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Title: CHEM 1402 Postlab Report
Description: Determining the Percent Composition of Salt Solutions-Postlab Report
Description: Determining the Percent Composition of Salt Solutions-Postlab Report
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Running head: DETERMINING PERCENT COMPOSITION OF SALT SOLUTIONS
Determining the Percent Composition of Salt Solutions-Postlab Report
Brianna Marsh
Partners: Aaron A, Edie J, Matt W
...
This was done by measuring the mass, volume, and calculating the density of multiple known
compositions (0%,5%,10%,15%,20%)
...
After this students picked two unknown
solutions and measured the mass, volume, and calculated the density of each
...
And students determined where the unknown solutions fell
on the graph from the first section of the experiment
...
Table 1: Measured Known Values
% NaCl
Trial
0
5
10
15
20
Volume (mL)
Mass (g)
Density (g/mL)
1
10
9
...
98
2
10
9
...
95
3
10
9
...
96
1
10
10
...
02
2
10
10
...
01
3
10
9
...
99
1
10
10
...
05
2
10
10
...
04
3
10
10
...
04
1
10
10
...
07
2
10
10
...
07
3
10
10
...
07
1
10
10
...
09
2
10
10
...
09
3
10
11
...
11
Average
Density (g/mL)
0
...
01
1
...
07
1
...
963
5
1
...
04
15
1
...
10
Figure 1: Percent Composition of Known Substances
Table 3: Measured Unknown Values
container
number
Trial
3
5
Volume (mL)
Mass (g)
Density (g/mL)
1
10
10
...
05
2
10
10
...
05
3
10
10
...
08
1
10
10
...
09
2
10
10
...
08
3
10
11
1
...
06
1
...
5% , 5- 15
...
0067x +
...
0067 (% N aCl) +
...
06 =
...
9698
7
...
06−
...
0067
|actual−theoretical|
actual
|12
...
46|
12
...
46%
*repeat steps for unknown 5
average
density (g/mL)
unknown
percent
composition
percent error
3
1
...
46
7
...
09
17
...
6
Description of Data:
Table 1 expresses the volume (in milliliters), mass (in grams), and density (in grams per
milliliters) that the students measured three times for each known percent composition substance
...
Table 2 is a condensed
version of the first table, only expressing the percent composition and the measured average
density
...
The values of table 2 were plotted in a line graph, and then a more even trend line
was drawn through this graph
...
DETERMINING THE PERCENT COMPOSITION OF SALT SOLUTIONS
5
Table 3 is set up in the same manner as Table 1
...
The last column being the calculated average density of each unknown substance from all three
trials
...
These
values were then used to calculate percent composition and percent error in the next two
columns
...
Discussion
There were two parts to this experiment
...
This graph was used to
calculate the slope of the data and the R^2 value which would be useful in part 2 of the
experiment
...
99, meaning that there was
a small variation between the calibration curve and the trend line and a high reliability in the
data
...
Then the actual percent
composition was given by the instructor
...
Based on the group’s calculations, the percent error was quite high for both of the
unknown substances (over 5%)
...
The accuracy of the data was quite skewed
...
And it couldn’t have been due
to experimental design
...
The only possible reason for the low R^2 value and high percent error would
DETERMINING THE PERCENT COMPOSITION OF SALT SOLUTIONS
6
have to be simple human error
...
Or possibly not closing the case on the scale all
the way and letting wind or any other factors shift the scale
...
Conclusion
The average density of 10mL of different percent concentrations of salt water can be
proved through the trend line on the graph
...
The high reliability of the first part of the experiment proved
little error in the results but the second part of the experiment showed high percent of error due
to unpredictable, yet preventable, circumstances
...
Title: CHEM 1402 Postlab Report
Description: Determining the Percent Composition of Salt Solutions-Postlab Report
Description: Determining the Percent Composition of Salt Solutions-Postlab Report