Créer une présentation
Télécharger la présentation

Télécharger la présentation
## 2.1 Scientific Method

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -

**PreAP ChemistryChapter 2 NotesTurn Chapter 2 Annotation**Questions into the white box before you sit down.**2.1 Scientific Method**The Scientific Method is a logical approach to solving problems by observing and collecting data, formulating hypotheses, testing hypotheses, and formulating theories that are supported by data.**2.1 Scientific Method**There are two kinds of data that can be observed and collected: Qualitative and Quantitative.**2.1 Scientific Method**There are two kinds of data that can be observed and collected: Qualitative and Quantitative. •Qualitative data is data about qualities, like appearance and behavior.**2.1 Scientific Method**There are two kinds of data that can be observed and collected: Qualitative and Quantitative. •Qualitative data is data about qualities, like appearance and behavior. What qualitative data can be made about this apple?**2.1 Scientific Method**There are two kinds of data that can be observed and collected: Qualitative and Quantitative. •Qualitative data is data about qualities, like appearance and behavior. •Quantitative data is data about quantities, like mass, density, and other numerical amounts.**2.1 Scientific Method**There are two kinds of data that can be observed and collected: Qualitative and Quantitative. •Qualitative data is data about qualities, like appearance and behavior. •Quantitative data is data about quantities, like mass, density, and other numerical amounts. What quantitative data can be made about these apples?**2.1 Scientific Method**A hypothesis is based on previously collected data and is an attempt to explain the data, as a testable prediction; if A, then B. (It may not necessarily contain the words “if” and “then”). A hypothesis is tested with an experiment.**2.1 Scientific Method**A hypothesis is based on previously collected data and is an attempt to explain the data, as a testable prediction; if A, then B. (It may not necessarily contain the words “if” and “then”). A hypothesis is tested with an experiment. What if we ask: “Do different colors of light affect the growth of a green bean plant?” Is this a hypothesis? Is it testable? Is it a prediction?**2.1 Scientific Method**A hypothesis is based on previously collected data and is an attempt to explain the data, as a testable prediction; if A, then B. (It may not necessarily contain the words “if” and “then”). A hypothesis is tested with an experiment. What if we ask: “Do different colors of light affect the growth of a green bean plant?” Is this a hypothesis? Is it testable? Is it a prediction? How can this be phrased to be a prediction?**2.1 Scientific Method**In an experiment, usually the affect of one variable on another is tested. The variable that is being controlled directly by the experimenter is the independent variable. The independent variable should then have an affect on the variable being tested, called the dependent variable.**2.1 Scientific Method**In an experiment, usually the affect of one variable on another is tested. The variable that is being controlled directly by the experimenter is the independent variable. The independent variable should then have an affect on the variable being tested, called the dependent variable. What is the I.V.? What is the D.V.?**2.1 Scientific Method**Often there are additional variables that can be involved in an experiment, so care should be taken to be sure that these are held constant. In addition, to judge if the independent variable actually did affect the dependent variable and nothing else, a control situation should be used. This could be a separate specimen to which the independent variable is purposely held constant or is in the ‘usual’ state, or could be a separate trial of the same experiment, during which the independent variable is held constant or in the ‘usual’ state.**What needs to be constant?**What is the control?**2.1 Scientific Method**If a hypothesis is not disproved after many experiments to test it, then the hypothesis is considered a theory, like gravity or evolution.