1 / 91

8/27/14

8/27/14. Today I will use the steps of the scientific method to solve problems. Warm Up – What is the scientific method?. Measurements and Math. Academic Chemistry Chapter 1 (Sections 4-7). Scientific Method. What is the scientific method?

gad
Télécharger la présentation

8/27/14

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 8/27/14 • Today I will use the steps of the scientific method to solve problems. • Warm Up – What is the scientific method?

  2. Measurements and Math Academic Chemistry Chapter 1 (Sections 4-7)

  3. Scientific Method • What is the scientific method? • A way of answering questions about the world we live in • Why do we use the scientific method? • Organization • Communication • Common sense

  4. Scientific Method • Steps • 1. Identify the problem or question • 2. Gather information and make observations • 3. Form a hypothesis • 4. Test the hypothesis (experiment) • 5. Analyze the data and form a conclusion

  5. Scientific Method • Hypothesis - • educated guess • can never truly prove correct • Theory – • well tested hypotheses about a topic • Law – • Hypothesis or theory that has been tested over and over and generally accepted as fact by the scientific community

  6. Scientific Method • Controlled experiment • Experimental Group – vary one variable while keeping all others constant • Control Group – do not make any changes in order to compare to the experimental group

  7. Scientific Method • Independent Variable • Variable that is changed in a scientific experiment • What we control • Dependent Variable • Variable that changes in relation to the independent variable • What we measure • Control Variables • Things we purposely keep constant in an experiment

  8. 8/28/14 • Today I will demonstrate the steps of the scientific method. • *Please take out your homework and put on your desk. • Warm Up – Find your pulse on your wrist or your neck. Count how many beats you feel in 10 seconds.

  9. 8/29/14 • Today I will review algebraic concepts. • Warm Up – Solve for x: 3(4x + 7) = 45

  10. 9/2/14 • Today I will measure objects to the correct degree of certainty Warm Up – I want to see if using the air conditioner in my car really uses more gas. If I design an experiment to test this, what is the dependent variable and what is the independent variable?

  11. What is Chemistry? • Chemistry – The study of matter and the changes it undergoes • The central science! • Chemistry overlaps so many other fields and professions!

  12. Measurements • A measurement consists of a number and a unit. • That boy is almost 7 tall. Seven what?? That boy is almost 7 feet tall.

  13. Measurement • Metric System • SI units – base units • Length - meter • Mass– gram (kilogram) • Volume - liter • Time – second • Temperature – Kelvin

  14. Measurement • Metric System • Derived units – made up of bases • Area → a = l x w Meter squared (m2) • Volume → v = l x h x w meter cubed (m3)

  15. Making Measurements • Uncertainty in measurement • When measuring, estimate the measurement to one place past the last place on the instrument. • Measuring Length

  16. Making measurements Remember to estimate! • Measuring Mass • Triple beam balance • Electric balance Estimation done for you!

  17. Making Measurements

  18. Making Measurements Measuring Volume • Volume of a liquid -read the bottom of the meniscus -usually mL

  19. Making Measurements Measuring Volume • Volume of a liquid • Volume of a regular solid -geometry equations -cm*cm*cm=cm3 -1mL = 1cm3 11.32 cm 6.85 cm 5.90 cm

  20. Making Measurements Measuring Volume • Volume of a liquid • Volume of a regular solid • Volume of an irregular solid -water displacement

  21. Reliability • Precision • Will give the same number over and over again • Accuracy • Will be close to the accepted value

  22. 9/3/14 • Today I will determine the number of significant figures in a number. • Warm Up- Measure the following with both rulers:

  23. Significant Figures • In measurements, the certain and estimated digits together are the significant figures.

  24. Significant Figures • Four easy rules!!! #1 All Nonzero numbers are SIGNIFICANT! 324.5

  25. Significant Figures • Four easy rules!!! #2 All “sandwiched” zeroes are SIGNIFICANT! 3204.05 3004.05

  26. Significant Figures • Four easy rules!!! #3 All leading zeroes are NEVER SIGNIFICANT! 0.0320405

  27. Significant Figures • Four easy rules!!! #4 Trailing zeroes are SIGNIFICANT if there is a decimal point anywhere in the number! 0.032040 3200 3200. 3200.00

  28. Significant Figure Practice • 0.057010 • 0.0026701 • 19.0550 • 3500 • 123 • 0.200 • 80000 • 5 significant figures • 5 significant figures • 6 significant figures • 2 significant figures • 3 significant figures • 3 significant figures • 1 significant figure

  29. Rounding • Round the following numbers to 3 significant figures: 0.057010 0.0026701 19.0550 35800 1232264 0.2 85421.55 1822449 Do I have the correct number of significant figures? Does the number still mean the same thing?

