Download 1. Measurement

Metrics &
measurement



Volume: How much space something takes up,
measured in Liters or milliliters (cm3).
Mass(weight): measured in grams, milligrams
or kilograms.
Length: measured in meters, millimeters, or
centimeters.
The great advantage of using
metric units is that they are in
multiples of ten. This means
that you can simply move
decimal points to go from one
unit to another!







Kilo-K
Hecta-H
Deka-Dk
Base units= meters, Liters, grams
Deci-d
Centi-c
Milli-m
km
Hm dkm
m
dm
cm
mm
To change metric units, simple move the decimal
place along the scale from one unit to another. 25
meters becomes 2500 centimeters.
 23.5
g to mg (23,500 mg)
 435.7 ml to L (.4357 L)
 .223 km to m
(223m)
 22.57 cm to m (.2257 cm)
 450.3 L to ml
 45 mg to g
Find D for:
 A piece of cork with a volume of ml water that
weighs .41 grams. (.205 g/ml)
 A rock that displaces 10 ml water has a weight of 30
grams. (3 g/ml)
 A chunk of ice which has a volume of 25 ml weighs
23 grams. (.91 g/ml)






Significant Digits – the number of certain and
estimated digits in a number.
Zeroes to left of decimal point and to left of an
integer do not count as significant.
All other zeroes do count as significant.
31.76 (4 s.d.)is more accurate than 31.7 (3 s.d.)
.009210 (4 s.d.)
= 9.210 x 10-3
.0090210 (5 s.d.) = 9.0210 x 10-3
When doing math, your answer can only have as many
sigdigs as the lesser number of sigdigs:

1.12 + 2.243 = 3.363 = 3.36
(3 sigdigs) (4 sigdigs) (4 sigdigs) (3 sigdigs)
This answer can only have 3 significant digits since 1.12 only
has 3 digdigs.



The exponents you will use in this class
represent numbers which have the
number of decimal places in the
exponent 100 = 1; 101 = 10; 102 = 100 and
so on.
Positive exponents push the decimal
place to the right: 2.35 x 103 is 2,350
Negative exponents push the decimal
place to the left: 2.35 x 10-3 is .00235
When multiplying exponential
numbers, multiply the first two,
then add the exponents: 1.2 x 103 x
1.2 x 103 = 1.44 x 106
 When dividing exponential
numbers, divide the first two, then
subtract the exponents:
1.2 x 103 / 1.2 x 103 = 1.0 x 100 =1



To add exponents, move the decimal place to get
the same exponents, then add the numbers,
keeping the exponent. 1 x 102 + 1 x 103 = 1 x 102 + 10
x 102 = 11 x 102
To subtract exponents, move the decimal place to
get the same exponents, then subtract the numbers,
keeping the exponent. 1 x 103 - 1 x 102 =
10 x 102 - 1 x 102 = 9 x 102
 5.4
7
10
6
10
x
+ 2.7 x
=
16
15
 2.3 x 10 – 1.8 x 10 =
 8.4 x 1024 / 4.2 x 1022 =
 3.2 x 103 x 2 x 1012 =


Percent Yield = Actual x 100
Expected
Percent Error = Actual – Expected x 100
Expected



Used to convert units. Multiply the
given by the unit you want to find on
the top, and the unit you want to cancel
on the bottom.
10.5 mm = ? Meters
10.5 mm x 1 meter = .0105 meters
1,000 mm
Hot
Not?
or