**2.1 Scientific Method**If a hypothesis is not disproved after many experiments to test it, then the hypothesis is considered a theory, like gravity or evolution. Sorry guys, they’re still just theories**40 rods = 1 furlong**1 furlong = 10 chains 1 chain = 66 feet**2 Mouthfuls = 1 Jigger**2 Jiggers = 1 Jack 2 Jacks = 1 Gill 2 Gills = 1 Cup 2 Cups = 1 Pint 2 Pints = 1 Quart`**2 Quarts = 1 Pottle**2 Pottles = 1 Gallon 2 Gallons = 1 Peck 2 Pecks = 1 Doublepeck**2 Doublepecks = 1 Bushel**2 Bushels = 1 Cask 2 Casks = 1 Barrel 2 Barrels = 1 Hogshead**40 Rods = 660 feet**1 Hogshead = 64 gallons**So:**40 Rods 1 Hogshead**10.3 feet**gallon**2.2 Units of Measurement**Horses are measured in hands. This used to literally mean how many hand widths to go down the side of the horse. For someone with small hands their horses will seem bigger than someone with big hands.**2.2 Units of Measurement**Horses are measured in hands. This used to literally mean how many hand widths to go down the side of the horse. For someone with small hands their horses will seem bigger than someone with big hands. To avoid these issues in science, scientists have adopted SI Units. (SI = Système International, French for International System.) These base units have been agreed on by the scientific community and will be used in this class.**2.2 Units of Measurement**Mass is a quantity of matter and is constant. Do not confuse it with weight! Astronauts on the moon have less weight, but not less mass (less mass would mean they were shrinking!) •1 kilogram is the same mass as 2.204622621849 pounds (but we'll use 2.20 lbs for this course)**2.2 Units of Measurement**Length is the distance between two points. •1 inch = 2.54 centimeters (exactly)**2.2 Units of Measurement**Temperature is the measurement of heat intensity (more about this later). •1 Kelvin is the same magnitude as 1 °C •0 ºC = 273.15 K**2.2 Units of Measurement**A mole is a count of something, like a dozen. By definition this is an exact count and not a measurement, but of course no one can count six hundred two sextillion two hundred fourteen quintillion one hundred and fifty quadrillion, so the number is determined mathematically. The best calculation is currently 602,214,150,000,000,000,000,000. Most often for this course the rounded off number below will be used. •1 mole = 6.022 × 1023 “particles” or things**2.2 Units of Measurement**The beauty of the SI units is that almost all of them can be scaled up or down by factors of ten with relative ease. Often once this is done a new prefix is added to base unit to indicate the new unit of measurement. You will need to understand and be able to use these prefixes for this course. Be sure to note which abbreviations use lowercase and uppercase letters! This distinction is very important. For example m and M are two different orders of magnitude.**Metric Prefixes**Larger than 1: Smaller than 1: prefixmeaningprefixmeaning yotta septillion deci tenth zetta sextillion centi hundredth exa quintillion milli thousandth peta quadrillion micro millionth tera trillion nano billionth giga billion pico trillionth mega million femto quadrillionth kilo thousand atto quintillionth hecto hundred zepto sextillionth deka ten yocto septillionth**2.2 Units of Measurement**Derived units are ‘new’ units that are made by combining two or more of the standard units together. Below are several derived units, how they are derived, and the usual SI units used with each. There are many, many more derived units.**2.2 Units of Measurement**Conversionfactors are a ratio derived from the equality between two different units that can be used to convert from one unit to the other. For example:**2.2 Units of Measurement**Conversion factors allow a quantity measured one way to be converted into a different way of measuring (although the overall amount should never change). Sometimes several conversion factors are used in the same calculation, but it is important to note that units in the numerator will cancel with identical units in the denominator. This process is called the factor label method or dimensionalanalysis**2.2 Units of Measurement**For example: How many quarters are in 6.53 dollars?**2.2 Units of Measurement**How many centimeters are in 2.34 miles?**2.2 Units of Measurement**How many centimeters are in 2.34 miles?**2.2 Units of Measurement**How many centimeters are in 2.34 miles?**2.2 Units of Measurement**How many centimeters are in 2.34 miles?**2.2 Units of Measurement**How many centimeters are in 2.34 miles?**2.2 Units of Measurement**How many centimeters are in 2.34 miles?**2.2 Units of Measurement**How many centimeters are in 2.34 miles?**2.2 Units of Measurement**How many centimeters are in 2.34 miles?