# 8.3 Ph and poh  (Page 3/8)

 Page 3 / 8

## Calculation of poh

What are the pOH and the pH of a 0.0125- M solution of potassium hydroxide, KOH?

## Solution

Potassium hydroxide is a highly soluble ionic compound and completely dissociates when dissolved in dilute solution, yielding [OH ] = 0.0125 M :

$\text{pOH}=\text{−log}\left[{\text{OH}}^{\text{−}}\right]=\text{−log}\phantom{\rule{0.2em}{0ex}}0.0125$
$=\text{−}\left(-1.903\right)=1.903$

The pH can be found from the pOH:

$\text{pH}+\text{pOH}=14.00$
$\text{pH}=14.00-\text{pOH}=14.00-1.903=12.10$

The hydronium ion concentration of vinegar is approximately 4 $×$ 10 −3 M . What are the corresponding values of pOH and pH?

pOH = 11.6, pH = 2.4

The acidity of a solution is typically assessed experimentally by measurement of its pH. The pOH of a solution is not usually measured, as it is easily calculated from an experimentally determined pH value. The pH of a solution can be directly measured using a pH meter ( [link] ).

The pH of a solution may also be visually estimated using colored indicators ( [link] ).

## Key concepts and summary

The concentration of hydronium ion in a solution of an acid in water is greater than 1.0 $×$ 10 −7 M at 25 °C. The concentration of hydroxide ion in a solution of a base in water is greater than 1.0 $×$ 10 −7 M at 25 °C. The concentration of ${\text{H}}_{3}{\text{O}}^{\text{+}}$ in a solution can be expressed as the pH of the solution; pH = −log ${\text{H}}_{3}{\text{O}}^{\text{+}}.$ The concentration of OH can be expressed as the pOH of the solution: pOH = −log[OH ]. In pure water, pH = 7.00 and pOH = 7.00

## Key equations

• $\text{pH}=\text{−log}\left[{\text{H}}_{3}{\text{O}}^{\text{+}}\right]$
• pOH = −log[OH ]
• [H 3 O + ] = 10 −pH
• [OH ] = 10 −pOH
• pH + pOH = p K w = 14.00 at 25 °C

## Chemistry end of chapter exercises

Explain why a sample of pure water at 40 °C is neutral even though [H 3 O + ] = 1.7 $×$ 10 −7 M . K w is 2.9 $×$ 10 −14 at 40 °C.

In a neutral solution [H 3 O + ] = [OH ]. At 40 °C,
[H 3 O + ] = [OH ] = (2.910 −14 ) 1/2 = 1.7 $×$ 10 −7 .

The ionization constant for water ( K w ) is 2.9 $×$ 10 −14 at 40 °C. Calculate [H 3 O + ], [OH ], pH, and pOH for pure water at 40 °C.

The ionization constant for water ( K w ) is 9.311 $×$ 10 −14 at 60 °C. Calculate [H 3 O + ], [OH ], pH, and pOH for pure water at 60 °C.

x = 3.051 $×$ 10 −7 M = [H 3 O + ] = [OH ]
pH = −log3.051 $×$ 10 −7 = −(−6.5156) = 6.5156
pOH = pH = 6.5156

Calculate the pH and the pOH of each of the following solutions at 25 °C for which the substances ionize completely:

(a) 0.200 M HCl

(b) 0.0143 M NaOH

(c) 3.0 M HNO 3

(d) 0.0031 M Ca(OH) 2

Calculate the pH and the pOH of each of the following solutions at 25 °C for which the substances ionize completely:

(a) 0.000259 M HClO 4

(b) 0.21 M NaOH

(c) 0.000071 M Ba(OH) 2

(d) 2.5 M KOH

(a) pH = 3.587; pOH = 10.413; (b) pH = 0.68; pOH = 13.32; (c) pOH = 3.85; pH = 10.15; (d) pH = −0.40; pOH = 14.4

What are the pH and pOH of a solution of 2.0 M HCl, which ionizes completely?

What are the hydronium and hydroxide ion concentrations in a solution whose pH is 6.52?

[H 3 O + ] = 3.0 $×$ 10 −7 M ; [OH ] = 3.3 $×$ 10 −8 M

Calculate the hydrogen ion concentration and the hydroxide ion concentration in wine from its pH. See [link] for useful information.

Calculate the hydronium ion concentration and the hydroxide ion concentration in lime juice from its pH. See [link] for useful information.

[H 3 O + ] = 1 $×$ 10 −2 M ; [OH ] = 1 $×$ 10 −12 M

The hydronium ion concentration in a sample of rainwater is found to be 1.7 $×$ 10 −6 M at 25 °C. What is the concentration of hydroxide ions in the rainwater?

The hydroxide ion concentration in household ammonia is 3.2 $×$ 10 −3 M at 25 °C. What is the concentration of hydronium ions in the solution?

[OH ] = 3.1 $×$ 10 −12 M

Do somebody tell me a best nano engineering book for beginners?
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
what is the Synthesis, properties,and applications of carbon nano chemistry
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
what is nano technology
what is system testing?
preparation of nanomaterial
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
what is system testing
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
how did you get the value of 2000N.What calculations are needed to arrive at it
Privacy Information Security Software Version 1.1a
Good
how do you find theWhat are the wavelengths and energies per photon of two lines
The eyes of some reptiles are sensitive to 850 nm light. If the minimum energy to trigger the receptor at this wavelength is 3.15 x 10-14 J, what is the minimum number of 850 nm photons that must hit the receptor in order for it to be triggered?
A teaspoon of the carbohydrate sucrose contains 16 calories, what is the mass of one teaspoo of sucrose if the average number of calories for carbohydrate is 4.1 calories/g?
4. On the basis of dipole moments and/or hydrogen bonding, explain in a qualitative way the differences in the boiling points of acetone (56.2 °C) and 1-propanol (97.4 °C), which have similar molar masses
Calculate the bond order for an ion with this configuration: (?2s)2(??2s)2(?2px)2(?2py,?2pz)4(??2py,??2pz)3
Which of the following will increase the percent of HF that is converted to the fluoride ion in water? (a) addition of NaOH (b) addition of HCl (c) addition of NaF