Ch. 15

Titration

And pH

Ionization of Water

• _____________________: two water molecules produce a hydronium ion and a hydroxide ion by transfer of a proton.

15-2

Ionization of Water

In a neutral solution, ________________________.

Ionization constant of water = Kw

Kw =H3O+ OH- = 1.0 x 10-14M

If the H3O+ = 1.0 x 10-5M, the solution is _________.___________________________, so the hydronium

concentration is greater than it would be in a neutral solution.

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ExampleExample: A 1.0 x 10-4M solution of HNO3 has been prepared for a

lab. Calculate the H3O+ and OH- of this solution._________________________________

H3O+ = 1.0 x 10-4M

_________________________

OH- = 1.0 x 10-14M = 1.0 x 10-14M

H3O+ 1.0 x 10-4M

= 1.0 x 10-10M

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Practice1) Determine the H3O+ and OH- of a solution that is 1.0 x 10-4M

Ca(OH)2.

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The pH Scale• _____: the negative of the common logarithm of the hydronium ion

concentration.

________________

= - log (1.0 x 10-7M) = 7.0

___________________________

= - log (1.0 x 10-7M) = 7.0

pH + pOH = 14.0

______________________________________________

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The pH Scale

ExampleExample: What is the pH of a solution if the H3O+ is 3.4 x 10-5M?

pH = -log H3O+ = - log (3.4 x 10-5M)

On your calculator, ______________________

Keep in mind, it is the negative of the log, so change the sign on your answer:

pH = _________

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Practice2) What is the pH of a solution if the H3O+ is

2.5 x 10-2M?

-

15-9

pH to H3O+pH = -log H3O+log H3O+ = -pH____________________

Example: What is the H3O+, OH- if the pH is 7.52? Is the solution acidic or basic?

H3O+ = 10-pH = 10-7.52 ____________________________. = 3.0 x 10-8

OH- = 1.0 x 10-14M = 1.0 x 10-14M = _______________

H3O+ 3.0 x 10-8M

pH is greater than 7.0, the solution is __________.15-10

pH to H3O+3) What is the H3O+, OH- if the pH is 12.0? Is

the solution acidic or basic?

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Indicators• ___________________: compounds whose colors are

sensitive to pH.

• _________________: the pH range over which an indicator ___________.

• ____________: determines the pH of a solution by measuring the voltage between two electrodes that are placed in the solution.

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Indicators

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Titration• _____________: the controlled addition and

measurement of the amount of a solution of___________ ________________ required to react completely with a measured amount of a solution of unknown concentration.

• ___________________: the point at which the two solutions used in a titration are present in chemically equivalent amounts.

• ____________: the point in a titration at which an indicator changes color.

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Titration

15-15

Titration

15-16

Titration• __________________: the solution that contains

the precisely known concentration of a solute.

• __________________: a highly purified solid compound used to check the concentration of the known solution in a titiration.

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Buffers

• Buffered Solution: resists changes in pH with the addition of an acid or a base.

Ch. 15

The

End!15-19