11

The Chemistry of The Chemistry of Acids and BasesAcids and BasesThe Chemistry of The Chemistry of Acids and BasesAcids and Bases

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Acid and Base ScaleAcids pH from 0 to 7Neutral pH is 7 Base pH from 7 to 14

pH is a measure of hydrogen ion concentrationpH = -log[H+]

33AcidsHave a sour taste.

Vinegar, orange juice, lemonade.

Donates an H+

Have a bitter taste.

Feel slippery.

Donates OH-

Ammonia, detergents, bleach

Bases

44

Monoprotic vs. Diprotic

Monoprotic- an acid that can donate only 1 proton to a base (HCl)

Diprotic- an acid that has two ionizable hydrogen atoms in each molecule, such as sulfuric acid (H2SO4)

Effects titrations

55ACID-BASE REACTIONSACID-BASE REACTIONS

TitrationsTitrationsACID-BASE REACTIONSACID-BASE REACTIONS

TitrationsTitrations

What is a titration? What is a titration?

HH22CC22OO4(q)4(q) + 2NaOH + 2NaOH(aq)(aq) Na Na22CC22OO4(aq)4(aq) + 2H + 2H22OO(l)(l)

acidacid basebase Ionic SaltIonic Salt WaterWater

Oxalic acid,

H2C2O4

A common laboratory method of chemistry that is used to determine the unknown concentration of an identified acid or base

66

HCl(aq) + NaOH(aq) HOH(l) +NaCl(aq)

•When we add the two together what do we get?

–Neutralization Reaction

•What is the equivalence point?

–Equal moles of acid and base

Acid + Base

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Titration1. 1. Add known solution to Add known solution to

unknown solution to unknown solution to determine concentration.determine concentration.

2. Phenolphthalein indicator 2. Phenolphthalein indicator shows the equivalence shows the equivalence point. (Acid = Base)point. (Acid = Base)

This is called This is called NEUTRALIZATION.NEUTRALIZATION.

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35.62 mL of NaOH is neutralized with 25.2 mL of 35.62 mL of NaOH is neutralized with 25.2 mL of

0.0998 M HCl by titration to an equivalence point. 0.0998 M HCl by titration to an equivalence point.

What is the concentration of the NaOH?What is the concentration of the NaOH?

Ma Va = Mb Vb

Ma Va = Mb Vb

(0.0998 M) (25.2 mL) = 0.0706 M

(35.62 mL)

Standardization of a solution of NaOH Standardization of a solution of NaOH Standardization of a solution of NaOH Standardization of a solution of NaOH

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Practice

a. 35.0b. 1.12c. 25.8d. 62.4e. 39.3

In a titration of 35.00 mL of 0.737 M H2SO4,

__________ mL of a 0.827 M KOH solution is required for neutralization.

In a titration of 35.00 mL of 0.737 M H2SO4,

__________ mL of a 0.827 M KOH solution is required for neutralization.

1010

RemindersHomework:

•Titrations WS

•Read through lab

Reminders:•Parent Letter DUE – bring in ASAP

•Extra Credit Due Friday (5/11)

•Thermo Test Corrections Due Thursday (5/10) at 8:30 am

•Sig Figs Redemption Thursday (5/10) at 7:30 am

1111

Wednesday and ThursdayMay 9 and 10

1212

Review Homework

1313

Review Homework

1414

What is too pink?

1515

The Stopcock

ClosedOpen

1616The Meniscus

• Read “upside down”

• Use paper to help see line

1717

More Hints• Label beakers (tape on

hood)

• Use paper to see color change

1818

Acid or Base and Skin

Severity will vary with concentration, but

BE SAFE, NOT SORRY!!

Rinse skin IMMEDIATELY and call for Ms. Bjorge

1919

Standardization of a Base Lab

Wear goggles and aprons

If I have to tell you once to put them on you are out with a ZERO!

Leave Buret in holder

You will have to do multiple trials (as many as 10)

Lab “write up” due BEGINNING of the period on Friday

2020Done in lab?

Did you complete at least 3 GOOD trials?

The more the merrier!

Homework:

Lab Write Up

Study for quiz

Reminders:Parent Letter DUE – bring in ASAP

Extra Credit Due Friday (5/11)

Thermo Test Corrections Due Thursday (5/10) at 8:30 am

Sig Figs Redemption Thursday (5/10) at 7:30 am

Acid/Base Quiz Friday (5/11)