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?
A golfer on a fairway is 70 m away from the green, which sits below the level of the fairway by 20 m. If the golfer hits the ball at an angle of 40° with an initial speed of 20 m/s, how close to the green does she come?
A mouse of mass 200 g falls 100 m down a vertical mine shaft and lands at the bottom with a speed of 8.0 m/s. During its fall, how much work is done on the mouse by air resistance
Chemistry is a branch of science that deals with the study of matter,it composition,it structure and the changes it undergoes
Adjei
please, I'm a physics student and I need help in physics
Adjanou
chemistry could also be understood like the sexual attraction/repulsion of the male and female elements. the reaction varies depending on the energy differences of each given gender. + masculine -female.
Pedro
A ball is thrown straight up.it passes a 2.0m high window 7.50 m off the ground on it path up and takes 1.30 s to go past the window.what was the ball initial velocity
2. A sled plus passenger with total mass 50 kg is pulled 20 m across the snow (0.20) at constant velocity by a force directed 25° above the horizontal. Calculate (a) the work of the applied force, (b) the work of friction, and (c) the total work.
you have been hired as an espert witness in a court case involving an automobile accident. the accident involved car A of mass 1500kg which crashed into stationary car B of mass 1100kg. the driver of car A applied his brakes 15 m before he skidded and crashed into car B. after the collision, car A s
can someone explain to me, an ignorant high school student, why the trend of the graph doesn't follow the fact that the higher frequency a sound wave is, the more power it is, hence, making me think the phons output would follow this general trend?
Nevermind i just realied that the graph is the phons output for a person with normal hearing and not just the phons output of the sound waves power, I should read the entire thing next time
Joseph
Follow up question, does anyone know where I can find a graph that accuretly depicts the actual relative "power" output of sound over its frequency instead of just humans hearing
Joseph
"Generation of electrical energy from sound energy | IEEE Conference Publication | IEEE Xplore" ***ieeexplore.ieee.org/document/7150687?reload=true
A string is 3.00 m long with a mass of 5.00 g. The string is held taut with a tension of 500.00 N applied to the string. A pulse is sent down the string. How long does it take the pulse to travel the 3.00 m of the string?