  30. Measuring & Sig Fig Practice • Use a ruler to measure the object given to the correct place. • How many significant figures does this number have?

  31. 9/4/14 • Today I will demonstrate measuring various quantities. • Warm Up – Describe the measurement process

  32. 9/5/14 • Today I will determine the number of significant figures in a calculation • Warm Up – How many significant figures are in the number : 0.002001100

  33. Significant Figures in Calculations • Multiplications and Division • The measurement with the smallest number of significant figures determines the number of significant figures in your answer.

  34. Significant Figures in Calculations • Multiplications and Division 3.052 m x 2.10 m x 0.75 m 2 4 3 = 4.8069 m3 = 4.8 m3

  35. Significant Figures in Calculations • Addition and Subtraction • The measurement with the largest uncertainty determines the number of significant figures in your answer.

  36. Significant Figures in Calculations • Addition and Subtraction 3.052 m - 2.10 m + 0.75 m = 1.702 m 3.052 m - 2.10 m +0.75 m 1.702 m = 1.70 m

  37. Significant Figures in Calculations • Addition and Subtraction 951.0 g + 1407 g + 23.911 g + 158.18 g 951.0 g 1407 g 23.911 g 158.18 g 2540.091 g = 2540. g

  38. 9/8/14 • Today I will convert numbers to scientific notation • Warm Up – Calculate the following to the correct number of significant figures: (3.440)(0.0021)(3009)

  39. Scientific Notation • For very large or very small numbers! • 1,000,000,000,000,000,000,000,000,000,000,000 • 0.00000000000000000000000000000000000001 Makes difficult numbers easier to use!

  40. Putting Numbers into Scientific Notation • For numbers greater than one: • 145,000 • Place a decimal point after the first significant figure • Add x 10 • Count the number of places the decimal moved and place it as a positive exponent on the ten. 5 x 10 1.45000

  41. Putting Numbers into Scientific Notation • For numbers less than one: • 0.01450 • Place a decimal point after the first significant figure • Add x 10 • Count the number of places the decimal moved and place it as a negative exponent on the ten. -2 x 10 1.450

  42. Putting Numbers into Regular Notation • For numbers greater than one (positive exponent): • 1.45 x 105 • Move the decimal to the right the number of spaces indicated by the exponent 145,000

  43. Putting Numbers into Regular Notation • For numbers less than one (negative exponent): • 1.450 x 10-2 • Move the decimal to the left the number of spaces indicated by the exponent 0.01450

  44. Scientific Notation • Remember!!! • Bignumbers are positive! • Small numbers are negative!

  45. Scientific Notation • Try these: • 432400000 • 0.0000000000003 = 4.324 x 108 = 3 x 10-13

  46. Calculators and Scientific Notation • To put this number into your calculator, you must use the exponent key. • Let’s find it!

  47. Calculators and Scientific Notation • 6.4 x 10-12 • To put this number into your calculator, you must use the exponent key. 6.4 EE -12

  48. Scientific Notation • Do this math on your calculator: • 2.34 x 106* 5.63 x 10-12 • 6.54 x 1013/ 4.31 x 102 • 2.3 x 103 + 5.3 x 102 • 4.2 x 1023 – 1.8 x 1022 = 1.32 x 10-5 = 1.52 x 1011 = 2.8 x 103 = 4.0 x 1023

  49. 9/9/14 • Today I will practice significant figures and scientific notation. • Warm Up – • Write 574000 in scientific notation • Write 2.1 x 107 in regular notation • Calculate: 2.1 x 103 ÷ 5.2 x 104 5.74 x 105 21000000 4.04 x 10-2 (0.0404)

More Related