Post on 02-Jan-2016
MATTER & MEASUREMENTS
Learning
Properties & Types of Matter
Changes
Math & Metric System; Numbers
Precision/Accuracy
E: energy subst: substance rxn: reaction w/: with w/o: without : change amt: amount
Learning Chemistry
Requires you to bring together new concepts & devel new skillsNeed to devel good study habitsDon’t FALL BEHINDFocus your studyGood notesText material before classReview material before classLearn language of ChemMake use of resources
Ch. 1lays foundation to your study
Chem all around impacts our lives; health care, environment, our needs
Other fields bio, geo, engr, arts, ag
MATTERmass & vol
3 States Solid - def shape, def vol, not compressibleLiquid - def vol, shape of container, not compressibleGas -vapor, not def shape/vol, highly compressible
S: molecules heldtightly in fixed
position
G: molecules far apart,no specific arrangement,move high speed, collide
w/ each other & wall
L: molecules closetogether in random
motion
Physical Change state (s-l-g) but not composition phy appearance
What effect does incr Temp cause?
Classification diagram, pg 11
MATTERmass & vol
HETROGENEOUS Mixture diff throughout
HOMOGENEOUS same throughout
MIXTURE SOLN
PURE SUBST
VariableComposition
g, l, s
uniformthru-out
NO YES
NO YES
minerals
liquids
solnLi2CO3
gasCH3CH2CH3
dry cmpdAgNO3
oceantable saltNaCl
PROPERTIES
Extensive \ Intensive additive non-
What examples of 2 diff subst can be combined?#1: 50 ml @ 25oC #2: 100 ml @ 50oC
volume
METRIC SYSTEMDimensional Analysis/Factor Label
500 yd to inches? conversion factors: 1 yd = 36 in 1 yd = 3ft & 1 ft = 12 in
factor-label method UNITGIVEN
UNIT toconversion*1 UNITGIVEN
in yd 1in 36 *
1yd 500
look at the“unit labels”
in ft 1in 12
yd 1ft 3 *
1yd 500
Base Units length: meters, mmass: grams, gvolume: liters, l (L)
Relationship:
1 ml = 1 cm3
Mass Weight
Based on quantity of matter presentNot affected by gravity
Affected by gravitational force
BASE: gram, meter, literg, m, l 100 = 1
decid 10-1
centic 10-2
millim 10-3
micro 10-6
dekada 101
hectoh 102
kilok 103
Mega; M; 106 Giga; G; 109 Tera; T; 1012
nano; n; 10-9 angstrom; ; 10-10 A o pico; p; 10-12
SMALLER: down
scale, move dec. pt. left LARGER: up scale,
move dec. pt. right
10-410-5
10-710-8 10-11
How many km is 745.26 cm?
100,000cm
km 1 * 1
cm 745.260.0074526
1.5*106 L to kL?
L 1
kL 9-10*1 * 1
L 610*1.5
L 910*1
kL 1 * 1
L 610*1.5
TEMPERATURE SCALES• Fahrenheit, Celsius, Kelvin
BOILING PT. FREEZING PT.
oF
oC
K
212o
100o
373.15o
32o
0o
273.15o
oF = (9/5 oC) + 32 oC = 5/9(oF - 32) K = 273.15 + oC
)cm (ml vol(g) mass Density
3or
mass perunit vol temp depend
GAS: g/L
table densities, pg 17
consider 2 Fe samples #1: 6 g @ 7.9 g/mL #2: 4 g @ 7.9 g/cm3
Which properties are intensive? mass or density
Measurements
exact number: all digit values known; definition or countdozen, 12 1 ft = 12 in 2.54 cm = 1 in
Where do they come from?
inexact: uncertainty in last digit value
SIGNIFICANT FIGURES
1. All nonzero digits are significant 5.37 cm 4.293g
2. Zeros between nonzero digits are sig. 106 ml 1.02 L
8.00 ml
23.0600 km
4. Zeros before the 1st nonzero digit in a number are not sig.0.002 g 0.060 * 10-3 mm 0.00000725 L
?3 ?4
?3 ?3
3
6
?1 ?2 ?3
500 500_
500_ _
?1 ?2 ?3
3. Zeros to the right of the dec. pt. at the end of a number are sig.
5. Zeros at the end of a whole number are sig. if a bar is over the zero; or decimal pt shown
500. ?3
Multiply / Divide Count sig. figures
152.06* 0.24
5.6 * 103
8.50
?36.4944
?36
= ?658.8235294 => ?660
or ?6.60*102
ACCURACY & PRECISION
Accuracy
• How close data points to “true” value
• 7.96 7.92 8.02
• 7.96 4.02 24.87
Accuracy
• Closeness of set of collected data to the “correct” or most probable value
ACCURACY & PRECISION
Precision
• Closeness of set of collected data among the data itself
Precision
• How close data points are to each other; grouped
• 0.997 0.999 1.003
• 1.325 0.046 5.263