of Diploma.
this investigation
was
to see whether
saturated
of common
the completely
considerations of Aim
the IB
Instead of
separate
the water
without solutions
adding any
ion was 37528.5
trials, the different measurements were taken after the μS/cm. After the addition of NaCl to the solution, it can
salts experience
common
ion effect or not be
and
if they experience
ion effect,
addition of soluble
the chemicals
to conserve
the chemicals.
obviously
seen that the common
conductivity
value decreases.
After
adding
11
g
of
NaCl
the
conductivity
value decreases
Aim of this investigation was to see whether saturated
the
aim
was
to
identify
the
relationship
between
the
solubility
of
the
completely
soluble
salt 1.1 clearly
solutions of the completely soluble salts experience to 31953.4 μS/cm. The shape of the Graph
common ion effect or not and if they experience suggests that as the mass of added of NaCl (common ion
and the mass of the common ion added. Solubility of KCl solution in water is observed with
the common ion effect, the aim was to identify the present ion the solution) increases, the solubility of KCl
relationship between the solubility of the completely decreases accordingly. The representation of the data
the increasing mass of added NaCl salt -which has Cl- ions in common-. The density of the free
soluble salt and the mass of the common ion added. can be seen in the following graph.
Solubility of
KCl in solution
in water
is observed
with the
ions
the solution
is directly
proportional
to solubility
of that
the solution
since ionic decreasing.
The gradient
of salt
the in
Graph
1.3 is constantly
increasing mass of added NaCl salt -which has Cl- ions
This feature of the graph suggests that, at some point
in common-.
The disassociate
density of the
the solution
salts
into free
their ions
ions in when
they dissolve.
During
the become
experiment,
the other
factors
gradient
would
zero that
the best
fit line would
is directly proportional to solubility of that salt in the
be parallel to the x-axis indicating that the addition
solution since
disassociate
into their
ions
when
that ionic
have salts
impact
on the solubility
like
temperature,
of solute, ions
waiting
time
and pressure
of amount
more common
to the
solution
would alter the
they dissolve. During the experiment, the other factors
solubility no more at that point. The equation of the
that have are
impact
on the solubility
like obtained
temperature,
kept constant.
The results
are as follows:
graph 1.3 is:
amount of solute, waiting time and pressure are kept
y = 24.76x2 – 772.8x
constant. The results obtained are as follows:
Mass of Added NaCl
to the Saturated
(4.7 M) KCl Solution
[g]
(± 0.001 g) The Mean Electrolytic
Conductivity Value of
the Solution
(Avg.)
[μS/cm] Uncertainty of The Mean
Electrolytic Conductivity
Value of the Solution
(ΔAvg.)
[μS/cm] Standard Deviation
[μS/cm]
0.000
3.000
5.000
7.000
9.000
11.000 37528.5
35249.5
34211.3
33445.8
32467.4
31953.4 191.0
295.0
476.4
180.1
340.0
135.8 133.9
203.1
337.3
140.4
274.4
91.2
Table 1.2 The Mean Electrolytic Conductivity of the Saturated (4.7 M) KCl Solution Depending on the Mass
of the Added NaCl and Uncertainty and the Standard Deviation Values of the Mean Conductivity Values
The hypothesis was that saturated completely soluble
salts would not experience the common ion effect in a
way that their solubility would not change after adding
the common ion, but the results obtained during the
investigation does not support the hypothesis. As seen in
the table 1.2, the electrical conductivity value of KCl salt in
Graph 1.3 The Mean Conductivity Value of the Solution vs
the Mass of NaCl Added
52
THE CLAPPER 2018 - 2019
it is quadratic-which means it has min or max value-
and it has a minimum value since the coefficient of x2
positive and this minimum value can be calculated by
differentiating the equation and equating it to zero.
y = 24.76x2 – 772.8x
dy/dx=2×24.76x-772.8 = 49.52 x- 772.8 = 0
49.52x = 772.8
x = 15.6 grams
It seems that the solubility KCl salt would not decrease
further after the addition of 15.6 grams of NaCl. This value
is the half of the mass of the KCl that can be dissolved
in 100 ml water at room temperature -The literature
value is obtained from the solubility curve in appendix
E-. The main reason for that situation is because at that
point, the mass of added NaCl would be almost equal
to the mass of KCl dissolved in the solution so that, KCl
would not be the solute that experiences the common
ion effect anymore. The mass of NaCl in the solution
would be bigger. From that point, it would be more likely