1 / 24

Do Now

Do Now. Take out homework packet, do #1 on page 19. Measurement Quiz. Tonight's Homework. Read page 9-10 for the next topic Homework Packet p 19+20 Watch Rosengartens video (1.03 rounding) and take a look at the homework (3).

scot
Download Presentation

Do Now

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. Do Now • Take out homework packet, do #1 on page 19

  2. Measurement Quiz

  3. Tonight's Homework • Read page 9-10 for the next topic • Homework Packet p 19+20 • Watch Rosengartens video (1.03 rounding) and take a look at the homework (3). • Write down at least 2 questions to ask for the next class. There will be questions on the daily quiz from the reading (15 minutes)

  4. Todays Goal • Be able to determine a numbers precision and the number of significant figures • Take out your note packets and turn to page 7

  5. What the heck are significant figures? • Good question…… • Significant = important • Figures = numbers • Aren’t all numbers important? • Not always

  6. Significant vs. Insignificant • Numbers we know for sure from measurement are significant • Numbers that we don’t know are not • Example: • 13.5 ml • Precision was to the tenths, so we know all of those numbers for sure • 210 g • Our precision stopped at the 1 in the tens place • We don’t know what the zero is so it is not significant

  7. Significant vs. Insignificant • 00031 g • Do the zeros to the left count for anything? • No, they are insignificant • Zeros to the LEFT of the first integer are insignificant • .00073 l • The 7 and 3 are significant.

  8. Determining the number of Sig figs • 1) Look at the number • 2) Determine what the precision is • 3) Count from the left to the right, starting with the first non-zero and ending at the precision • 132.1 g

  9. Number Does it have a decimal? No Yes Precision is farthest # on right Precision is right most non-zero or a zero w/a line over it Count from the left most non-zero to the precision

  10. What is precision? • Being exact and accurate

  11. 2) Rosengartens rules for determining precision • How numbers are written will tell you the precision of the number • 1) If the measurement has a decimal point in it, the precision is the place furthest to the right in the measurement • Ex: 23.004 cm • Precision is to the thousandths

  12. More examples • 0.3320 g • Ten thousandths • 330. mL • Ones

  13. If the measurement does not have a decimal point in it… • The precision is the place where either the rightmost integer is, or where a zero with a line over it is (p8) • 2300 km • Hundreds

  14. More Examples • 1700 g • 1,000,000 joules • 17 ml • 10 ml

  15. Rosengarten’s Rule for Sig Fig’s • The number of significant figures in a measurement equals the total number of digits from and including the first (leftmost) integer in the measurement all the way to the limit of precision of that measurement. • Ex; 23.285 cm • Precision is to the…….. • Thousandths….so how many sig figs? • 5!

  16. To the tune of “To the left” • To the left, to the left, start counting at the first non-zero to the left • Count To the right till you reach the precision

  17. 3100 m • So how many sig figs? • 3100 m precision ends at the #1 • Count from the first non-zero on the left, to the precision…. • 2 sig figs

  18. What about 3100. m? • Oooo, a decimal point! What does that mean for the precision? • 3100. Precise to the 0 in the ones place • Count from the first non-zero on the left to the precision…. • 4 sig figs!

  19. What if it was a small number? • Lets say; 0.09053 kJ • Precision is to the…..hundred thousandths • .09053 kJ • Count from the first non-zero number on the left (9) to the precision. How many sig figs? • 4 sig figs!

  20. Wait, why ignore the 0 in the tenths? • Its kind of like all the 0’s that are to the left of any number. • 3200 m could be written 000003200 m • The zeros to the left of the first number are insignificant

  21. Ex: 0.050600 mol • Precision? • Millionths place; 0.050600 • First non-zero number; 0.050600 • Total number of sig figs? • 5

  22. Practice: How many sig figs • 2310. g • .09 km • 2300.100 J • 3.14 mg • 56.364327 L

  23. Cool • Take this time to do your homework (#2, p 19-20) and have me check it • YOUR HOMEWORK FOR TONIGHT • Read page 9-10 for the next topic, watch Rosengartens video (1.03 rounding) and take a look at the homework (3). Write down at least 2 questions to ask for the next class. There will be questions on the daily quiz from the reading • Check out wcsdchem.wordpress.com

More Related