Name:
Emily Tsiao
Quiz Section:
AD
ID Number:
930609
Lab Partner:
Hayley Smith
Total Points
= 60 (5 notebook, 55 template)
PURPOSE AND METHOD
DATA AND CALCULATIONS
A.
Flame emission determination of [K+] in the 0.50 M KCl + KHP (sat) solution
Preparation of Standards
DATA
50 mL of each standard solution (from prelab)
Solution
Intensity
Standard
[K+], (M)
mL of stock
Standard 1
7.50E05
84
1
7.50 E5
0.75
Standard 2
1.50E04
152
2
1.50 E4
1.50
Standard 3
2.25E04
222
3
2.25 E4
2.25
Standard 4
3.00E04
318
4
3.00 E4
3.00
Standard 5
3.75E04
373
5
3.75 E4
3.75
Intensity
23.2
229.8
3 pts
slope
9.92E+05
yintercept
6.6
Table 1
: Volume of 5.00x10
3
M needed to make
Table 2
: Flame Photometer Data
[K
+
], (M)
Temperature,
o
C
KHP(sat) in
0.50 M KCl
M
1
How are the solubility products (K
sp
) of KHP at various temperatures determined? (
3 pts
)
In order to calculate the Ksp of KHP at various temperatures, we titrate saturated KHP solutions at various temperatures with a standardized NaOH solution.
Using data from these titrations, we can calculate the moles of NaOH added at equilibrium, which is equal to the moles of KHP in the solution.
then, using the
amount of KHP in the original solution, we can determine the molarity of HP^ in each of the solutions.
Because each solution is saturated and KHP
dissociates in a 1:1 ratio, we know that [HP^] is equal to [K^+], thus we can calculate Ksp using the equation:
Ksp =[HP
^
][K^+].
How
is K
sp
in a saturated solution of KHP in 0.50 M KCl determined?
(3
pts
)
In order to calculate Ksp of a saturated KHP solution in the presence of a common ion (from 0.50 M KCl), we calculate [K^+] and [HP^] individually.
The
[HP^] is found by titrating the KHP/KCl mixture with the standardized NaOH solution in the same way as Part B.
To calculate [K^+], though, we compare
the intensity of a diluted KHP/KCl solution (using a flame photometer) to a group of standard solutions.
In creating a calibration curve of the standard
solutions, we can calculate [K^+] of the diluted sample from the intensity reading,
Using this value, we can calculate the [K^+] of the initial solution by
mathematically undoing the solution.
EXPERIMENT 4: THERMODYNAMICS II
THE TEMPERATURE DEPENDENCE OF THE SOLUBILITY PRODUCT, HEAT OF SOLUTION, AND
ENTROPY OF SOLUTION OF POTASSIUM HYDROGEN PHTHALATE
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 Spring '08
 Chiu
 Solubility, ml, Sodium hydroxide, Ksp Values

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