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INTRODUCTION TO CHEMISTRY Systems of Measurement

INTRODUCTION TO CHEMISTRY Systems of Measurement. Professor Bob Kaplan University Department of Science. Measurement. Universe is composed of Particles or Elements Theory of mechanism Scientific method

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INTRODUCTION TO CHEMISTRY Systems of Measurement

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  1. INTRODUCTION TO CHEMISTRY Systems of Measurement Professor Bob Kaplan University Department of Science

  2. Measurement • Universe is composed of Particles or Elements • Theory of mechanism • Scientific method • Physical properties • Systems of measurement (English, SI) • Standardized units of measurement

  3. Chemistry

  4. Units of Measure • Qualitative observations are subjective as well as descriptive. • Quantitative observations are objective, and expressed numerically with specific units

  5. Units of Measure • A Unit is a defining quantity for a measurement. • The Unit of Measure tells what scale or standard is being used to measure. Units of Measurement: Grams , Meters , Degrees

  6. Units of Measure Numerical Value Real Number: 43.2 Unit of Measurement: Grams, Meters, Degrees E.G.  43.2  kg

  7. SI Units Mass: kilogram (kg) Length: meters (m) Time: seconds (s) Temperature: Degrees Fahrenheit (°F)

  8. Nutrients

  9. SI Units: Prefixes Numbers > 10 Factor Kilo: 103 1,000 Mega: 1061,000,000 Giga: 109 1,000,000,000

  10. SI Units: Prefixes Numbers < 10 Deci: 10(-1)= 0.1 of the unit Centi : 10(-2) = 0.01 of the unit Milli : 10(-3) = 0.001 of the unit Micro : 10(-6) = 0.000001 of the unit Nano : 10(-9)= 0.0000000001 of unit

  11. Silica Particles

  12. Length Length is the shortest distance between two points in space  1 - dimension SI Unit: Meter(slightly longer than one yard)

  13. Area  Area is the planar space determined by the intersection of two lines in space  2 - dimensions SI Unit of area  Square meters 1 sq meter = 1 m2 = 1.21 sq feet = 1.21 ft2

  14. Volume • Bulk quantity of space occupied by the intersection of two planes  3 - dimensions • SI Unit: Cube measures 1 meter on each edge Volume of the cube  =  length  x  width  x  height=  1 m  x  1 m  x  1 m=  1 cubic meter = 1 m3

  15. Length (1-d)Area(2-d) / Volume (3-d)

  16. Volume • If the cubic meter were divided into 1000 equal smaller parts,each part would be equal to 1 Liter (slightly larger than a quart) 1 qt = 1.057 L • If each liter were divided into 1000 equal smaller parts, each part would be equal to 1 milliliter (mL) or 1 cubic centimeter (cc)  1 mL = 1 cc  ~ 10 drops

  17. 1 Liter = 1000 mL

  18. Conversions 1 meter = 39.37 inches 1 meter = 1.1 feet 1 inch = 2.54 cm 1 km = 0.621 miles

  19. Volume Measurement Glassware Graduated Cylinder                 Volumetric Flask                      Pipet, Buret Syringe,Eyedropper

  20. Graduated cylinder

  21. Beakers

  22. Volumetric Flasks

  23. Burettes

  24. Mass • SI Unit: gram (g) or kilogram (kg) 1 kg = 1000 g • Determined by comparison with known standards on an analytical balance. 1 kg = 2.2 lb 454 g = 1.0 lb

  25. Density • General: Amount or number per unit of measure.e.g.  Number of dust particles per cubic foot e.g.  Number of  inhabitants per square mile (population density) • Physics & Chemistry:Amount of mass per unit volume Mass  /  Volume  =  m / v Units: g / ml   or   g / cc

  26. Density Values (g/mL) Cork 0.24 Wood 0.75 Water 1.00 Cement 3.00 Lead 11.30 Gold 19.30

  27. Temperature • Heat is the motion, or kinetic energy, of atoms and molecules. • Temperature is an average measure of the intensity of heat motion. • There are several scales used to measure temperature: Celsius (°C) Fahrenheit (°F) Kelvin (K)

  28. Fahrenheit Scale • When the doctor says that your temperature is 102 degrees,or the weatherperson says that it will be 75 degrees tomorrow, they are using the Fahrenheit Scale. Water Boils @ 212 °FWater Freezes @ 32 °F • Scale was designed by Gabriel Fahrenheit, who used the average temperature of the human body as his referent.

  29. Celsius Scale • Used in Canada & Europe,and in the physical and life sciences worldwide. Water Boils @ 100 °C Water Freezes @ 0 °C • This commonly used scale uses the points of phase transition (or states of matter) of water as its referent.

  30. Conversion: °C  °F • On both C and F scales, the unit of temperature is called a “degree”. • The size of the degree is different. 1 °C = 1.8 °F • The zero point of reference is shifted. °F  =  (1.8)°C  +  32 °C  =  (°F - 32)  / 1.8

  31. Kelvin(Absolute) Scale Zero Kelvin  No Atomic Motion Kelvin unit equivalent to Celsius degree. 1 Kelvin = 1 degree C °K = °C + 273WaterFreezes @ 273 °KWater Boils @ 373 °K O Kelvins = - 273 degrees °C

  32. Solving Problems • In the natural sciences, we use the technique of dimensional analysis for solving story problems with various units. • The key to this technique involves the use of conversion factors in order to obtain the correct units of measure.

  33. Conversion Factors 1) Eliminate the units given 2) Introduce the units required ** Express 40 grams in kilograms  (40 g) * (1 kg / 1000 g) = 0.04 kg *Note: 1 kg / 1000 g = 1000 g / kg

  34. Dimensional Analysis See handout in DocSharing Dim_anlys.doc Please review this document carefully. Other useful handouts posted include: Symbols.doc Formulas.doc

  35. “Please Return to Seminar…..” If you have come here directly from the SC155 Seminar session, please return to the KU course platform now to continue with the live session of discussion, questions and answers  See you all there !

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