Properties of Acid-base Solution

8/3/2019 Properties of Acid-base Solution

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A solution of acidA solution of acid--basebasepropertiesproperties



y Solution:A homogeneous mixture betweenthe solute and solvent



Electrolyte

Strong

Electrolyte WeakElectrolyte

NaCl Na+ + Cl -

SOLUTION

Non Electrolyte

HCl H+ + Cl -

NaOH Na+ + OH -

CH3COOH mCH3COO- + H+

NH3(aq)mNH4++ OH-

C6H12O6 C6H12O6

C2H5OH C2H5OH

H2OmH++ OH-



Strong

Electrolyte

strongacid

strongbase



Strong acid is an acid which, when put ina lot of water releasing H+ ions.

Strong base is a base which, when put ina lot of water releasing OH-ions



Strong Acids and BasesStrong Acids and Basesy Strong acids arethose that ionized

completely in water.y The dissociation of a

strong base look s lik ethe diagram at theright in that it dissociates into positive and negative

ions.



T he number of ions H+ or OH-ions

can be calculated by using thefollowing formula



Strong Acid

= 1

[H+]

[H+] = a . M



y [ H+] = hydrogen ion concentrationCharacteristics of acid :- Acid can change blue litmus to red

[H+] = a. M

a : the amount of H in the formula acidM : Molarity

Example:H2SO4, HNO3, HI, HCl, HBr, HClO4



Calculate [HCalculate [H++ ] of Strong Acids] of Strong Acids

0.250M H2SO4 is added to water to make afinal volume of 1 liter. What is the H+ of thissolution?

Answer :[H+ ] = a . M = 2 . 0,25 = 0,5



Strong base

= 1

[OH-]

[OH-] = b . M



[OH-] = concentration of hydroxide ionsCharacteristics of base :Base can change red litmus to blue

[OH-] = b. M

b : the amount of OH in the formula baseM : MolarityExample:

bases are formed by group IA and IIAFor example: NaOH, Ba(OH)2



Strong BasesStrong Bases

*LiOH - lithium hydroxide*NaOH - sodium hydroxide

*KOH - potassium hydroxide*RbOH - rubidium hydroxide*CsOH - cesium hydroxide*Ca(OH)2 - calcium hydroxide

*Sr(OH)2 - strontium hydroxide*Ba(OH)2 - barium hydroxide



Calculate pH of strong basesCalculate pH of strong bases

Determine OH- of a 0.750 M KOHsolution.

Answer :

[OH- ] = b . M = 1 . 0,75



ExerciseExercise1. Determine the concentration of H+ ions

a. 100 ml of 0.01 M HNO3 solutionb. 9.8 grams of H2SO4 (Mr. 98) in wateruntil the solution volume 200 ml

2. Determine the concentration of OH-iona. 0.1 M NaOH solutionb. Solution of Ba(OH)2 0.05 Mc. Solution made from 2.8 grams of KOH(Mr=56) in water until the solution volume

100 ml



3. Determine the [H+] a solution of thefollowinga. 50 ml of 0.05 M solution of HBrb. 2 liters of 0.02 M H2SO4 solutionc. Solution made from 3.65 g of HCl

(Mr 36.5) in the water until itsvolume of 2 liters.

d. Mixture of 100 ml of 0.04 M HCland 400 ml of 0.03 M HCle. 100 ml solution of 0.01 mol HI



y Determine the [OH-] some of thefollowing solutionsa. 150 ml of 0.04 M KOH solutionb. 10-4M NaOH solution

c. 23 ml solution of Ba(OH)2 0.001 Md. Solution made from 8 gr NaOH is

dissolved in in water until thesolution volume 8 liters

e.Mixture of 2 liters of 0.6 M KOH and3 liters of Ba(OH)2 0.2 M



WeakElectrolyte

Weak

acid

Weak

base



Weak Acids and Bases

Weak Acids and Bases

y Some acids and bases

ionize only slightly in water.

y These are considered

weak.

y The most important

weak base is

ammonia.



