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MSU / Chemistry / CHE 201 / What is the study of the composition, structure, properties, changes t

What is the study of the composition, structure, properties, changes t

What is the study of the composition, structure, properties, changes t

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School: Murray State University
Department: Chemistry
Course:
Professor: Wafaa fawzy
Term: Fall 2015
Tags:
Cost: 50
Description: 1 Chapter One Matter, Measurement, and Problem Solving 2 Chemistry is… • …the study of the composition, structure, properties, changes that occur in matter
Uploaded: 08/02/2017
33 Pages 255 Views 0 Unlocks
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1 Chapter OneMatter, Measurement, and  Problem Solving


How many sig figs are in each data?



2

Chemistry is…

• …the study of the composition, structure,  properties, changes that occur in matter. The properties of matter are  determined by the properties of  atoms and molecules.3 1.1 Atoms and Molecules

• Atoms are the tiny, fundamental building  blocks of matter. • Atoms usually bind together in nature,  forming molecules. (or ions. More later.) Why do we study atoms and molecules in such detail?  Because  THE PROPERTIES OF MATTER…4 1.2 The Scientific Approach to Knowledge


What arithmetic operations were performed?



We also discuss several other topics like How are the electrons distributed in the atom?
We also discuss several other topics like What is the most common way of introducing recombinant DNA into bacterial cells?

• Best method (so far) for generating new knowledge. • Data and results may be qualitative (general  observations) or quantitative (measurements).5 Scientific Laws • A scientific law is a statement (often  mathematical) of behavior that is always the  same under the same conditions. • Law: “This is what happens when XYZ…” • Boyle’s law: PV = a constant • Law of conservation of mass: Matter is neither created nor destroyed in a chemical reaction. Scientific Theories • A scientific theory is an explanation of a law.6 • A theory is NOT “an idea I just had.” Nor is it “a wild  guess I came up with while hung over from last night.” • Example: the Law of Conservation of Mass is explained  by atomic theory. Law: Mass of  rust = mass of  iron + mass of  oxygen. Theory: iron and  oxygen atoms  aren’t destroyed,  they’re just  rearranged, so  there is no  change in mass.Science is: • testable • reproducible • explanatory • predictive Science is not: 7 • fair • democratic • absolute • based on authority• • tentative 8 • based on  physical reality 1.3 The Classification of Matter


How many sig figs are in the data?



We also discuss several other topics like What would be the DWL from allowing these two industries to pollute as much as they want?

Classified according to states (phases)

• Solid: ٭ _______shape ٭ _______volume • Liquid: ٭ _______shape ٭ _______volume • Gas: ٭ _______shape ٭ _______volume

910 One  Composition of Matter

Multiple  component components11 Pure Substances and Mixtures

We also discuss several other topics like o Compensation- Lungs- increase respiratory rate to blow off that CO2 to get rid of hydrogen ions & correct that balance but how long can you breathe deep & fast?

• A pure substance (or just ‘substance’) has a  fixed composition, and is either an element or a  compound. • An element cannot be broken down into other  simpler substances by chemical reactions. • A compound can be broken down by chemical  reactions. • A mixture does not have a fixed composition.  Mixtures can be separated by physical means.12Separating Mixtures

13141.4: Physical and Chemical  Changes and Properties

We also discuss several other topics like the nurse is turning a client in bed. where would the nurse stand when using the friction-reducing sheet to turn the client to the opposite side of the bed?

Q: “Is XYZABC a chemical change?” A: “Have new substances been formed?”

15 Terms to Use: Properties

• A physical property can be observed without changing the composition of the matter. • To observe a chemical property there must be a  change in composition. Q: “Is XYZABC a chemical  property?” A: “Were new substances  formed when you observed  the property?”

Copper is red brown, opaque,  solid: ______  properties. Ethanol is flammable:  a ______ property.16 Terms to Use: Properties

• An extensive property depends on the amount of matter present. ٭Length, mass, volume • An intensive property …doesn’t. ٭Color, odor, density, temperature 1.5 Energy

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• Energy is the ability to do work: Potential energy,  kinetic energy, thermal energy, nuclear energy,  electrical energy, etc.17 • Work—transfer of energy from applying a force through a distance. • Heat—energy transfer that occurs from a temperature difference.Energy, like matter, is conserved.

