Introduction to Acids and Bases

INTRO-ACIDS AND BASES

ACIDS: CONTAINS HYDROGEN (H+) IONS

THEY ARE SOUR, CORROSIVE, CONDUCTORS OF ELECTRICITY (ELECTROLYTE), MAKES BLUE LITMUS
PAPER TURN PINK, PH LESS THAN 7,

STRONG ACIDS: (CSINBC)HYDROCHLORIC ACID (HCL), SULFURIC ACID (H2SO4), HYDRO BROMIC
ACID (HBR), NITRIC ACID (HNO3), COMPLETELY DISSOCIATES IN SOLUTIONS (100%)

WEAK ACIDS: ACETIC ACID (HC2H3O2), CITRIC ACID (C6H8O7), HYDROGEN FLUORIDE (HF)

DOES NOT COMPLETELY DISSOCIATES IN SOLUTIONS ( LESS THAN 5%)

BASES: CONTAINS HYDROXIDE (OH-) IONS

THEY ARE BITTER, CORROSIVE, SLIPPERY, CONDUCTORS OF ELECTRICITY (ELECTROLYTE), MAKES
PINK LITMUS PAPER TURN BLUE, PH GREATER THAN 7,

STRONG BASES: (GROUP1/ GROUP2 WITH OH) NAOH, KOH, CA(OH)2, MG(OH)2

COMPLETELY DISSOCIATES IN SOLUTIONS (100%)

WEAK BASES: AMMONIA (NH3), ACETIC ACID CH3COOH

DOES NOT COMPLETELY DISSOCIATES IN SOLUTIONS ( LESS THAN 5%)

Multiple Choice

What is the dissociation percentage of a strong acid or base?

• 100%

• 75%

• 25%

• 5%

HOW CAN YOU DISTINGUISH BETWEEN THE DEGREES OF

DISSOCIATION FOR WEAK ACIDS AND BASES?

THE DEGREE OF DISSOCIATION OF A WEAK ACID IN WATER IS REPRESENTED BY THE ACID
DISSOCIATION CONSTANT (KA)

THE DEGREE OF DISSOCIATION OF A WEAK BASE IN WATER IS REPRESENTED BY THE BASE
DISSOCIATION CONSTANT (KB).

FOR KA = 4.3X10^-7 OR 1.3X10^-2.(1.3X10^-2IS THE BIGGER NUMBER)

SMALLER NEGATIVE EXPONENT = BIGGER KA OR KB =
GREATER DEGREE OF DISSOCIATION = STRONGER ACID OR BASE = BETTER CONDUCTIVITY)
AND VICE VERSA

Multiple Choice

Which is the weaker acid or base

$$A.\ 4.8x10^{-8}\ or\ B.\ 5.8x10^{-11}$$

• A

• B

Multiple Choice

Which is the Strongest Base?

• Ammonia

• Dimethylamine

• Hydrazine

• Hydroxylamine

Multiple Choice

Which is the weakest electrolyte?

• Nitrous Acid

• Sulfurous Acid

• Urea

• Pyridine

PH DECREASES AS CONCENTRATION[H+] INCREASES

AND CONDUCTIVITY INCREASES

The pH Scale and pH
Values of Some Common
Substances

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WRITE TO LEARN

PH ( POWER OF HYDROGEN OR POTENTIAL OF HYDROGEN)

PH OF A SOLUTION IS DEFINED AS: THE NEGATIVE LOGARITHM OF
HYDROGEN [H+] OR HYDRONIUM ION [H3O+] CONCENTRATION

WRITTEN AS:

PH = –LOG[H+]

PH RANGE :PH = 7; NEUTRAL

PH > 7; BASIC

HIGHER THE PH, MORE BASIC.

PH < 7; ACIDIC

LOWER THE PH, MORE ACIDIC.

Multiple Choice

Is it an Acid or base or both?

$$Mg\left(OH\right)_2$$

• Acid

• Base

• Both

Multiple Choice

Is it an Acid or base or both?

Electrolytes

• Acid

• Base

• Both

Multiple Choice

Is it an Acid or base or both?

$$H_2SO_4$$

• Acid

• Base

• Both

Multiple Choice

Is it an Acid or base or both?

pH above 7

• Acid

• Base

• Both

Multiple Choice

Is it an Acid or base or both?

More $$OH^-$$ Ions

• Acid

• Base

• Both

Multiple Choice

Is it an Acid or base or both?

pH less than 7

• Acid

• Base

• Both

Multiple Choice

Is it an Acid or base or both?

More $$H^+$$ Ions

• Acid

• Base

• Both

Multiple Choice

Which is the strongest acid?

• Distilled water

• Vinegar

• Battery Acid

• Lye

• Solution X

ESSENTIAL QUESTION

HOW IS THE HYDROGEN ION CONCENTRATION
USED TO CALCULATE THE PH OF A SOLUTION?

EXAMPLE 1.

CONSIDER AN AQUEOUS SOLUTION WITH A HYDROGEN ION (H+) CONCENTRATION OF 1.0 × 10−2M.

THE PH IS CALCULATED USING THE: NEGATIVE OF THE LOG OF THE HYDROGEN ION CONCENTRATION.

PH = −LOG (1.0 × 10−2) = 5

KEY IN YOUR CALCULATOR

(-)

LOG

1.0 X10 ^ (-) 2

ENTER

CALCULATE THE PH FOR EACH OF THE FOLLOWING

SOLUTIONS GIVEN THEIR HYDROGEN ION

CONCENTRATIONS TO BE:

1. 6.3 × 10−4M

ANSWER: PH = −LOG 6.3 × 10−4=

2. 1.0 × 10-4M

ANSWER: PH = -LOG 1.0 × 10-4=

3. 0.040 M =

ANSWER: PH=-LOG 0.040 M =

3.2

4.00

1.3979

Multiple Choice

Calculate the pH

$$6.3x10^{-4}$$

• 3.2

• 4.8

• 6.4

• 14

Multiple Choice

Calculate the pH

$$1.0x10^{-4}$$

• 10

• 4

• 8

• 3

Multiple Choice

Calculate the pH

0.040

• 2.8

• 1.4

• 3.5

• 6.8

HOW IS THE HYDROXIDE ION CONCENTRATION [OH−]
CONCENTRATION USED TO CALCULATE THE PH OF A

SOLUTION?
STEP 1

GIVEN THE [OH]-CALCULATE POH:

POH = −LOG [OH−]

THEN:

PH + POH = 14

THEREFORE:

PH = 14-POH

POH = 14 – PH

Multiple Choice

Calculate the pH of a solution that has a hydroxide ion(OH-) concentration of $$1.3x10^{-10}$$

• 9.9

• 4.3

• 5.8

• 14