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BQ #1

BQ #1. CONVERT 50 C to Kelvin C = K – 273.15. Measurements. Measurements (3.25 cm) are different than other numbers (3.14159265). Measurements represent an action by someone with some measuring instrument. Measurements have built-in uncertainty; no measurement is exact.

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BQ #1

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  1. BQ #1 CONVERT 50 C to Kelvin C = K – 273.15

  2. Measurements • Measurements (3.25 cm) are different than other numbers (3.14159265). • Measurements represent an action by someone with some measuring instrument. • Measurements have built-in uncertainty; no measurement is exact. • Measurements have units.

  3. Accuracy • Accuracy is how close a measured value is to the actual (true) value.

  4. Which one of these gives the most accurate reading?

  5. Precision • Precision is how close the measured values are to each other

  6. YOUR TURN

  7. Percent error • Lab activities are meant to be learning activities… so sometimes things can go wrong. • BUT we need do know how much our answers are “off” by… we use a formula called • THE PERCENT ERROR FORMULA

  8. THINGS TO NOTE • Absolute Value Bars • “accepted” vs. “measured” • X 100

  9. You Try • In lab you weigh a sample and find the mass to be 28.9 g. The correct mass is 27.0 g. Calculate your percent error.

  10. Step by Step • 27 g - 28.9 g • ABSOLUTE VALUE! -1.9 … DON’T PUT -1.9 in your calculator or you will be wrong • 1.9 / 27 = .0703 • .0703 X 100 = 7.03 • ANSWER= 7.03 % • Questions?

  11. Extra Practice • Turn to page 5 in your packet and we will work on # 1 and 2

  12. Matter and Its Properties • What is the difference between a physical and chemical change?

  13. Signs of Chemical Change • Change in temperature • Formation of a gas • Formation of a precipitate • Color change (sometimes)

  14. Endothermic Reactions • TAKE IN HEAT- (Feels cold to the touch)

  15. Exothermic Reaction • RELEASES HEAT!!!! (Feels hot to the touch)

  16. Three States of Matter • SOLID • LIQUID • GAS

  17. Your Turn • On page 18, answer question #2 and B • On page 26, answer question # 19

  18. Physical Vs Chemical Chemical Physical Chemical Physical • Iron Rusts • Ice Melts • Grass Grows • Salt Dissolves in Water

  19. Matter • First Question…. Looks the same throughout (one phase) Looks Different (has different phases) Heterogeneous Mixture

  20. Matter cont. Looks the same through out (one phase) Homogeneous Substance

  21. 3 types of homogeneous substances • 1. Elements – Made up of one type of atom (periodic table) 2. Solution- No set formula 3. Compound- Has a set formula

  22. Your Turn • Try number 5 on page 6 of your packet

  23. Tuesday: NO BQ

  24. Scientific Notation • Why write 54,300,000,000,000??? That’s a lot of ZEROS • We use Scientific notation to shorten numbers so that they are easier to work with. Packet Pg 4

  25. How do we do it? • If we have a large number like 2,400,000 we know that the decimal place is at the end of the number • 2,400,000. • In order to make it more manageable we move the decimal (TO THE LEFT) right behind the first non zero number. • Then we multiply by 10 and the exponent is the number of “bubbles” or places we moved the decimal…. Leaving us with…. Packet Pg 4

  26. What if it’s a SMALL number? • The same rules apply!! • This time we move the decimal to the RIGHT and the exponent becomes NEGATIVE Packet Pg 4

  27. Packet Pg 4

  28. Practice Time! • We will work through page 10 in your packet. If you don’t understand ASK QUESTIONS

  29. Significant Figures Packet Pg 4

  30. The Rules • 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. • 4) ALL zeroes which are to the left of a written decimal point and are in a number >= 10 are ALWAYS significant. • A helpful way to check rules 3 and 4 is to write the number in scientific notation. If you can/must get rid of the zeroes, then they are NOT significant. Packet Pg 4

  31. Atlantic- Pacific Rule • The Atlantic-Pacific Rule says: "If a decimal point is Present, ignore zeros on the Pacific (left) side. If the decimal point is Absent, ignore zeros on the Atlantic (right) side. Everything else is significant. Examples: (in your packet) 0.09587 85.00 4,000 Packet Pg 4

  32. Another hint • If you have a large number (or small number) and you can put it into scientific notation…. The numbers that are left are significant Packet Pg 4

  33. More Practice • Practice with the rest of the questions on page 5 (3-5) of your packet. And then page 9!

  34. BQ #2 • Please put you vocabulary on your desk and work on your BQ #2!

  35. SI System Packet Pg 6 • International System for measurement. Still used my all scientists- EVEN US!! • SI System is a base 10 system • We use it to study quantitative data… later we will study qualitative data

  36. The SI System • You must know these prefixes, symbols and meanings… Packet Pg 6

  37. CONVERSIONS

  38. Example problems • (Page 7 of your packet) • Example: Quarters to Dollars (What is the conversion factor?) • Example: Use your conversion factor to figure out how many quarters are in $75 • Your Turn: How many minutes are in 5 hours?

  39. And some more • Ex 2: Convert 62 km to m • Ex 3 Convert 3.2 L to daL • You Try: Convert 320 cm to m • Ex 4: Convert 17000 mg to kg • You try: convert 540 mm to dam

  40. Practice Makes Perfect • Page 8 1-6

  41. BQ Number 5 & 6

  42. Factor label method • This is the method that we are going to use for converting from unit to unit. • It makes the units act as the X in algebra. • Lets practice… Packet Pg 7

  43. Factor Label! • Page 7 • Ex: Convert 35 km to miles • Your Try: Convert 2.31 lbs to g • You Try: Convert 2 miles to meters

  44. MORE PRACTICE • Page 8- 7-12

  45. No BQ Happy Friday

  46. DOUBLE Factor Label • Example: 55 miles/hour to meters/min • Your Try: 12.0 g/mL to lb/ L

  47. Practice! • Page 8- 13-16- ASK QUESTIONS!!! We can go through these together

  48. On your own • Page 11 Conversion Practice • 1-8

  49. BQ- 7 & 8 • The formula for density is • Density= Mass • Volume

  50. Density! • (Page 11) • What is density? • The formula is…

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