18 1.6 Units of Measurement

• SI: le Système International d'unités • In SI, there is only one unit for each type of measurement.19 Metric Units and Prefixes

• Length: Meter • Mass: Kilogram • Time: Second • Temperature: Kelvin (not “degrees Kelvin”) • Derived units: ٭Volume: Liter (1 cubic decimeter), mL ٭Temperature: Degree Celsius (1 C°= 1 K)  ٭Area: Square meter (m2; also cm2, km2, etc.) ٭Volume: Cubic meter (m3; also km3, cm3, etc. 1  cm3 = 1 mL)20 Density: An Important Derived Unit

Density: ratio of mass to volume: m d = ––– V • Mass and volume are extensive properties, but… • …their ratio is an intensive property. • Any units of mass and volume may be used. • Density can be used as a conversion factor.Prefixes Change the Magnitude of the Unit

21221.7 Reliability of Measurements

23 The last digit in a scientific measurement is the first uncertain  digit.24Always estimate between graduations

25 Precision and Accuracy

• Accuracy: closeness of measurement to the  “true” (accepted) value. • Precision: repeatability, reproducibility. ٭We never know—CAN’T know—whether a  real measurement is accurate. ٭We usually make several measurements  and strive for precision, expecting that good precision implies good accuracy. (Not  necessarily true…)26 Significant Figures

Significant figure convention is designed so  that our results represent both the magnitude  and the precision of our measurements. 278 miles ————— = 23.76068376 mi/gal (calculator answer) 11.70 gallons Which one is the first  uncertain digit? 27 Using Sig Fig Conventions

• Significant figures – all the known digits, plus the  first uncertain digit. • The problem/calculation is completed before  considering the number of sig figs. 1. Work the entire problem/calculation to get the  “calculator” answer. 2. How many sig figs are in each data? 3. What arithmetic operations were performed? 4. Use #2 and #3 to determine the number of sig figs  that should be reported in the final answer. 5. Round off the final answer appropriately.How many sig figs are in the data?

28 • Begin counting with the first non-zero digit. • Stop at the end of the number. Exceptions: • Counting numbers, defined numbers, and most  conversion factors (2.54 cm = 1 in.) are considered to be exact (no uncertainty. • In exponential notation, the coefficient shows the  number of sig figs. (e.g., 3.40 × 1012 has 3 sig fig). • Numbers ending in zero(es) without a decimal (e.g., 500  mL, 2200 g) are ambiguous.How many sig figs should I report in the  final answer?

29 Base the number of sig figs in a result on measurements, not on  known values. • Multiplication and division: ٭Report the same number of significant figures as the  data with the fewest significant figures. • Addition and subtraction: ٭Report the same number of decimal places as the  data with the fewest decimal places. • Addition/subtraction AND multiplication/division: ٭Use the rules above to determine the number of sig  figs at each step in the calculation; continue until you  reach the final answer.30 1.8 Solving Chemical Problems

• Determine the nature of the answer (its  units); what are you trying to find? • Identify the given information: data,  numbers, observations, constants, material  you can look up, etc. • Devise a plan of attack.“Manuel, when faced with a problem you do not  understand, do any part of it that you do understand, then  look at it again.” --- R. Heinlein

31 Dimensional Analysis

A general problem-solving method involving  conversions. • Number × 1 = that same number. • Fraction = 1 when numerator = denominator. • The same quantity or unit in numerator and  denominator of a fraction will cancel. Conversion Factors

2.54 cm = 1 in. gives two conversion factors: 2.54 cm 1 in. ––––––– = 1 ––––––– = 132 1 in. 2.54 cm Now we can convert in. to cm or cm to in. Further Remarks on Solving Problems

• Does your answer represent physical reality? • A calculator always gives you an answer, but that answer is not always correct. Estimation can help determine  whether an answer is reasonable. • Using an equation? All the variables but one are in the  problem…somehow, somewhere. • Homework/exam problems: usually you are given just  enough information to solve the problem.33 • Real-world problems: you usually have either too much  information or not enough. Critical thinking is necessary.
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