The pH of the solution that contains the salt sodium fluoride is to be determined. Concept introduction: Salt is a strong electrolyte that dissociates completely when added to water. When a salt contains an anion that comes from a weak acid, the anion recombines with water to produce a weak acid and hydroxide ions, and forms a basic solution. The cation that comes from a strong base does not recombine and is present in the solution as a free ion without having any effect on the pH of the solution. The reaction of the salt ( BA ) that takes place is: A − ( a q ) + H 2 O ( l ) ⇌ HA ( a q ) + OH − ( a q ) Here, A − comes from the weak acid HA and B + comes from strong base BOH . The pH of this solution is determined by the [ OH − ] The relationship between K b , K a , and K w gives the quantitative basis of the reciprocal relationship between the strength of an acid and its conjugate base or vice-versa. K a × K b = K w …… (1) K b is the measure of dissociation of a base and is known as base-ionization constant, which is specific at a particular temperature. K b = [ OH − ] [ HA ] [ A − ] …… (2) The formula to calculate the pOH of the solution from the concentration of hydroxide ions is: pOH = − log [ OH − ] …… (3) pH is the measure of acidity of a solution that depends on the concentration of hydronium ions and temperature of the solution. The relationship between pH and pOH is: pH + pOH = 14 …… (4)
The pH of the solution that contains the salt sodium fluoride is to be determined. Concept introduction: Salt is a strong electrolyte that dissociates completely when added to water. When a salt contains an anion that comes from a weak acid, the anion recombines with water to produce a weak acid and hydroxide ions, and forms a basic solution. The cation that comes from a strong base does not recombine and is present in the solution as a free ion without having any effect on the pH of the solution. The reaction of the salt ( BA ) that takes place is: A − ( a q ) + H 2 O ( l ) ⇌ HA ( a q ) + OH − ( a q ) Here, A − comes from the weak acid HA and B + comes from strong base BOH . The pH of this solution is determined by the [ OH − ] The relationship between K b , K a , and K w gives the quantitative basis of the reciprocal relationship between the strength of an acid and its conjugate base or vice-versa. K a × K b = K w …… (1) K b is the measure of dissociation of a base and is known as base-ionization constant, which is specific at a particular temperature. K b = [ OH − ] [ HA ] [ A − ] …… (2) The formula to calculate the pOH of the solution from the concentration of hydroxide ions is: pOH = − log [ OH − ] …… (3) pH is the measure of acidity of a solution that depends on the concentration of hydronium ions and temperature of the solution. The relationship between pH and pOH is: pH + pOH = 14 …… (4)
Solution Summary: The author explains that the pH of the solution that contains the salt sodium fluoride is to be determined.
The pH of the solution that contains the salt sodium fluoride is to be determined.
Concept introduction:
Salt is a strong electrolyte that dissociates completely when added to water.
When a salt contains an anion that comes from a weak acid, the anion recombines with water to produce a weak acid and hydroxide ions, and forms a basic solution. The cation that comes from a strong base does not recombine and is present in the solution as a free ion without having any effect on the pH of the solution.
The reaction of the salt (BA) that takes place is:
A−(aq)+H2O(l)⇌HA(aq)+OH−(aq)
Here, A− comes from the weak acid HA and B+ comes from strong base BOH. The pH of this solution is determined by the [OH−]
The relationship between Kb, Ka, and Kw gives the quantitative basis of the reciprocal relationship between the strength of an acid and its conjugate base or vice-versa.
Ka×Kb=Kw …… (1)
Kb is the measure of dissociation of a base and is known as base-ionization constant, which is specific at a particular temperature.
Kb=[OH−][HA][A−] …… (2)
The formula to calculate the pOH of the solution from the concentration of hydroxide ions is:
pOH=−log[OH−] …… (3)
pH is the measure of acidity of a solution that depends on the concentration of hydronium ions and temperature of the solution. The relationship between pH and pOH is:
(a
4 shows scanning electron microscope (SEM) images of extruded
actions of packing bed for two capillary columns of different diameters,
al 750 (bottom image) and b) 30-μm-i.d. Both columns are packed with the
same stationary phase, spherical particles with 1-um diameter.
A) When the columns were prepared, the figure shows that the column with
the larger diameter has more packing irregularities. Explain this observation.
B) Predict what affect this should have on band broadening and discuss your
prediction using the van Deemter terms.
C) Does this figure support your explanations in application question 33?
Explain why or why not and make any changes in your answers in light of
this figure.
Figure 4 SEM images of
sections of packed columns
for a) 750 and b) 30-um-i.d.
capillary columns.³
fcrip
= ↓ bandwidth Il temp
32. What impact (increase, decrease, or no change) does each of the following conditions have on the individual
components of the van Deemter equation and consequently, band broadening?
Increase temperature
Longer column
Using a gas mobile phase
instead of liquid
Smaller particle stationary phase
Multiple Paths
Diffusion
Mass Transfer
34. Figure 3 shows Van Deemter plots for a solute molecule using different column inner diameters (i.d.).
A) Predict whether decreasing the column inner diameters increase or decrease bandwidth.
B) Predict which van Deemter equation coefficient (A, B, or C) has the greatest effect on increasing or
decreasing bandwidth as a function of i.d. and justify your answer.
Figure 3 Van Deemter plots for hydroquinone using different column inner diameters (i.d. in μm). The data was
obtained from liquid chromatography experiments using fused-silica capillary columns packed with 1.0-μm particles.
35
20
H(um)
큰 20
15
90
0+
1500
100
75
550
01
02
594
05
μ(cm/sec)
30
15
10
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