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Turn in Homework to the front! 9/5 Warm Up

Turn in Homework to the front! 9/5 Warm Up. 1. Explain the difference between a physical and chemical change. 2. Explain the difference between homogenous and heterogeneous mixtures. 3. What are 3 ways that a mixture can be separated?. 2.2 & 2.3 & 2.4 Notes. Simplest form of matter

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Turn in Homework to the front! 9/5 Warm Up

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  1. Turn in Homework to the front!9/5 Warm Up 1. Explain the difference between a physical and chemical change. 2. Explain the difference between homogenous and heterogeneous mixtures. 3. What are 3 ways that a mixture can be separated?

  2. 2.2 & 2.3 & 2.4 Notes

  3. Simplest form of matter Can NOT be separated into simpler substances by chemical means Building blocks of other substances Examples: oxygen, hydrogen, etc 2 or more elements combined Substance that can be separated into simpler substances by chemical means H2O Element vs. Compound

  4. Properties of compounds compared to the elements • Sugar, C6H12O6: sweet, white, edible • Carbon, C: black, tasteless solid • Other interesting examples • Salt, NaCl 2 Na + Cl2 = 2 NaCl

  5. Symbols and Formulas • Chemical Symbol: a one or two letter symbol for the name of an element • Element symbols that you must memorize the name!!!! C H He N O P S Na Mg K Ca Cl F Al Fe Cu Ag Au Hg Pb Sn

  6. Chemical Reactions: Chemical Change • Changing reactants to products • Reactants: starting substances • Products: substances that are formed • Equation example • Reactants  Products • H2 + I2  2 HI(g)

  7. Journal #4 : Write down the following chemical reaction • NH4NO3 N2 + O2 + H2O • Label the reactants and products

  8. Conservation of Mass • Mass is neither created nor destroyed • Total mass of reactants = total mass of products

  9. Journal # 5 NH4NO3 N2 + O2 + H2O • When 20 grams of ammonium nitrate (NH4NO3) break down, 7 grams nitrogen (N2) and 4 grams of oxygen (O2) form. • How many grams of water are formed?

  10. Journal # 5 Answer • NH4NO3 N2 + O2 + H2O 20 grams = 7 g + 4 g + X g • When of ammonium nitrate (NH4NO3) break down, 7 grams nitrogen and 4 grams of oxygen form. How many grams of water are formed? • X = 20 - 7- 4 = 9

  11. During any chemical reaction, the amount of matter is unchanged!!! • Mass is neither created nor destroyed • Matter is neither created nor destroyed

  12. 3.1 The Importance of Measurement

  13. Scientific Notation • Mathematical abbreviation for measured values • Coefficient x 10n • The coefficient is greater than or equal to one and less that 10. • Example: 67,500,000,000,000.0 Decimal moves 13 places to the left 6.75 x 1013

  14. Example: 0.00000489 Decimal moves 6 places to the right 4.89x10-6

  15. Journal Now its your turn!!!! Convert the following values into scientific notation: • 86700000 • 0.00000052 • 63100

  16. Journal Now its your turn!!!! Convert the following values into scientific notation: • 86700000 = 8.67 x 107 • 0.00000052 = 5.2 x 10-7 • 63100 = 6.31 x 104

  17. Accuracy • Measure of how close a measurement comes to to the actual or true value of whatever is measured

  18. Precision • Measure of how close a series of measurement are to one another • Depends on more than one measurement!

  19. Error • Error = accepted value - experimental value • Percent error = ___|error | ___ x 100 accepted value

  20. Journal • Error = accepted value - experimental value • Percent error = ___|error | ___ x 100 % accepted value You measured the diameter of a ball to be 0.489 m. The package states that the ball has a diameter of 0.5 m. Identify the error and percent error of your measurement.

  21. You measured the diameter of a ball to be 0.489 m. The package states that the ball has a diameter of 0.5 m • Error: 0.5 - 0.489 = 0.011 • Percent error = 0.011 x 100 = 2.2 % 0.5

  22. Significant Figures How do we round in Chemistry??? Significant Figures give the reader an idea of how well you could actually measure/report your data. Rules for significant figures. 1) ALL non-zero numbers (1,2,3,4,5,6,7,8,9) are ALWAYS significant. 2) ALL zeroes between non-zero numbers are ALWAYS significant. 3) ALL zeroes which are SIMULTANEOUSLY to the right of the decimal point AND at the end of the number are ALWAYS significant. (2.400) 4) ALL zeroes which are to the left of a written decimal point and are in a number >= 10 are ALWAYS significant. (300.0)

  23. How Many sig figs? • 49,582 has 5 sig figs • 3.967 has 4 sig figs • 9.006 has 4 sig figs • 0.0004 has 1 sig fig • 8.1000 has 5 sig sig figs • 501.040 has 6 sig figs • 3,000,000 has 1 sig fig • 10.0 has 3 sig figs

  24. Using rounding in calculations • Addition/Subtraction: The answer to an addition or subtraction problem should be rounded to the same number of decimal places as the measurement with the least number of decimal places. • Example: 900.049 + 2.2 = 902.249 needs to be rounded to 902.2

  25. Multiplication/Division: answer needs to be rounded to the same number of significant figures as the measurement with the least number of significant figures • Example: 200 x 4.579 = 915.8 needs to be rounded to contain only 1 significant figure so your answer is 900

  26. The End

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