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Mastering Measurements and Calculations for Scientific Problem-Solving

Explore scientific method, units of measurements, heat and temperature concepts, significant figures, and problem-solving techniques in chemistry. Learn about accuracy, precision, and proportional relationships. Includes examples and practical applications.

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Mastering Measurements and Calculations for Scientific Problem-Solving

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  1. Chapter 2 Measurements and Calculations

  2. Paper Cup Demo • http://www.youtube.com/watch?v=gQpUQu9bkAc&feature=related

  3. I. Scientific Method * a systematic approach to solving a problem (pp13) 1. State the problem 2. Gather information 3. Form hypothesis 4. Perform experiments 5. Record and analysis data 6. State conclusion

  4. II. Units of Measurements • Factor/Label: ex’s • Derived Units • Table 2-3 pp 36

  5. Density: = (m) / (v) units?? g/ml ***table 2-4 pp 38** • Volume: = (l) (w) (h) units?? cm3

  6. A. Heat and Temp *Temp: *Heat: ex’s: pp 511-512

  7. -Kelvin: • Freeze: 273.15 • Boil: 373.15 • K = (C) + 273 • 0 K is absolute 0

  8. Celsius • Freeze = 0 °C • Boil = 100 °C • ° C = (5/9) (F - 32)

  9. Fahrenheit: • Freeze = 32 °F • Boil = 212 °F • °F = (9/5) (°C) + 32

  10. -Units of Heat *Joule (J) *Calorie (c): c = 4.184

  11. Heat Cap. and Spec. Heat *HC: pp 513 Fig. 17-1

  12. Spec. Heat = heat lost or gained (J or Cal) mass(g) X ∆ in Temp (°C) Cp = ______q______ (m) (∆ T)

  13. Examples • Determine the specific heat of a material if a 35g sample absorbed 48 J as it was heated from 293 K to 313 K. A: .069 J/(g*K)

  14. Examples 2. How much heat is needed to raise the temperature of 5 g of gold by 25 C? A: 16 J

  15. Examples 3. If 980 kJ of energy are added to 6.2 L of water at 291 K, what will the final temperature of the water be? A: 329 K

  16. Elements Introduction • http://www.youtube.com/watch?v=DYW50F42ss8 • http://www.youtube.com/watch?v=AGZ20OrmYBs

  17. III. Scientific Measurements *Accuracy: *Precision: ex’s: pp 44 *Percent Error = Valueacc - Valueexp Valueacc

  18. *Significant Figures: ex’s: *Scientific Notation: • Move dec. right until only 1 nonzero digit remains • Determ Expo by the # of spaces moved--Left + Right -

  19. IV. Solving Quantitative Problems • Write what you know and what you are trying to find • Set up F/L parentheses • Get rid of unit • Bigger unit = 1 • Make a true statement in the parentheses

  20. Calculate • See if the answer is logical • Write units

  21. -Proportional Relationships • Directly: y/x = k or y = kx • Inversely: xy = k or y = k/x **ex’s and graphs http://mathcentral.uregina.ca/QQ/database/QQ.09.00/ellis1.html

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