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Measurement
English Units of Measure and Equivalents
The Metric System of Measurement
Prefix decimal equivalent exponential equivalent Pico 0.000000000001 10^{-12} Nano 0.000000001 10^{-9} Micro 0.000001 10^{-6} Milli 0.001 10^{-3} Centi 0.01 10^{-2} Deci 0.1 10^{-1} no prefix 1.0 10^{0} Deka 10.0 10^{1} Hecto 100.0 10^{2} Kilo 1000.0 10^{3} Mega 1,000,000. 10^{6} Giga 1,000,000,000. 10^{9}
Scientific NotationScientists developed a method to make very large and very small numbers more manageable using coefficients and exponents based on the powers of 10.
2,543,455,000 would be written 2.5^{ }x 10^{9} 2.5 is the coefficient and 10^{9} is the exponent or the power of 10.
Very small numbers would be written like this 0.00000000804 = 8.04 x 10^{-9}
Significant Figures
Dimensional AnalysisNo naked numbers.... don't forget units!!!
Convert 8.50 inches to cm
Molecular Weight
•Molecular weight is the sum of the weights of all the atoms
in a molecule.
•A mole (mol) is equal in number to the molecular weight
of a substance, but upscaled from daltons to
units of grams.
Use the periodic table to calculate to molecular weight of each atom, and then add the totals together to get the mass of the molecule. Your answer should always contain the proper units, g/mol. •One mole of sucrose weighs 342 g.
•C_{12}H_{22}O_{11
}
•12 x
12 g =
144 g/mol
•22 x ___ = ___
• 11 x
___ = ___
342 g/mol
1.0 M solution would have 342 g of sucrose to 1
liter of water
One mole of ethyl alcohol (C_{2}H_{6}O) also contains 6.022 x 10^{23} molecules but weighs only 46g because the molecules are smaller. Calculating PercentTo find out what percent of one number is of another, divide the part by the whole.
What percent of 150 is 76? P x 150 = 76 So, 76 is about 51% of 150
When working word problems, use the following:
Graphing in Science
You are expected to graph in science to show your results. Make sure you understand the basics of graphing line graphs, lines of best fit, scatter plots, and spread sheets. You will need to know the difference between the independent variable and dependent variable and label your graph properly.
Graphs (i) The independent variable should be plotted on the x-axis (horizontal axis) and the dependent variable plotted on the y-axis (vertical axis). (ii) Each axis will be labeled with the physical quantity and the appropriate unit, e.g. time / s. (iii) The graph is the whole diagrammatic presentation. It may have one or several curves plotted on it. (iv) Curves and lines joining points on the graph should be referred to as 'curves'. (v) Points on the curve should be clearly marked as crosses (x) or encircled dots (o). If a further curve is included, vertical crosses (+) may be used to mark the points.
Pie Charts These should be drawn with the sectors in rank order, largest first, beginning at 'noon' and proceeding clockwise. Pie Charts should preferably contain no more than six sectors.
Bar Charts These are drawn when one of the variables is not numerical, e.g. percentage of vitamin C in different fruits (discontinuous). They should be made up of narrow blocks of equal width that do not touch.
Column Graphs These are drawn when plotting frequency graphs from discrete data, e.g. frequency of occurrence of leaves with different numbers of prickles or pods with different numbers of seeds. They should be made up of narrow blocks of equal width that do not touch.
Histograms These are drawn when plotting frequency graphs with continuous data, e.g., frequency of occurrence of leaves of different lengths. The blocks should be drawn in order of increasing or decreasing magnitude and they should be touching.
Lines of best fit A line of best fit (or "trend" line) is a straight line that best represents the data on a scatter plot.
This line may pass through some of the points, none of the points, or all of the
points. The "best-fit" line is the straight line which passes as near to as many of the points as possible using a ruler (a clear/transparent ruler is most helpful), keeping an equal amount of plots above and below the line . The best fit line does not have to originate at zero.
By drawing such a line, we are attempting to minimise the effects of random
errors in the measurements. http://www.youtube.com/watch?v=Ks7Q0dG_DEM&hd=1
Frequency Distribution This relative frequency of a particular observation or class interval is found by dividing the frequency (f) by the number of observations (n): that is, (f ÷ n). Thus: Relative frequency = frequency ÷ number of observations The percentage frequency is found by multiplying each relative frequency value by 100. Thus: Percentage frequency = relative frequency X 100 = f ÷ n X 100 Dependent and Independent VariablesDependent Variable (DV) A dependent variable is used synonymously with the term predictor variable. This variable is manipulated by the researcher, which in turn effects the independent variable.
Independent Variable (IV) An independent variable is also referred to as a criterion variable. This particular variable is measured, predicted and monitored. It is manipulated by the dependent variable in an experiment. As you explore the natural and physical world and begin investigating the cause and effect (correlations) between variables, it will become very clear there are common, frequently occurring mathematical relationships in science. There are also moderating variables, extraneous variables, control variables, and intervening variables.
Cooper, et al. (2006). In Business research methods (p. 41). New York: McGraw-Hill/Irwin.
TemperatureCommon temperatures to the nearest whole degree
*Remember, there is no such thing as negative in the Kelvin scale or °K, it's just K. Kelvin scale begins at absolute zero, (-273.15^{o}C). Absolute Zero is the coldest temperature, that means it's the temperature at which molecules (of any substance) have no more kinetic energy they can give up.
Converting Temperature Scales
•Celsius to Fahrenheit •F= (9/5 x C) + 32 •Fahrenheit to Celsius •C = 5/9(F-32) •Celsius to Kelvin •K = C+ 273
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Last modified: June 16, 2013 |