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Measurements & Math

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Measurements & Math

- Numbers determined by counting or by definition
- Ex: 6 apples, 1 teacher
- 1 inch=2.54 cm

- Numbers are based on MEASUREMENTS made in the lab.
- Our data is only as good as the measurements we make and the instruments we use.

- Observation that DOES NOT involve a number/measurement
- EX. Presence of odor, color change

- Observation that DOES involve a number/measurement (has magnitude size or amount)
- Ex. Length, mass, volume

- Accuracy: how close a measured value is to the actual (true) value.
- Precision: how close the measured values are to each other.

- Shows how PRECISE a measurement is
- Indicates the QUALITY of the instrument you use (how sensitive or exact)
EX. Graduated cylinder vs. beaker

5 sig figs

- 5432.1
- 0.00032
- 4004
- 82.0000

2 sig figs

4 sig figs

6 sig figs

- Used to write really LARGE or really small #’s
- Why? To save space & time

- Written in the form of m x 10n
- m: ≥ 1 AND <10
indicate the number of sig. figs

- Step 1) Determine the sig figs
- 106,000,000 = 3 sig figs

- Step 2) Determine the value of M using the sig figs
- 1.06 (remember this must be between 1 and 10)

- Step 3) Add the 10’s multiplier
- 1.06 x 10n

- Step 4) Determine the value of “n” by counting the number of times you move the decimal in the original number to get the value for “M”
- Step 5) Determine the sign of “n” by looking at the direction that you moved the decimal
- Move decimal to left = “n” is positive
- Move decimal to right = “n” is negative

- Ex. 1) 7,801
- Ex. 2) 0.00030

7.801 x 103

3.0 x 10-4

- Ex. 1) 3.1 x 104
- Ex. 2) 4.08 x 10-6

31,000

0.00000408

- One system for all scientists around the world
- We must have a standard for comparison
length – meter (m)

mass – kilogram(kg)

time – second (s)

volume – liter (L)

- Added to base units to represent large or smaller quantities
SI Prefix Unit Abbreviation Exponential Factor

kiloK103

hectoh102

dekada101

BASEm,g,s,L100

decid10-1

centic10-2

milli m10-3

King Henry Died By Drinking Chocolate Milk

10,000

- 10 g = ____________mg?

K h da b d c m

- 14.6 dL= __________ kL