- h 10 deca- da 2. If the digit is 6, 7, 8 or 9, add one to the rounding digit and dismiss all digits to the right of it. 10 –1 deci- d 3. If the digit is 5, add 1 to the rounding digit if it’s an odd number, but 10 –2 centi- c subtract one if it’s an even number or a zero, and dismiss all digits to 10–3 milli- m the right. 10–6 micro- μ Scientific notation allows us to write very large or very small quantities 10 –9 nano- n using powers of 10 with positive or negative exponents, depending on the 10–12 pico- p position of the zeros before or after the significant figure. 10–15 femto- f  The mass of the Earth is: 10–18 atto- a 6 000 000 000 000 000 000 000 000 kg 5 6.0 × 10 kg 24  The mass of an electron is: 0.000 000 000 000 000 000 000 000 000 000 910 9 kg 5 9.109 × 10–31 kg Notes 1. Scientific research 5  4 Working in a physics and chemistry laboratory A laboratory is specially equipped for experiments, research and other scientific or technical tasks. It must be equipped and arranged so that work flammable: easily set on fire. 1 can be carried out with the minimum risk of accident. clamp: device for holding things 2 firmly. Safety rules for working in the lab tilt: move something so that it’s 3 1. Find out where the emergency exits, fire extinguishers, eyewash and leaning or not vertical. emergency equipment are. 4 pipette: slender tube for 2. Don’t run inside the laboratory. transferring or measuring out small 3. Keep the work area clean and tidy. quantities of liquid in a laboratory. 4. Have only the books, notebooks and material you’re going to use on the table. 5. Wear gloves and a lab coat, always buttoned up. When necessary, wear safety glasses. Labelling of chemical products 6. Make sure your hands and clothes aren’t covered with residue of the Labels of commercial chemical substances you handle. Many can be toxic. products contain, along with the 7. Handle the glass instruments with great care so that they don’t break. list of some of their physical and 8. Don’t handle flammable1 substances near heat sources. To heat test tubes, chemical properties, information use a metal clamp2 and tilt3 it sideways. Don’t look inside the tube, or point about their nature that is its open end at anyone. indicated by symbols such as the ones shown here. 9. Don’t touch electrical appliances with wet hands. 10. Don’t store or consume food or drink in the laboratory. Wash your hands before leaving the area. 11. Strong acids and bases must be handled with care. They’re corrosive and, if they fall on your skin or clothing, can cause serious injuries and burns. 12. If you have to mix an acid (for example, sulphuric acid) with water, add the acid to the water, otherwise the acid will splash and could cause burns. 13. Always handle substances or reactions that release gas inside the fume cupboard. 14. Don’t pour waste down toilets. Use the special waste containers. Don’t return the remains of the substances that you haven’t used to the jars and containers – you might contaminate the stored substances. 15. Never suck up a reactant when using a pipette4. You could ingest a toxic and/or corrosive product. Use a pipette bulb. 16. Don’t leave bottles open or inhale their contents. Many liquid substances, such as alcohol, ether, chloroform and ammonia, release toxic gases. Notes 6 1. Scientific research 5 The structure of a scientific report Every research project that may be of interest to or have an impact1 on the impact: powerful effect. 1 scientific community is published as an article in a specialist journal and/or conference: large official meeting 2 presented at a scientific conference2. or event where people come In this section, you’ll learn how to write an article or report with the aims together to discuss their particular interest. and results of your work. The parts of a scientific report or a poster are usually: institution: organisation founded 3 for educational or professional Title: this should go in bold and in a larger font size than the rest of the text. purposes. Authors: name and surname (in a smaller font size) and institution3. Abstract: A summary of the article. The summary should contain the purpose and relevance of the research, the hypothesis that was tested, the method or experiments performed, the results obtained and the conclusions. Introduction: A brief description of your research. Explain why it may be of interest and its potential applications. It can also include a short historical summary that puts the research into context. Methods and measurements: A description of how the experiment was carried out and the measurements you used. Results: Present an analysis of your results using tables and graphs. Discussion and conclusions: Analyse the results you’ve obtained and draw conclusions from them. Explain the possible implications of your study and discuss what you’ve learned. References and bibliography: All the articles, books and other sources of information that you used in your research and have cited in the text must be listed. Notes 1. Scientific research 7  6 The impact of scientific research You use objects every day that wouldn’t have existed without scientific research and development. eradicate: get rid of something 1 completely. Science and technology work together for mutual benefit. Science contributes to technology with new knowledge that serves as a direct source of ideas for new technological possibilities. On the other hand, the development of new technologies contributes to science by providing the tools and techniques needed to address new and more difficult scientific questions. Here are some major technological developments that transformed our lives. Internal Steam engine Electricity Vaccines combustion engine This engine, Alessandro Volta These substances Various scientists developed in the discovered the generate and engineers 1800s, made use first practical immunity against contributed to of heat to drive method of specific diseases in the development a machine. This generating the body. They’ve of internal engine led to electricity, eradicated1 or combustion improvements in but it was the controlled most engines. They the transportation, discovery of serious infectious opened the door agriculture and electromagnetic diseases. to new means manufacturing induction that of transport, industries. revolutionised such as cars and energy usage. aeroplanes. Nowadays, we feel as if wouldn’t be able to live without mobile phones, the Internet or GPS, but these technologies didn’t exist 50 years ago. In the near future, artificial intelligence, machine learning and genetic engineering will also probably change the way we live. Can you think of other technologies that will change the world in the future? Notes 8 1. Scientific research