> 9;8U@ *(bjbj "*d 4$4"$$$$$$$qR~H- H u
" "
"
0A
j"0A
jA44 A
HH44
44Dealing with Data
Chemical data may be qualitative or quantitative
Qualitative data is descriptive data possibly representing traits, properties, or characteristics
Such data is often represented in narrative form, sometimes
with accompanying diagrams (e.g. flow chart)
Quantitative data may be expressed in a variety of forms, one being common; the form of a table
The table may be detailed or fairly simple
The table should make data easy to find, easy to interpret, and relationships obvious
Information in the table should be well identified and include proper significance and units
Quantitative data may also be represented by graphs, of which there are many forms (pie, bar, line, etc.)
Graphs (line graphs) also make interpretation of data easier; they may especially focus upon interrelationships between two variables or descriptions of rate
This is a nice feature as most experiments have two variables, the independent and the dependent
Note: not all graphs imply interdependence however
Relationships between variables may be:
Direct
As one variable increases, the other variable increases and the converse is true
Inverse
As one variable increases, the other variable decreases and the converse is true
Proportional (directly or inversely)
The rate at which the variables change is constant
Such relationships may be expressed mathematically
Graphing Page 2
Components of creating a graph
ALL graphs require a descriptive/ germane title one that indicates what is represented by the graph.
Graphs may be generated by computer or manually.
Hand drawn graphs should employ the use of a straight edge, French curve, or flexible curve, etc.
The data should be tabulated and then the graph developed.
The axes should be labeled providing a description and a unit.
The x axis is called the _______________________ and
represents the independent variable.
The y axis is called the ________________________ and
represents the dependent variable.
Each of the axes needs to be calibrated. The scale needs to cover the maximum and minimum values to be represented. The intersection of the axes is often an origin of (0,0), however, there may be some exception to this rule.
The graduations should be easily identified. Divide the difference between the maximum and minimum values by the number of blocks or scores and round to a convenient larger value. These values should remain constant for the entire axis.
The scales should create a graph that utilizes most of the graph paper.
All data should be clearly marked with a dot or dot and circle, etc.
For multiple sets of data, utilize different symbols or colors to represent the different trials or sets.
A smooth curve should be drawn through the points. The curve should encompass as many points as possible, but should not be drawn point to point.
Graphing Page 3
Again, different colors or line designs (solid, broken, broken with dots, etc.) should be used in expressing different trials or sets of data.
If the relationship appears to be linear, draw a straight line as close to the set of points as possible and have about equal numbers of points above and below the line as possible.
Remember, experimental data is seldom ideal.
This line is referred to as the line of best fit. It may be extended beyond the set of real data. This is called extrapolation. When doing so the line of best fit should transition from being solid to a broken or dashed line.
For linear relationships a mathematical equation may be generated. For linearly and proportional relationships the equation applicable may be:
y = m x + b
Inversely proportional relationships may appear as:
y = m (1/x) + b
These equations include a slope, m, which is constant throughout the relationship.
Slope is the rise over the run or mathematically:
m = y / x = (y2 y1) / (x2 x1)
(Hint: determining slope utilize two points on the line which are not actual data points)
A word about significant figures; when reading a graph, the same significance should result be present as was associate
*MNfg*,46BDLNRT(*(Uh-16h-%CJ
h-16CJH*h-%56OJQJ\]^Jh-165CJ\h-%5CJ\h-16h-165>*CJ
h-16CJ
h-%CJh-%D r Q
R
[ -~
@^@p^p^^*(
?
@
u
v
H(a
p^p^^gd-16QNfgTUgh9:T ^`gd-16^gd-16^TV*(gd-16^d with the data used to create the graph.
1h/ =!"#$%@@@NormalCJ_HaJmH sH tH 8@8 Heading 1$@&CJ \@\ Heading 2$<@& 56CJOJQJ\]^JaJV@V Heading 3$<@&5CJOJQJ\^JaJDA@DDefault Paragraph FontVi@VTable Normal :V44
la(k@(No Listd*DrQR[ -~?@uvH(a
Q
Nfg
TUgh9:def
;0
;0
;0
;0
;0
;0
;0
;0
;0
;0
;0
;0
;0
;0
;0
;0
;0
;0
;0
;0
;0
;0
;0
;0
;0
;0
;0
;0
;0
;000000x0x0000000000000000000000 0x0000000000000000000000000*(
T*(*(ACFHfgq W[;?f33333333Mf
hhHcffEric D. GarmanEric D. GarmanEric GarmanEric GarmanEric GarmanEric GarmanEric D. GarmanEric D. GarmanEric D. Garman-%-16@cc||cc(::d0@00P@UnknownGz Times New Roman5Symbol3&z Arial"qhDz&Dz& r
r
!24d\\3H(?-16Dealing with DataEric D. GarmanEric GarmanOh+'0
<H
T`hpxDealing with DatadealEric D. GarmantricricNormal Eric Garman2icMicrosoft Word 10.0@vA@Hy+@Hy+r
՜.+,0hp
Owen J Roberts School Districtl\{
Dealing with DataTitle
!"#$%&')*+,-./1234567:Root Entry F0A<Data
1TableAWordDocument"*SummaryInformation((DocumentSummaryInformation80CompObjj
FMicrosoft Word Document
MSWordDocWord.Document.89q