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] ).
(a) A research-grade pH meter used in a laboratory can have a resolution of 0.001 pH units, an accuracy of ± 0.002 pH units, and may cost in excess of $1000. (b) A portable pH meter has lower resolution (0.01 pH units), lower accuracy (± 0.2 pH units), and a far lower price tag. (credit b: modification of work by Jacopo Werther)
The pH of a solution may also be visually estimated using colored indicators (
[link] ).
(a) A universal indicator assumes a different color in solutions of different pH values. Thus, it can be added to a solution to determine the pH of the solution. The eight vials each contain a universal indicator and 0.1-
M solutions of progressively weaker acids: HCl (pH = l), CH
3 CO
2 H (pH = 3), and NH
4 Cl (pH = 5), deionized water, a neutral substance (pH = 7); and 0.1-
M solutions of the progressively stronger bases: KCl (pH = 7), aniline, C
6 H
5 NH
2 (pH = 9), NH
3 (pH = 11), and NaOH (pH = 13). (b) pH paper contains a mixture of indicators that give different colors in solutions of differing pH values. (credit: modification of work by Sahar Atwa)
Key concepts and summary
The concentration of hydronium ion in a solution of an acid in water is greater than 1.0
10
−7M at 25 °C. The concentration of hydroxide ion in a solution of a base in water is greater than 1.0
10
−7M at 25 °C. The concentration of
in a solution can be expressed as the pH of the solution; pH = −log
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
pOH = −log[OH
− ]
[H
3 O
+ ] = 10
−pH
[OH
− ] = 10
−pOH
pH + pOH = p
Kw = 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
−7M .
Kw 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 hydronium ion concentration in a sample of rainwater is found to be 1.7
10
−6M at 25 °C. What is the concentration of hydroxide ions in the rainwater?
The lymphatic system plays several crucial roles in the human body, functioning as a key component of the immune system and contributing to the maintenance of fluid balance. Its main functions include:
1. Immune Response: The lymphatic system produces and transports lymphocytes, which are a type of
asegid
to transport fluids fats proteins and lymphocytes to the blood stream as lymph
Anatomy is the study of the structure of the body, while physiology is the study of the function of the body. Anatomy looks at the body's organs and systems, while physiology looks at how those organs and systems work together to keep the body functioning.
Enzymes are proteins that help speed up chemical reactions in our bodies. Enzymes are essential for digestion, liver function and much more. Too much or too little of a certain enzyme can cause health problems
Kamara
yes
Prince
how does the stomach protect itself from the damaging effects of HCl
the normal temperature is 37°c or 98.6 °Fahrenheit is important for maintaining the homeostasis in the body
the body regular this temperature through the process called thermoregulation which involves brain skin muscle and other organ working together to maintain stable internal temperature