Weak acid is an acid which,when put in a water produces little of H+ ions

Weak base is a base which,when put in a water produces little OH-ions



T o calculate the amount of

H+ or OH-ions by using thefollowing formula



Weak AcidsWeak Acids

y HA(aq) m H+(aq) + A-(aq)

y [H+] = [ A- ]

[HA]

]A][[H ka

-

!

[HA]

][H ka

2

!

[HA].ka][H !



Weak Acid

0<< 1

[H+]

[H+] = .M

[H+] = ¥Ka .M

= [H+]M

= ¥KaM

Ka> the more

powerf ul

properties

of acid

Example :

CH3COOH

H2CO3

H3

PO4

HCN

HCOOH

23



ExampleExample

y Determine [H+] of 0.30 M aceticacid (HC2H3O2) with the Ka of1.8x10-5.

Answer :

[H+] = 2.3x10-3

[HA].ka][H !

[0,3].1,8x10][H 5

!



Weak BasesWeak Bases

y LOH(aq) m L+(aq) + OH-(aq)

y [L+] = [ OH- ]

[LOH]

]OH][[L kb

-

!

[LOH]

][OH kb

2-

!

[LOH].kb][OH !



Weak Base

0<< 1

[OH-]

[OH-] = .M

[OH-] = ¥Kb M

= [OH

-

]M

= ¥KbM

Kb > the more

powerf ul

properties

of base

Example :NH3

AL(OH)3Base areformed

other ofgroup IAand IIA

26



ExampleExample

Determine the OH- of 0.15 Mammonia (NH3) with a Kb=1.8x10-5.

Answer:

[OH-] = 1.6x10-3 M

[LOH].kb][OH !

[0,15].x101,8][OH -5!



ExerciseExercise

1. 600 ml of 0.01 M NH4OH solution has kb= 1.8 x10-5 determine [OH-] and

2. 2,24 liters of NH3

gas dissolved in waterso that the volume of 1 liter if kb = 1.8 x10-5 determine the concentration of OH-

3. 100 ml of 0.1 M solution of LOH has the

same concentration of OH-with 50 ml of0.001 M NaOH solution, determine kb



4. 100 ml of 0.1 M CH3COOHsolution that has ka = 1.8 x 10-5

Determine the [H+] and 5. At a given temperature a 0.1 M

solution of HA decomposes 20%.Determine the [H+] and ka

6. 2.3 g of HCOOH (Mr. 56) wasdissolved in 250 ml of water until

its volume, if ka 1.8 x 10-4.Determine the [H+] and



y Determine the [H+] of H3

PO4solution, 0,1 M if known :

Ka1 = 7.1 x 10-3

ka2 = 6.3 x 10-8

ka3 = 4.3 x 10-13

y Answer :[H+]1 = ¥ (7.1 x10-3) (0.1) = 2.7 x 10-2

[H+] = [H+]1 + [H+]2 + [H+]3

because [H+]2 and [H+]3 is very smallSo [H+] = [H+]1 = 2.7 x 10-2

1,0.10.1,7]H[3

!



1. 0.01 M ,1500 ml HF have ka = 56.8 x10-4,determine the [H +] and

2. 15 g CH3COOH dissolved in water untilthe volume is 5 liters if Ka = 2x10-5

determine the [H+] and the percentage ofionized CH3COOH.

3. HA 0.2 M have ionized 25%, determinethe [H+] and Ka

4.Determine

[H

+

] of 0.1 M H2Aif knownKa1 = 10-7 and ka2 = 10-14

Exercise



5, 100 ml of 0.1 M solution of NH2OH has kb = 10-8,

determine [OH-] and

6 600 ml of NH4OH solution is made by passing0672 liters of NH3 gas at ST P into the water if kb= 2.10-5 determine [OH-] and

7. A weak base LOH 0.1 M in water 2% ionizeddetermine [OH-] and kb

8. 2 liters of 0.003 M KOH solution with [OH-] is thesame with I liter of solution MOH 0,1 M determinethe ionization constant of weak base MOH.

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Properties of Acid-base Solution